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• How to Write a Literature Review | Guide, Examples, & Templates

How to Write a Literature Review | Guide, Examples, & Templates

Published on January 2, 2023 by Shona McCombes . Revised on September 11, 2023.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research that you can later apply to your paper, thesis, or dissertation topic .

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates, and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarize sources—it analyzes, synthesizes , and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

What is the purpose of a literature review, examples of literature reviews, step 1 – search for relevant literature, step 2 – evaluate and select sources, step 3 – identify themes, debates, and gaps, step 4 – outline your literature review’s structure, step 5 – write your literature review, free lecture slides, other interesting articles, frequently asked questions, introduction.

• Quick Run-through
• Step 1 & 2

When you write a thesis , dissertation , or research paper , you will likely have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and its scholarly context
• Develop a theoretical framework and methodology for your research
• Position your work in relation to other researchers and theorists
• Show how your research addresses a gap or contributes to a debate
• Evaluate the current state of research and demonstrate your knowledge of the scholarly debates around your topic.

Writing literature reviews is a particularly important skill if you want to apply for graduate school or pursue a career in research. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research problem and questions .

Make a list of keywords

Start by creating a list of keywords related to your research question. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list as you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some useful databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can also use boolean operators to help narrow down your search.

Make sure to read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

You likely won’t be able to read absolutely everything that has been written on your topic, so it will be necessary to evaluate which sources are most relevant to your research question.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models, and methods?
• Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible , and make sure you read any landmark studies and major theories in your field of research.

You can use our template to summarize and evaluate sources you’re thinking about using. Click on either button below to download.

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It is important to keep track of your sources with citations to avoid plagiarism . It can be helpful to make an annotated bibliography , where you compile full citation information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

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To begin organizing your literature review’s argument and structure, be sure you understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly visual platforms like Instagram and Snapchat—this is a gap that you could address in your own research.

There are various approaches to organizing the body of a literature review. Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarizing sources in order.

Try to analyze patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organize your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text , your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, you can follow these tips:

• Summarize and synthesize: give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: don’t just paraphrase other researchers — add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically evaluate: mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: use transition words and topic sentences to draw connections, comparisons and contrasts

In the conclusion, you should summarize the key findings you have taken from the literature and emphasize their significance.

When you’ve finished writing and revising your literature review, don’t forget to proofread thoroughly before submitting. Not a language expert? Check out Scribbr’s professional proofreading services !

This article has been adapted into lecture slides that you can use to teach your students about writing a literature review.

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If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

• Sampling methods
• Simple random sampling
• Stratified sampling
• Cluster sampling
• Likert scales
• Reproducibility

 Statistics

• Null hypothesis
• Statistical power
• Probability distribution
• Effect size
• Poisson distribution

Research bias

• Optimism bias
• Cognitive bias
• Implicit bias
• Hawthorne effect
• Anchoring bias
• Explicit bias

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarize yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your thesis or dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

A literature review is a survey of credible sources on a topic, often used in dissertations , theses, and research papers . Literature reviews give an overview of knowledge on a subject, helping you identify relevant theories and methods, as well as gaps in existing research. Literature reviews are set up similarly to other  academic texts , with an introduction , a main body, and a conclusion .

An  annotated bibliography is a list of  source references that has a short description (called an annotation ) for each of the sources. It is often assigned as part of the research process for a  paper .  

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• University of Texas Libraries

Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
• Choose databases and search
• Review Results
• Synthesize Results
• Analyze Results
• Librarian Support

What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
• Last Updated: Oct 26, 2022 2:49 PM
• URL: https://guides.lib.utexas.edu/literaturereviews

• UConn Library
• Literature Review: The What, Why and How-to Guide
• Introduction

Literature Review: The What, Why and How-to Guide — Introduction

• Getting Started
• How to Pick a Topic
• Strategies to Find Sources
• Evaluating Sources & Lit. Reviews
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings

What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D.  The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review?  A literature could be written to accomplish different aims:

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews .  Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

• A research paper assigned in a course
• A thesis or dissertation
• A grant proposal
• An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

• Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework:  10.1177/08948453211037398  

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

• Example : The effect of leave policies on increasing fertility: a systematic review:  10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

• Example : Employment Instability and Fertility in Europe: A Meta-Analysis:  10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts .  Journal of Advanced Nursing , 53 (3), 311-318.

• Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis:  10.1177/05390184221113735

Literature Reviews in the Health Sciences

• UConn Health subject guide on systematic reviews Explanation of the different review types used in health sciences literature as well as tools to help you find the right review type
• << Previous: Getting Started
• Next: How to Pick a Topic >>
• Last Updated: Sep 21, 2022 2:16 PM
• URL: https://guides.lib.uconn.edu/literaturereview

Literature Reviews

What this handout is about.

This handout will explain what literature reviews are and offer insights into the form and construction of literature reviews in the humanities, social sciences, and sciences.

Introduction

OK. You’ve got to write a literature review. You dust off a novel and a book of poetry, settle down in your chair, and get ready to issue a “thumbs up” or “thumbs down” as you leaf through the pages. “Literature review” done. Right?

Wrong! The “literature” of a literature review refers to any collection of materials on a topic, not necessarily the great literary texts of the world. “Literature” could be anything from a set of government pamphlets on British colonial methods in Africa to scholarly articles on the treatment of a torn ACL. And a review does not necessarily mean that your reader wants you to give your personal opinion on whether or not you liked these sources.

What is a literature review, then?

A literature review discusses published information in a particular subject area, and sometimes information in a particular subject area within a certain time period.

A literature review can be just a simple summary of the sources, but it usually has an organizational pattern and combines both summary and synthesis. A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information. It might give a new interpretation of old material or combine new with old interpretations. Or it might trace the intellectual progression of the field, including major debates. And depending on the situation, the literature review may evaluate the sources and advise the reader on the most pertinent or relevant.

But how is a literature review different from an academic research paper?

The main focus of an academic research paper is to develop a new argument, and a research paper is likely to contain a literature review as one of its parts. In a research paper, you use the literature as a foundation and as support for a new insight that you contribute. The focus of a literature review, however, is to summarize and synthesize the arguments and ideas of others without adding new contributions.

Why do we write literature reviews?

Literature reviews provide you with a handy guide to a particular topic. If you have limited time to conduct research, literature reviews can give you an overview or act as a stepping stone. For professionals, they are useful reports that keep them up to date with what is current in the field. For scholars, the depth and breadth of the literature review emphasizes the credibility of the writer in his or her field. Literature reviews also provide a solid background for a research paper’s investigation. Comprehensive knowledge of the literature of the field is essential to most research papers.

Who writes these things, anyway?

Literature reviews are written occasionally in the humanities, but mostly in the sciences and social sciences; in experiment and lab reports, they constitute a section of the paper. Sometimes a literature review is written as a paper in itself.

Let’s get to it! What should I do before writing the literature review?

If your assignment is not very specific, seek clarification from your instructor:

• Roughly how many sources should you include?
• What types of sources (books, journal articles, websites)?
• Should you summarize, synthesize, or critique your sources by discussing a common theme or issue?
• Should you evaluate your sources?
• Should you provide subheadings and other background information, such as definitions and/or a history?

Find models

Look for other literature reviews in your area of interest or in the discipline and read them to get a sense of the types of themes you might want to look for in your own research or ways to organize your final review. You can simply put the word “review” in your search engine along with your other topic terms to find articles of this type on the Internet or in an electronic database. The bibliography or reference section of sources you’ve already read are also excellent entry points into your own research.

Narrow your topic

There are hundreds or even thousands of articles and books on most areas of study. The narrower your topic, the easier it will be to limit the number of sources you need to read in order to get a good survey of the material. Your instructor will probably not expect you to read everything that’s out there on the topic, but you’ll make your job easier if you first limit your scope.

Keep in mind that UNC Libraries have research guides and to databases relevant to many fields of study. You can reach out to the subject librarian for a consultation: https://library.unc.edu/support/consultations/ .

And don’t forget to tap into your professor’s (or other professors’) knowledge in the field. Ask your professor questions such as: “If you had to read only one book from the 90’s on topic X, what would it be?” Questions such as this help you to find and determine quickly the most seminal pieces in the field.

Consider whether your sources are current

Some disciplines require that you use information that is as current as possible. In the sciences, for instance, treatments for medical problems are constantly changing according to the latest studies. Information even two years old could be obsolete. However, if you are writing a review in the humanities, history, or social sciences, a survey of the history of the literature may be what is needed, because what is important is how perspectives have changed through the years or within a certain time period. Try sorting through some other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to consider what is currently of interest to scholars in this field and what is not.

Strategies for writing the literature review

Find a focus.

A literature review, like a term paper, is usually organized around ideas, not the sources themselves as an annotated bibliography would be organized. This means that you will not just simply list your sources and go into detail about each one of them, one at a time. No. As you read widely but selectively in your topic area, consider instead what themes or issues connect your sources together. Do they present one or different solutions? Is there an aspect of the field that is missing? How well do they present the material and do they portray it according to an appropriate theory? Do they reveal a trend in the field? A raging debate? Pick one of these themes to focus the organization of your review.

Convey it to your reader

A literature review may not have a traditional thesis statement (one that makes an argument), but you do need to tell readers what to expect. Try writing a simple statement that lets the reader know what is your main organizing principle. Here are a couple of examples:

The current trend in treatment for congestive heart failure combines surgery and medicine. More and more cultural studies scholars are accepting popular media as a subject worthy of academic consideration.

Consider organization

You’ve got a focus, and you’ve stated it clearly and directly. Now what is the most effective way of presenting the information? What are the most important topics, subtopics, etc., that your review needs to include? And in what order should you present them? Develop an organization for your review at both a global and local level:

First, cover the basic categories

Just like most academic papers, literature reviews also must contain at least three basic elements: an introduction or background information section; the body of the review containing the discussion of sources; and, finally, a conclusion and/or recommendations section to end the paper. The following provides a brief description of the content of each:

• Introduction: Gives a quick idea of the topic of the literature review, such as the central theme or organizational pattern.
• Body: Contains your discussion of sources and is organized either chronologically, thematically, or methodologically (see below for more information on each).
• Conclusions/Recommendations: Discuss what you have drawn from reviewing literature so far. Where might the discussion proceed?

Organizing the body

Once you have the basic categories in place, then you must consider how you will present the sources themselves within the body of your paper. Create an organizational method to focus this section even further.

To help you come up with an overall organizational framework for your review, consider the following scenario:

You’ve decided to focus your literature review on materials dealing with sperm whales. This is because you’ve just finished reading Moby Dick, and you wonder if that whale’s portrayal is really real. You start with some articles about the physiology of sperm whales in biology journals written in the 1980’s. But these articles refer to some British biological studies performed on whales in the early 18th century. So you check those out. Then you look up a book written in 1968 with information on how sperm whales have been portrayed in other forms of art, such as in Alaskan poetry, in French painting, or on whale bone, as the whale hunters in the late 19th century used to do. This makes you wonder about American whaling methods during the time portrayed in Moby Dick, so you find some academic articles published in the last five years on how accurately Herman Melville portrayed the whaling scene in his novel.

Now consider some typical ways of organizing the sources into a review:

• Chronological: If your review follows the chronological method, you could write about the materials above according to when they were published. For instance, first you would talk about the British biological studies of the 18th century, then about Moby Dick, published in 1851, then the book on sperm whales in other art (1968), and finally the biology articles (1980s) and the recent articles on American whaling of the 19th century. But there is relatively no continuity among subjects here. And notice that even though the sources on sperm whales in other art and on American whaling are written recently, they are about other subjects/objects that were created much earlier. Thus, the review loses its chronological focus.
• By publication: Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on biological studies of sperm whales if the progression revealed a change in dissection practices of the researchers who wrote and/or conducted the studies.
• By trend: A better way to organize the above sources chronologically is to examine the sources under another trend, such as the history of whaling. Then your review would have subsections according to eras within this period. For instance, the review might examine whaling from pre-1600-1699, 1700-1799, and 1800-1899. Under this method, you would combine the recent studies on American whaling in the 19th century with Moby Dick itself in the 1800-1899 category, even though the authors wrote a century apart.
• Thematic: Thematic reviews of literature are organized around a topic or issue, rather than the progression of time. However, progression of time may still be an important factor in a thematic review. For instance, the sperm whale review could focus on the development of the harpoon for whale hunting. While the study focuses on one topic, harpoon technology, it will still be organized chronologically. The only difference here between a “chronological” and a “thematic” approach is what is emphasized the most: the development of the harpoon or the harpoon technology.But more authentic thematic reviews tend to break away from chronological order. For instance, a thematic review of material on sperm whales might examine how they are portrayed as “evil” in cultural documents. The subsections might include how they are personified, how their proportions are exaggerated, and their behaviors misunderstood. A review organized in this manner would shift between time periods within each section according to the point made.
• Methodological: A methodological approach differs from the two above in that the focusing factor usually does not have to do with the content of the material. Instead, it focuses on the “methods” of the researcher or writer. For the sperm whale project, one methodological approach would be to look at cultural differences between the portrayal of whales in American, British, and French art work. Or the review might focus on the economic impact of whaling on a community. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed. Once you’ve decided on the organizational method for the body of the review, the sections you need to include in the paper should be easy to figure out. They should arise out of your organizational strategy. In other words, a chronological review would have subsections for each vital time period. A thematic review would have subtopics based upon factors that relate to the theme or issue.

Sometimes, though, you might need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. Put in only what is necessary. Here are a few other sections you might want to consider:

• Current Situation: Information necessary to understand the topic or focus of the literature review.
• History: The chronological progression of the field, the literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Methods and/or Standards: The criteria you used to select the sources in your literature review or the way in which you present your information. For instance, you might explain that your review includes only peer-reviewed articles and journals.

Questions for Further Research: What questions about the field has the review sparked? How will you further your research as a result of the review?

Begin composing

Once you’ve settled on a general pattern of organization, you’re ready to write each section. There are a few guidelines you should follow during the writing stage as well. Here is a sample paragraph from a literature review about sexism and language to illuminate the following discussion:

However, other studies have shown that even gender-neutral antecedents are more likely to produce masculine images than feminine ones (Gastil, 1990). Hamilton (1988) asked students to complete sentences that required them to fill in pronouns that agreed with gender-neutral antecedents such as “writer,” “pedestrian,” and “persons.” The students were asked to describe any image they had when writing the sentence. Hamilton found that people imagined 3.3 men to each woman in the masculine “generic” condition and 1.5 men per woman in the unbiased condition. Thus, while ambient sexism accounted for some of the masculine bias, sexist language amplified the effect. (Source: Erika Falk and Jordan Mills, “Why Sexist Language Affects Persuasion: The Role of Homophily, Intended Audience, and Offense,” Women and Language19:2).

Use evidence

In the example above, the writers refer to several other sources when making their point. A literature review in this sense is just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence to show that what you are saying is valid.

Be selective

Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the review’s focus, whether it is thematic, methodological, or chronological.

Use quotes sparingly

Falk and Mills do not use any direct quotes. That is because the survey nature of the literature review does not allow for in-depth discussion or detailed quotes from the text. Some short quotes here and there are okay, though, if you want to emphasize a point, or if what the author said just cannot be rewritten in your own words. Notice that Falk and Mills do quote certain terms that were coined by the author, not common knowledge, or taken directly from the study. But if you find yourself wanting to put in more quotes, check with your instructor.

Summarize and synthesize

Remember to summarize and synthesize your sources within each paragraph as well as throughout the review. The authors here recapitulate important features of Hamilton’s study, but then synthesize it by rephrasing the study’s significance and relating it to their own work.

Keep your own voice

While the literature review presents others’ ideas, your voice (the writer’s) should remain front and center. Notice that Falk and Mills weave references to other sources into their own text, but they still maintain their own voice by starting and ending the paragraph with their own ideas and their own words. The sources support what Falk and Mills are saying.

Use caution when paraphrasing

When paraphrasing a source that is not your own, be sure to represent the author’s information or opinions accurately and in your own words. In the preceding example, Falk and Mills either directly refer in the text to the author of their source, such as Hamilton, or they provide ample notation in the text when the ideas they are mentioning are not their own, for example, Gastil’s. For more information, please see our handout on plagiarism .

Revise, revise, revise

Draft in hand? Now you’re ready to revise. Spending a lot of time revising is a wise idea, because your main objective is to present the material, not the argument. So check over your review again to make sure it follows the assignment and/or your outline. Then, just as you would for most other academic forms of writing, rewrite or rework the language of your review so that you’ve presented your information in the most concise manner possible. Be sure to use terminology familiar to your audience; get rid of unnecessary jargon or slang. Finally, double check that you’ve documented your sources and formatted the review appropriately for your discipline. For tips on the revising and editing process, see our handout on revising drafts .

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

Anson, Chris M., and Robert A. Schwegler. 2010. The Longman Handbook for Writers and Readers , 6th ed. New York: Longman.

Jones, Robert, Patrick Bizzaro, and Cynthia Selfe. 1997. The Harcourt Brace Guide to Writing in the Disciplines . New York: Harcourt Brace.

Lamb, Sandra E. 1998. How to Write It: A Complete Guide to Everything You’ll Ever Write . Berkeley: Ten Speed Press.

Rosen, Leonard J., and Laurence Behrens. 2003. The Allyn & Bacon Handbook , 5th ed. New York: Longman.

Troyka, Lynn Quittman, and Doug Hesse. 2016. Simon and Schuster Handbook for Writers , 11th ed. London: Pearson.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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Research Methods

• Getting Started
• Literature Review Research
• Research Design
• Research Design By Discipline
• SAGE Research Methods
• Teaching with SAGE Research Methods

Literature Review

• What is a Literature Review?
• What is NOT a Literature Review?
• Purposes of a Literature Review
• Types of Literature Reviews
• Literature Reviews vs. Systematic Reviews
• Systematic vs. Meta-Analysis

Literature Review  is a comprehensive survey of the works published in a particular field of study or line of research, usually over a specific period of time, in the form of an in-depth, critical bibliographic essay or annotated list in which attention is drawn to the most significant works.

Also, we can define a literature review as the collected body of scholarly works related to a topic:

• Summarizes and analyzes previous research relevant to a topic
• Includes scholarly books and articles published in academic journals
• Can be an specific scholarly paper or a section in a research paper

The objective of a Literature Review is to find previous published scholarly works relevant to an specific topic

• Help gather ideas or information
• Keep up to date in current trends and findings
• Help develop new questions

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Helps focus your own research questions or problems
• Discovers relationships between research studies/ideas.
• Suggests unexplored ideas or populations
• Identifies major themes, concepts, and researchers on a topic.
• Tests assumptions; may help counter preconceived ideas and remove unconscious bias.
• Identifies critical gaps, points of disagreement, or potentially flawed methodology or theoretical approaches.
• Indicates potential directions for future research.

All content in this section is from Literature Review Research from Old Dominion University 

Keep in mind the following, a literature review is NOT:

Not an essay 

Not an annotated bibliography  in which you summarize each article that you have reviewed.  A literature review goes beyond basic summarizing to focus on the critical analysis of the reviewed works and their relationship to your research question.

Not a research paper   where you select resources to support one side of an issue versus another.  A lit review should explain and consider all sides of an argument in order to avoid bias, and areas of agreement and disagreement should be highlighted.

A literature review serves several purposes. For example, it

• provides thorough knowledge of previous studies; introduces seminal works.
• helps focus one’s own research topic.
• identifies a conceptual framework for one’s own research questions or problems; indicates potential directions for future research.
• suggests previously unused or underused methodologies, designs, quantitative and qualitative strategies.
• identifies gaps in previous studies; identifies flawed methodologies and/or theoretical approaches; avoids replication of mistakes.
• helps the researcher avoid repetition of earlier research.
• suggests unexplored populations.
• determines whether past studies agree or disagree; identifies controversy in the literature.
• tests assumptions; may help counter preconceived ideas and remove unconscious bias.

As Kennedy (2007) notes*, it is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the original studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally that become part of the lore of field. In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews.

Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are several approaches to how they can be done, depending upon the type of analysis underpinning your study. Listed below are definitions of types of literature reviews:

Argumentative Review      This form examines literature selectively in order to support or refute an argument, deeply imbedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to to make summary claims of the sort found in systematic reviews.

Integrative Review      Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication.

Historical Review      Few things rest in isolation from historical precedent. Historical reviews are focused on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review      A review does not always focus on what someone said [content], but how they said it [method of analysis]. This approach provides a framework of understanding at different levels (i.e. those of theory, substantive fields, research approaches and data collection and analysis techniques), enables researchers to draw on a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection and data analysis, and helps highlight many ethical issues which we should be aware of and consider as we go through our study.

Systematic Review      This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyse data from the studies that are included in the review. Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?"

Theoretical Review      The purpose of this form is to concretely examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review help establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

* Kennedy, Mary M. "Defining a Literature."  Educational Researcher  36 (April 2007): 139-147.

All content in this section is from The Literature Review created by Dr. Robert Larabee USC

Robinson, P. and Lowe, J. (2015),  Literature reviews vs systematic reviews.  Australian and New Zealand Journal of Public Health, 39: 103-103. doi: 10.1111/1753-6405.12393

What's in the name? The difference between a Systematic Review and a Literature Review, and why it matters . By Lynn Kysh from University of Southern California

Systematic review or meta-analysis?

A  systematic review  answers a defined research question by collecting and summarizing all empirical evidence that fits pre-specified eligibility criteria.

A  meta-analysis  is the use of statistical methods to summarize the results of these studies.

Systematic reviews, just like other research articles, can be of varying quality. They are a significant piece of work (the Centre for Reviews and Dissemination at York estimates that a team will take 9-24 months), and to be useful to other researchers and practitioners they should have:

• clearly stated objectives with pre-defined eligibility criteria for studies
• explicit, reproducible methodology
• a systematic search that attempts to identify all studies
• assessment of the validity of the findings of the included studies (e.g. risk of bias)
• systematic presentation, and synthesis, of the characteristics and findings of the included studies

Not all systematic reviews contain meta-analysis. 

Meta-analysis is the use of statistical methods to summarize the results of independent studies. By combining information from all relevant studies, meta-analysis can provide more precise estimates of the effects of health care than those derived from the individual studies included within a review.  More information on meta-analyses can be found in  Cochrane Handbook, Chapter 9 .

A meta-analysis goes beyond critique and integration and conducts secondary statistical analysis on the outcomes of similar studies.  It is a systematic review that uses quantitative methods to synthesize and summarize the results.

An advantage of a meta-analysis is the ability to be completely objective in evaluating research findings.  Not all topics, however, have sufficient research evidence to allow a meta-analysis to be conducted.  In that case, an integrative review is an appropriate strategy. 

Some of the content in this section is from Systematic reviews and meta-analyses: step by step guide created by Kate McAllister.

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• Next: Research Design >>
• Last Updated: Aug 21, 2023 4:07 PM
• URL: https://guides.lib.udel.edu/researchmethods

What is the Background in a Research Paper?

An effective Background section in your manuscript establishes the context for your study. And while original research requires novel findings, providing the necessary background information for these findings may be just as important. It lets your readers know that your findings are novel, important, and worthy of their time and attention.

Updated on October 3, 2022

A good Background section explains the history and nature of your research question in relation to existing literature – a “state of the art.” This section, along with the rationale, helps readers understand why you chose to study this problem and why your study is worthwhile. This article will show you how to do this.

Read on to better understand the:

• Real purpose of the Background section
• Typical length of a Background section and its placement
• Elements of an effective Background

What is the Background section of a research paper?

The Background section is an essential element of every study, answering:

• What do we already know about the topic?
• How does your study relate to what's been done so far in your field?
• What is its scope?
• Why does the topic warrant your interest and their interest?
• How did you develop the research question that you'll later introduce?

In grant writing, a Background section is often referred to as the “state of the art,” and this is a useful term to have in mind when writing this part of your paper.

What comes next?

After you make the above points,

• Formulate your research question/hypothesis . Research aims and objectives should be closely related to how you'll fill the gap you've identified in the literature. Your research gap is the central theme of your article and why people should read it.
• Summarize how you'll address it in the paper . Your methodology needs to be appropriate for addressing the “problem” you've identified.
• Describe the significance of your study . Show how your research fits into the bigger picture.

Note that the Background section isn't the same as the research rationale. Rather, it provides the relevant information the reader needs so they can follow your rationale. For example, it

• Explains scientific terms
• Provides available data and statistics on the topic
• Describes the methods used so far on your topic. Especially if these are different from what you're going to do. Take special care here, because this is often where peer reviewers focus intently.

This is a logical approach to what comes after the study's background. Use it and the reader can easily follow along from the broader information to the specific details that come later. Crucially, they'll have confidence that your analysis and findings are valid.

Where should the background be placed in a research paper?

Usually, the background comes after the statement of the problem, in the Introduction section. Logically, you need to provide the study context before discussing the research questions, methodology, and results.

The background can be found in:

The abstract

The background typically forms the first few sentences of the abstract. Why did you do the study? Most journals state this clearly. In an unstructured (no subheadings) abstract, it's the first sentence or two. In a structured abstract, it might be called the Introduction, Background, or State-of-the-Art.

PLOS Medicine , for example, asks for research article abstracts to be split into three sections: Background, Methods and Findings, and Conclusions. Journals in the humanities or social sciences might not clearly ask for it because articles sometimes have a looser structure than STEM articles.

The first part of the Introduction section

In the journal Nature , for example, the Introduction should be around 200 words and include

• Two to three sentences giving a basic introduction to the field.
• The background and rationale of the study are stated briefly.
• A simple phrase “Here we show ...”, or “In this study, we show ....” (to round out the Introduction).

The Journal of Organic Chemistry has similar author guidelines.

The Background as a distinct section

This is often the case for research proposals or some types of reports, as discussed above. Rather than reviewing the literature, this is a concise summary of what's currently known in the field relevant to the question being addressed in this proposed study.

How long should the Background section be?

As mentioned, there's no set length for the Background section. It generally depends on the journal and the content of your manuscript. Check the journal's author guidelines, the research center, granting agency, etc. If it's still not clear or if the instructions are contradictory, email or phone them directly.

The length of your background will depend on:

The manuscript length and content

A book-length study needs a more extensive Background than a four-page research article. Exploring a relatively unknown method or question might also need a longer Background.

For example, see this Frontiers article on the applications of artificial intelligence for developing COVID-19 vaccines. It has a seven-paragraph long Background (1,200 words) in a separate section. The authors need to discuss earlier successful uses of machine learning for therapy discovery to make a convincing case.

An academic paper published in an international journal is usually around 5,000 words. Your paper needs to be balanced, with appropriate text lengths used for the different sections: It would make no sense to have a 300-word introduction and then 4,000 words for the methods, for example. In a 5,000-word manuscript, you'll be able to use about 1,500 for the introduction, which includes the background.

How much you need to show your understanding of the topic

A lengthy grant application might need a longer Background (sub-)section. That's because if they're going to grant you money, they need a very good reason to. You'll need to show that the work is both interesting and doable. The Background is where you can do this.

What should the Background of a research manuscript include?

The Background of a research paper needs to show two things:

The study's territory ( scope )

First, provide a general overview of the field. Scientists in most disciplines should find it relatively easy to understand. Be broad, keep it interesting. Don't go into the specifics of your particular study.

Let's look at two examples:

• one from basic research (seeking to generate new knowledge)
• one from applied research (trying to solve or improve existing processes or products)

Applied research

This Frontiers in Artificial Intelligence article explores how AI can help discover treatments for COVID-19.

The background of the study can be found (i) in the abstract and (ii) in a separate section discussed at the end of this article. The abstract starts with this general overview: “SARS-COV-2 has roused the scientific community with a call to action to combat the growing pandemic.” ( Arshadi et al., 2020 ). This is broad, and it's interesting. This is a topic that many researchers (even from outside this specific area) may want to learn more about.

Think of any theories, models, concepts, or terms (maybe borrowed from different disciplines) that may be unfamiliar to your reader. Be sure to clarify them in plainer language, if necessary.

For example, this systematic review looks at the connections of physician burnout with career engagement and quality of patient care. The Background is in the Introduction section. It starts by defining what burnout is:

• “Burnout is defined as a syndrome related to work that involves three key dimensions.” ( Hodkinson et al., 2022 )

The authors go on to explain its three aspects: emotional exhaustion, depersonalization, and a sense of reduced personal accomplishment.

Basic research

Imagine you're investigating how universities' moves to online teaching during the COVID-19 pandemic impacted students' learning outcomes in the United Kingdom. The overview could be:

• The COVID-19 pandemic and the ensuing lockdown generated tremendous challenges across the higher education sector. University campuses were forced to close. Face-to-face teaching and assessment transitioned into a virtual format.

2. The niche in the field (motivation)

To establish the niche in your field, describe what drove you to explore this specific topic.

• Explain how (un)successfully previous studies have investigated the problem.
• Note the knowledge gap or present a problem with a currently used process/practice/product.

After setting the stage, the abstract of the Frontiers in Artificial Intelligence article identifies a problem:

• “At the time of this writing, there are as yet no novel antiviral agents or approved vaccines available for deployment as a frontline defense.” ( Arshadi et al., 2020 )

The authors need to support their claim that computational methods can help discover new COVID-19 treatments. They do so by referring to previous research findings:

• “In the last decade, machine learning-based models, trained on specific biomolecules, have offered inexpensive and rapid implementation methods for the discovery of effective viral therapies.” ( Arshadi et al., 2020 )

Going back to the study on students' learning outcomes after universities introduced e-learning. The background section will next identify and describe the current knowledge gap and your proposed method of fixing it. It may be something like:

• Existing literature and studies by the UK Department for Education reveal x + y changes and effects on teaching and learning. Yet they provide little to no information on students' learning outcomes. Understanding the impact of online teaching and assessments on student outcomes is key to adopting future teaching practices and ensuring students from disadvantaged backgrounds are not left behind.

How is the background different from the literature review?

Both the background and literature review sections compile previous studies that are relevant and important to the topic.

Despite their similarities, they're different in scope and aims.

Overall, the research background could be seen as a small part of the detailed critical discussion in the literature review. Almost always, primary research articles do not include a detailed literature review.

How is the Background different from the Introduction section?

Although often part of the Introduction, the Background differs from the Introduction in scope and aim.

Breakdown of the Background in published articles

Consider this systematic review looking at the connections of physician burnout with career engagement and quality of patient care.

The Background is placed in the Introduction section. It's critical, consistent, and logically structured, moving from general to specific information.

You can also check out the summary paragraph breakdown provided by Nature. (Nature's “summary paragraph” is essentially an abstract.)

And if you're looking for some help, or have an article that's finished but needs a pre-submission review click here to connect with one of our expert AJE editors.

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• Knowledge Base
• Dissertation
• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list if you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can use boolean operators to help narrow down your search:

Read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models and methods? Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible, and make sure you read any landmark studies and major theories in your field of research.

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

You can use our free APA Reference Generator for quick, correct, consistent citations.

To begin organising your literature review’s argument and structure, you need to understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly-visual platforms like Instagram and Snapchat – this is a gap that you could address in your own research.

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarising sources in order.

Try to analyse patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organise your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text, your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, discussing the significance of findings in relation to the literature as a whole.
• Critically evaluate: mention the strengths and weaknesses of your sources.
• Write in well-structured paragraphs: use transitions and topic sentences to draw connections, comparisons and contrasts.

In the conclusion, you should summarise the key findings you have taken from the literature and emphasise their significance.

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

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Background information identifies and describes the history and nature of a well-defined research problem with reference to contextualizing existing literature. The background information should indicate the root of the problem being studied, appropriate context of the problem in relation to theory, research, and/or practice , its scope, and the extent to which previous studies have successfully investigated the problem, noting, in particular, where gaps exist that your study attempts to address. Background information does not replace the literature review section of a research paper; it is intended to place the research problem within a specific context and an established plan for its solution.

Fitterling, Lori. Researching and Writing an Effective Background Section of a Research Paper. Kansas City University of Medicine & Biosciences; Creating a Research Paper: How to Write the Background to a Study. DurousseauElectricalInstitute.com; Background Information: Definition of Background Information. Literary Devices Definition and Examples of Literary Terms.

Importance of Having Enough Background Information

Background information expands upon the key points stated in the beginning of your introduction but is not intended to be the main focus of the paper. It generally supports the question, what is the most important information the reader needs to understand before continuing to read the paper? Sufficient background information helps the reader determine if you have a basic understanding of the research problem being investigated and promotes confidence in the overall quality of your analysis and findings. This information provides the reader with the essential context needed to conceptualize the research problem and its significance before moving on to a more thorough analysis of prior research.

Forms of contextualization included in background information can include describing one or more of the following:

• Cultural -- placed within the learned behavior of a specific group or groups of people.
• Economic -- of or relating to systems of production and management of material wealth and/or business activities.
• Gender -- located within the behavioral, cultural, or psychological traits typically associated with being self-identified as male, female, or other form of  gender expression.
• Historical -- the time in which something takes place or was created and how the condition of time influences how you interpret it.
• Interdisciplinary -- explanation of theories, concepts, ideas, or methodologies borrowed from other disciplines applied to the research problem rooted in a discipline other than the discipline where your paper resides.
• Philosophical -- clarification of the essential nature of being or of phenomena as it relates to the research problem.
• Physical/Spatial -- reflects the meaning of space around something and how that influences how it is understood.
• Political -- concerns the environment in which something is produced indicating it's public purpose or agenda.
• Social -- the environment of people that surrounds something's creation or intended audience, reflecting how the people associated with something use and interpret it.
• Temporal -- reflects issues or events of, relating to, or limited by time. Concerns past, present, or future contextualization and not just a historical past.

Background information can also include summaries of important research studies . This can be a particularly important element of providing background information if an innovative or groundbreaking study about the research problem laid a foundation for further research or there was a key study that is essential to understanding your arguments. The priority is to summarize for the reader what is known about the research problem before you conduct the analysis of prior research. This is accomplished with a general summary of the foundational research literature [with citations] that document findings that inform your study's overall aims and objectives.

NOTE : Research studies cited as part of the background information of your introduction should not include very specific, lengthy explanations. This should be discussed in greater detail in your literature review section. If you find a study requiring lengthy explanation, consider moving it to the literature review section.

ANOTHER NOTE : In some cases, your paper's introduction only needs to introduce the research problem, explain its significance, and then describe a road map for how you are going to address the problem; the background information basically forms the introduction part of your literature review. That said, while providing background information is not required, including it in the introduction is a way to highlight important contextual information that could otherwise be hidden or overlooked by the reader if placed in the literature review section.

Background of the Problem Section: What do you Need to Consider? Anonymous. Harvard University; Hopkins, Will G. How to Write a Research Paper. SPORTSCIENCE, Perspectives/Research Resources. Department of Physiology and School of Physical Education, University of Otago, 1999; Green, L. H. How to Write the Background/Introduction Section. Physics 499 Powerpoint slides. University of Illinois; Pyrczak, Fred. Writing Empirical Research Reports: A Basic Guide for Students of the Social and Behavioral Sciences . 8th edition. Glendale, CA: Pyrczak Publishing, 2014; Stevens, Kathleen C. “Can We Improve Reading by Teaching Background Information?.” Journal of Reading 25 (January 1982): 326-329; Woodall, W. Gill. Writing the Background and Significance Section. Senior Research Scientist and Professor of Communication. Center on Alcoholism, Substance Abuse, and Addictions. University of New Mexico.

Structure and Writing Style

Providing background information in the introduction of a research paper serves as a bridge that links the reader to the research problem . Precisely how long and in-depth this bridge should be is largely dependent upon how much information you think the reader will need to know in order to fully understand the problem being discussed and to appreciate why the issues you are investigating are important.

From another perspective, the length and detail of background information also depends on the degree to which you need to demonstrate to your professor how much you understand the research problem. Keep this in mind because providing pertinent background information can be an effective way to demonstrate that you have a clear grasp of key issues, debates, and concepts related to your overall study.

The structure and writing style of your background information can vary depending upon the complexity of your research and/or the nature of the assignment. However, in most cases it should be limited to only one to two paragraphs in your introduction.

Given this, here are some questions to consider while writing this part of your introduction :

• Are there concepts, terms, theories, or ideas that may be unfamiliar to the reader and, thus, require additional explanation?
• Are there historical elements that need to be explored in order to provide needed context, to highlight specific people, issues, or events, or to lay a foundation for understanding the emergence of a current issue or event?
• Are there theories, concepts, or ideas borrowed from other disciplines or academic traditions that may be unfamiliar to the reader and therefore require further explanation?
• Is there a key study or small set of studies that set the stage for understanding the topic and frames why it is important to conduct further research on the topic?
• Y our study uses a method of analysis never applied before;
• Your study investigates a very esoteric or complex research problem;
• Your study introduces new or unique variables that need to be taken into account ; or,
• Your study relies upon analyzing unique texts or documents, such as, archival materials or primary documents like diaries or personal letters that do not represent the established body of source literature on the topic?

Almost all introductions to a research problem require some contextualizing, but the scope and breadth of background information varies depending on your assumption about the reader's level of prior knowledge . However, despite this assessment, background information should be brief and succinct and sets the stage for the elaboration of critical points or in-depth discussion of key issues in the literature review section of your paper.

Writing Tip

Background Information vs. the Literature Review

Incorporating background information into the introduction is intended to provide the reader with critical information about the topic being studied, such as, highlighting and expanding upon foundational studies conducted in the past, describing important historical events that inform why and in what ways the research problem exists, defining key components of your study [concepts, people, places, phenomena] and/or placing the research problem within a particular context. Although introductory background information can often blend into the literature review portion of the paper, essential background information should not be considered a substitute for a comprehensive review and synthesis of relevant research literature.

Hart, Cris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage, 1998; Pyrczak, Fred. Writing Empirical Research Reports: A Basic Guide for Students of the Social and Behavioral Sciences . 8th edition. Glendale, CA: Pyrczak Publishing, 2014.

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Writing Research Background

Research background is a brief outline of the most important studies that have been conducted so far presented in a chronological order. Research background part in introduction chapter can be also headed ‘Background of the Study.” Research background should also include a brief discussion of major theories and models related to the research problem.

Specifically, when writing research background you can discuss major theories and models related to your research problem in a chronological order to outline historical developments in the research area.  When writing research background, you also need to demonstrate how your research relates to what has been done so far in the research area.

Research background is written after the literature review. Therefore, literature review has to be the first and the longest stage in the research process, even before the formulation of research aims and objectives, right after the selection of the research area. Once the research area is selected, the literature review is commenced in order to identify gaps in the research area.

Research aims and objectives need to be closely associated with the elimination of this gap in the literature. The main difference between background of the study and literature review is that the former only provides general information about what has been done so far in the research area, whereas the latter elaborates and critically reviews previous works.

John Dudovskiy

Writing the parts of scientific reports

19 Writing the literature review or background chapter

The more advanced you are in your studies, the more important it will be to make the connection between your own research and the research of others. Therefore, when you begin a project or have identified a research question, you usually go and search for relevant work done by others.

The literature review consists of two parts (Ridely, 2012): the finished product which is part of a thesis and the process which is searching and critically reading the work done by others, which is often called literature search or in this book literature – based research .  So, the purpose of what is called literature review is initially often to read around the subject, to explore the field and gain a thorough understanding of current work and perspectives. However, this reviewing of literature is an ongoing activity and lasts until the day you complete the final draft because understanding and comparing with existing literature can help you to analyse and interpret your results.

Purpose of the literature review

The purposes of a literature review can be summarized as follows:

• To provide a historical background for your research.
• To explore the current context in which your research is situated by referring to debates, issues or questions in the field, which helps to show the significance of a problem for research.
• To identify a discussion of relevant theories and concepts, which you then will probably draw on.
• To gain an overview of relevant methodology or methods used to collect and analyse data in a particular field.
• To clarify and introduce relevant terminology to be used in your research.
• To identify relevant research and to show how your work extends or challenges it.
• To establish a gap in the work in the field.
• To provide supporting evidence for a problem or claim.

When is a specific literature review chapter required?

Even though no research can be done without knowledge of and referring to relevant research of others, your (primary) purposes and whether you will write a dedicated chapter with the title Literature review depends on the kind of research project and the conventions within your discipline. There is for example a significant difference between applied and theoretical research, where more extensive and critical literature reviews are expected. There are further significant differences between research done at the beginning of your university studies or for a BA, BSc, MA, MSc or PhD thesis. For a Master or PhD thesis a high level of awareness of the research done in your field and deep and broad discussion of it is expected.

However, the insights from your literature review will strongly influence the content of other chapters, such as the Background (if you include such a section in your study) or the Methodology section . As already mentioned, you very often refer to theory (i.e. literature) when analysing and interpreting data in the Discussion section .

Overall structure

If you include a separate chapter with the title literature review, you can follow the principle below. As always organize your writing along a general-to-specific pattern:

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• v.21(3); Fall 2022

Literature Reviews, Theoretical Frameworks, and Conceptual Frameworks: An Introduction for New Biology Education Researchers

Julie a. luft.

† Department of Mathematics, Social Studies, and Science Education, Mary Frances Early College of Education, University of Georgia, Athens, GA 30602-7124

Sophia Jeong

‡ Department of Teaching & Learning, College of Education & Human Ecology, Ohio State University, Columbus, OH 43210

Robert Idsardi

§ Department of Biology, Eastern Washington University, Cheney, WA 99004

Grant Gardner

∥ Department of Biology, Middle Tennessee State University, Murfreesboro, TN 37132

Associated Data

To frame their work, biology education researchers need to consider the role of literature reviews, theoretical frameworks, and conceptual frameworks as critical elements of the research and writing process. However, these elements can be confusing for scholars new to education research. This Research Methods article is designed to provide an overview of each of these elements and delineate the purpose of each in the educational research process. We describe what biology education researchers should consider as they conduct literature reviews, identify theoretical frameworks, and construct conceptual frameworks. Clarifying these different components of educational research studies can be helpful to new biology education researchers and the biology education research community at large in situating their work in the broader scholarly literature.

INTRODUCTION

Discipline-based education research (DBER) involves the purposeful and situated study of teaching and learning in specific disciplinary areas ( Singer et al. , 2012 ). Studies in DBER are guided by research questions that reflect disciplines’ priorities and worldviews. Researchers can use quantitative data, qualitative data, or both to answer these research questions through a variety of methodological traditions. Across all methodologies, there are different methods associated with planning and conducting educational research studies that include the use of surveys, interviews, observations, artifacts, or instruments. Ensuring the coherence of these elements to the discipline’s perspective also involves situating the work in the broader scholarly literature. The tools for doing this include literature reviews, theoretical frameworks, and conceptual frameworks. However, the purpose and function of each of these elements is often confusing to new education researchers. The goal of this article is to introduce new biology education researchers to these three important elements important in DBER scholarship and the broader educational literature.

The first element we discuss is a review of research (literature reviews), which highlights the need for a specific research question, study problem, or topic of investigation. Literature reviews situate the relevance of the study within a topic and a field. The process may seem familiar to science researchers entering DBER fields, but new researchers may still struggle in conducting the review. Booth et al. (2016b) highlight some of the challenges novice education researchers face when conducting a review of literature. They point out that novice researchers struggle in deciding how to focus the review, determining the scope of articles needed in the review, and knowing how to be critical of the articles in the review. Overcoming these challenges (and others) can help novice researchers construct a sound literature review that can inform the design of the study and help ensure the work makes a contribution to the field.

The second and third highlighted elements are theoretical and conceptual frameworks. These guide biology education research (BER) studies, and may be less familiar to science researchers. These elements are important in shaping the construction of new knowledge. Theoretical frameworks offer a way to explain and interpret the studied phenomenon, while conceptual frameworks clarify assumptions about the studied phenomenon. Despite the importance of these constructs in educational research, biology educational researchers have noted the limited use of theoretical or conceptual frameworks in published work ( DeHaan, 2011 ; Dirks, 2011 ; Lo et al. , 2019 ). In reviewing articles published in CBE—Life Sciences Education ( LSE ) between 2015 and 2019, we found that fewer than 25% of the research articles had a theoretical or conceptual framework (see the Supplemental Information), and at times there was an inconsistent use of theoretical and conceptual frameworks. Clearly, these frameworks are challenging for published biology education researchers, which suggests the importance of providing some initial guidance to new biology education researchers.

Fortunately, educational researchers have increased their explicit use of these frameworks over time, and this is influencing educational research in science, technology, engineering, and mathematics (STEM) fields. For instance, a quick search for theoretical or conceptual frameworks in the abstracts of articles in Educational Research Complete (a common database for educational research) in STEM fields demonstrates a dramatic change over the last 20 years: from only 778 articles published between 2000 and 2010 to 5703 articles published between 2010 and 2020, a more than sevenfold increase. Greater recognition of the importance of these frameworks is contributing to DBER authors being more explicit about such frameworks in their studies.

Collectively, literature reviews, theoretical frameworks, and conceptual frameworks work to guide methodological decisions and the elucidation of important findings. Each offers a different perspective on the problem of study and is an essential element in all forms of educational research. As new researchers seek to learn about these elements, they will find different resources, a variety of perspectives, and many suggestions about the construction and use of these elements. The wide range of available information can overwhelm the new researcher who just wants to learn the distinction between these elements or how to craft them adequately.

Our goal in writing this paper is not to offer specific advice about how to write these sections in scholarly work. Instead, we wanted to introduce these elements to those who are new to BER and who are interested in better distinguishing one from the other. In this paper, we share the purpose of each element in BER scholarship, along with important points on its construction. We also provide references for additional resources that may be beneficial to better understanding each element. Table 1 summarizes the key distinctions among these elements.

Comparison of literature reviews, theoretical frameworks, and conceptual reviews

This article is written for the new biology education researcher who is just learning about these different elements or for scientists looking to become more involved in BER. It is a result of our own work as science education and biology education researchers, whether as graduate students and postdoctoral scholars or newly hired and established faculty members. This is the article we wish had been available as we started to learn about these elements or discussed them with new educational researchers in biology.

LITERATURE REVIEWS

Purpose of a literature review.

A literature review is foundational to any research study in education or science. In education, a well-conceptualized and well-executed review provides a summary of the research that has already been done on a specific topic and identifies questions that remain to be answered, thus illustrating the current research project’s potential contribution to the field and the reasoning behind the methodological approach selected for the study ( Maxwell, 2012 ). BER is an evolving disciplinary area that is redefining areas of conceptual emphasis as well as orientations toward teaching and learning (e.g., Labov et al. , 2010 ; American Association for the Advancement of Science, 2011 ; Nehm, 2019 ). As a result, building comprehensive, critical, purposeful, and concise literature reviews can be a challenge for new biology education researchers.

Building Literature Reviews

There are different ways to approach and construct a literature review. Booth et al. (2016a) provide an overview that includes, for example, scoping reviews, which are focused only on notable studies and use a basic method of analysis, and integrative reviews, which are the result of exhaustive literature searches across different genres. Underlying each of these different review processes are attention to the s earch process, a ppraisa l of articles, s ynthesis of the literature, and a nalysis: SALSA ( Booth et al. , 2016a ). This useful acronym can help the researcher focus on the process while building a specific type of review.

However, new educational researchers often have questions about literature reviews that are foundational to SALSA or other approaches. Common questions concern determining which literature pertains to the topic of study or the role of the literature review in the design of the study. This section addresses such questions broadly while providing general guidance for writing a narrative literature review that evaluates the most pertinent studies.

The literature review process should begin before the research is conducted. As Boote and Beile (2005 , p. 3) suggested, researchers should be “scholars before researchers.” They point out that having a good working knowledge of the proposed topic helps illuminate avenues of study. Some subject areas have a deep body of work to read and reflect upon, providing a strong foundation for developing the research question(s). For instance, the teaching and learning of evolution is an area of long-standing interest in the BER community, generating many studies (e.g., Perry et al. , 2008 ; Barnes and Brownell, 2016 ) and reviews of research (e.g., Sickel and Friedrichsen, 2013 ; Ziadie and Andrews, 2018 ). Emerging areas of BER include the affective domain, issues of transfer, and metacognition ( Singer et al. , 2012 ). Many studies in these areas are transdisciplinary and not always specific to biology education (e.g., Rodrigo-Peiris et al. , 2018 ; Kolpikova et al. , 2019 ). These newer areas may require reading outside BER; fortunately, summaries of some of these topics can be found in the Current Insights section of the LSE website.

In focusing on a specific problem within a broader research strand, a new researcher will likely need to examine research outside BER. Depending upon the area of study, the expanded reading list might involve a mix of BER, DBER, and educational research studies. Determining the scope of the reading is not always straightforward. A simple way to focus one’s reading is to create a “summary phrase” or “research nugget,” which is a very brief descriptive statement about the study. It should focus on the essence of the study, for example, “first-year nonmajor students’ understanding of evolution,” “metacognitive prompts to enhance learning during biochemistry,” or “instructors’ inquiry-based instructional practices after professional development programming.” This type of phrase should help a new researcher identify two or more areas to review that pertain to the study. Focusing on recent research in the last 5 years is a good first step. Additional studies can be identified by reading relevant works referenced in those articles. It is also important to read seminal studies that are more than 5 years old. Reading a range of studies should give the researcher the necessary command of the subject in order to suggest a research question.

Given that the research question(s) arise from the literature review, the review should also substantiate the selected methodological approach. The review and research question(s) guide the researcher in determining how to collect and analyze data. Often the methodological approach used in a study is selected to contribute knowledge that expands upon what has been published previously about the topic (see Institute of Education Sciences and National Science Foundation, 2013 ). An emerging topic of study may need an exploratory approach that allows for a description of the phenomenon and development of a potential theory. This could, but not necessarily, require a methodological approach that uses interviews, observations, surveys, or other instruments. An extensively studied topic may call for the additional understanding of specific factors or variables; this type of study would be well suited to a verification or a causal research design. These could entail a methodological approach that uses valid and reliable instruments, observations, or interviews to determine an effect in the studied event. In either of these examples, the researcher(s) may use a qualitative, quantitative, or mixed methods methodological approach.

Even with a good research question, there is still more reading to be done. The complexity and focus of the research question dictates the depth and breadth of the literature to be examined. Questions that connect multiple topics can require broad literature reviews. For instance, a study that explores the impact of a biology faculty learning community on the inquiry instruction of faculty could have the following review areas: learning communities among biology faculty, inquiry instruction among biology faculty, and inquiry instruction among biology faculty as a result of professional learning. Biology education researchers need to consider whether their literature review requires studies from different disciplines within or outside DBER. For the example given, it would be fruitful to look at research focused on learning communities with faculty in STEM fields or in general education fields that result in instructional change. It is important not to be too narrow or too broad when reading. When the conclusions of articles start to sound similar or no new insights are gained, the researcher likely has a good foundation for a literature review. This level of reading should allow the researcher to demonstrate a mastery in understanding the researched topic, explain the suitability of the proposed research approach, and point to the need for the refined research question(s).

The literature review should include the researcher’s evaluation and critique of the selected studies. A researcher may have a large collection of studies, but not all of the studies will follow standards important in the reporting of empirical work in the social sciences. The American Educational Research Association ( Duran et al. , 2006 ), for example, offers a general discussion about standards for such work: an adequate review of research informing the study, the existence of sound and appropriate data collection and analysis methods, and appropriate conclusions that do not overstep or underexplore the analyzed data. The Institute of Education Sciences and National Science Foundation (2013) also offer Common Guidelines for Education Research and Development that can be used to evaluate collected studies.

Because not all journals adhere to such standards, it is important that a researcher review each study to determine the quality of published research, per the guidelines suggested earlier. In some instances, the research may be fatally flawed. Examples of such flaws include data that do not pertain to the question, a lack of discussion about the data collection, poorly constructed instruments, or an inadequate analysis. These types of errors result in studies that are incomplete, error-laden, or inaccurate and should be excluded from the review. Most studies have limitations, and the author(s) often make them explicit. For instance, there may be an instructor effect, recognized bias in the analysis, or issues with the sample population. Limitations are usually addressed by the research team in some way to ensure a sound and acceptable research process. Occasionally, the limitations associated with the study can be significant and not addressed adequately, which leaves a consequential decision in the hands of the researcher. Providing critiques of studies in the literature review process gives the reader confidence that the researcher has carefully examined relevant work in preparation for the study and, ultimately, the manuscript.

A solid literature review clearly anchors the proposed study in the field and connects the research question(s), the methodological approach, and the discussion. Reviewing extant research leads to research questions that will contribute to what is known in the field. By summarizing what is known, the literature review points to what needs to be known, which in turn guides decisions about methodology. Finally, notable findings of the new study are discussed in reference to those described in the literature review.

Within published BER studies, literature reviews can be placed in different locations in an article. When included in the introductory section of the study, the first few paragraphs of the manuscript set the stage, with the literature review following the opening paragraphs. Cooper et al. (2019) illustrate this approach in their study of course-based undergraduate research experiences (CUREs). An introduction discussing the potential of CURES is followed by an analysis of the existing literature relevant to the design of CUREs that allows for novel student discoveries. Within this review, the authors point out contradictory findings among research on novel student discoveries. This clarifies the need for their study, which is described and highlighted through specific research aims.

A literature reviews can also make up a separate section in a paper. For example, the introduction to Todd et al. (2019) illustrates the need for their research topic by highlighting the potential of learning progressions (LPs) and suggesting that LPs may help mitigate learning loss in genetics. At the end of the introduction, the authors state their specific research questions. The review of literature following this opening section comprises two subsections. One focuses on learning loss in general and examines a variety of studies and meta-analyses from the disciplines of medical education, mathematics, and reading. The second section focuses specifically on LPs in genetics and highlights student learning in the midst of LPs. These separate reviews provide insights into the stated research question.

Suggestions and Advice

A well-conceptualized, comprehensive, and critical literature review reveals the understanding of the topic that the researcher brings to the study. Literature reviews should not be so big that there is no clear area of focus; nor should they be so narrow that no real research question arises. The task for a researcher is to craft an efficient literature review that offers a critical analysis of published work, articulates the need for the study, guides the methodological approach to the topic of study, and provides an adequate foundation for the discussion of the findings.

In our own writing of literature reviews, there are often many drafts. An early draft may seem well suited to the study because the need for and approach to the study are well described. However, as the results of the study are analyzed and findings begin to emerge, the existing literature review may be inadequate and need revision. The need for an expanded discussion about the research area can result in the inclusion of new studies that support the explanation of a potential finding. The literature review may also prove to be too broad. Refocusing on a specific area allows for more contemplation of a finding.

It should be noted that there are different types of literature reviews, and many books and articles have been written about the different ways to embark on these types of reviews. Among these different resources, the following may be helpful in considering how to refine the review process for scholarly journals:

• Booth, A., Sutton, A., & Papaioannou, D. (2016a). Systemic approaches to a successful literature review (2nd ed.). Los Angeles, CA: Sage. This book addresses different types of literature reviews and offers important suggestions pertaining to defining the scope of the literature review and assessing extant studies.
• Booth, W. C., Colomb, G. G., Williams, J. M., Bizup, J., & Fitzgerald, W. T. (2016b). The craft of research (4th ed.). Chicago: University of Chicago Press. This book can help the novice consider how to make the case for an area of study. While this book is not specifically about literature reviews, it offers suggestions about making the case for your study.
• Galvan, J. L., & Galvan, M. C. (2017). Writing literature reviews: A guide for students of the social and behavioral sciences (7th ed.). Routledge. This book offers guidance on writing different types of literature reviews. For the novice researcher, there are useful suggestions for creating coherent literature reviews.

THEORETICAL FRAMEWORKS

Purpose of theoretical frameworks.

As new education researchers may be less familiar with theoretical frameworks than with literature reviews, this discussion begins with an analogy. Envision a biologist, chemist, and physicist examining together the dramatic effect of a fog tsunami over the ocean. A biologist gazing at this phenomenon may be concerned with the effect of fog on various species. A chemist may be interested in the chemical composition of the fog as water vapor condenses around bits of salt. A physicist may be focused on the refraction of light to make fog appear to be “sitting” above the ocean. While observing the same “objective event,” the scientists are operating under different theoretical frameworks that provide a particular perspective or “lens” for the interpretation of the phenomenon. Each of these scientists brings specialized knowledge, experiences, and values to this phenomenon, and these influence the interpretation of the phenomenon. The scientists’ theoretical frameworks influence how they design and carry out their studies and interpret their data.

Within an educational study, a theoretical framework helps to explain a phenomenon through a particular lens and challenges and extends existing knowledge within the limitations of that lens. Theoretical frameworks are explicitly stated by an educational researcher in the paper’s framework, theory, or relevant literature section. The framework shapes the types of questions asked, guides the method by which data are collected and analyzed, and informs the discussion of the results of the study. It also reveals the researcher’s subjectivities, for example, values, social experience, and viewpoint ( Allen, 2017 ). It is essential that a novice researcher learn to explicitly state a theoretical framework, because all research questions are being asked from the researcher’s implicit or explicit assumptions of a phenomenon of interest ( Schwandt, 2000 ).

Selecting Theoretical Frameworks

Theoretical frameworks are one of the most contemplated elements in our work in educational research. In this section, we share three important considerations for new scholars selecting a theoretical framework.

The first step in identifying a theoretical framework involves reflecting on the phenomenon within the study and the assumptions aligned with the phenomenon. The phenomenon involves the studied event. There are many possibilities, for example, student learning, instructional approach, or group organization. A researcher holds assumptions about how the phenomenon will be effected, influenced, changed, or portrayed. It is ultimately the researcher’s assumption(s) about the phenomenon that aligns with a theoretical framework. An example can help illustrate how a researcher’s reflection on the phenomenon and acknowledgment of assumptions can result in the identification of a theoretical framework.

In our example, a biology education researcher may be interested in exploring how students’ learning of difficult biological concepts can be supported by the interactions of group members. The phenomenon of interest is the interactions among the peers, and the researcher assumes that more knowledgeable students are important in supporting the learning of the group. As a result, the researcher may draw on Vygotsky’s (1978) sociocultural theory of learning and development that is focused on the phenomenon of student learning in a social setting. This theory posits the critical nature of interactions among students and between students and teachers in the process of building knowledge. A researcher drawing upon this framework holds the assumption that learning is a dynamic social process involving questions and explanations among students in the classroom and that more knowledgeable peers play an important part in the process of building conceptual knowledge.

It is important to state at this point that there are many different theoretical frameworks. Some frameworks focus on learning and knowing, while other theoretical frameworks focus on equity, empowerment, or discourse. Some frameworks are well articulated, and others are still being refined. For a new researcher, it can be challenging to find a theoretical framework. Two of the best ways to look for theoretical frameworks is through published works that highlight different frameworks.

When a theoretical framework is selected, it should clearly connect to all parts of the study. The framework should augment the study by adding a perspective that provides greater insights into the phenomenon. It should clearly align with the studies described in the literature review. For instance, a framework focused on learning would correspond to research that reported different learning outcomes for similar studies. The methods for data collection and analysis should also correspond to the framework. For instance, a study about instructional interventions could use a theoretical framework concerned with learning and could collect data about the effect of the intervention on what is learned. When the data are analyzed, the theoretical framework should provide added meaning to the findings, and the findings should align with the theoretical framework.

A study by Jensen and Lawson (2011) provides an example of how a theoretical framework connects different parts of the study. They compared undergraduate biology students in heterogeneous and homogeneous groups over the course of a semester. Jensen and Lawson (2011) assumed that learning involved collaboration and more knowledgeable peers, which made Vygotsky’s (1978) theory a good fit for their study. They predicted that students in heterogeneous groups would experience greater improvement in their reasoning abilities and science achievements with much of the learning guided by the more knowledgeable peers.

In the enactment of the study, they collected data about the instruction in traditional and inquiry-oriented classes, while the students worked in homogeneous or heterogeneous groups. To determine the effect of working in groups, the authors also measured students’ reasoning abilities and achievement. Each data-collection and analysis decision connected to understanding the influence of collaborative work.

Their findings highlighted aspects of Vygotsky’s (1978) theory of learning. One finding, for instance, posited that inquiry instruction, as a whole, resulted in reasoning and achievement gains. This links to Vygotsky (1978) , because inquiry instruction involves interactions among group members. A more nuanced finding was that group composition had a conditional effect. Heterogeneous groups performed better with more traditional and didactic instruction, regardless of the reasoning ability of the group members. Homogeneous groups worked better during interaction-rich activities for students with low reasoning ability. The authors attributed the variation to the different types of helping behaviors of students. High-performing students provided the answers, while students with low reasoning ability had to work collectively through the material. In terms of Vygotsky (1978) , this finding provided new insights into the learning context in which productive interactions can occur for students.

Another consideration in the selection and use of a theoretical framework pertains to its orientation to the study. This can result in the theoretical framework prioritizing individuals, institutions, and/or policies ( Anfara and Mertz, 2014 ). Frameworks that connect to individuals, for instance, could contribute to understanding their actions, learning, or knowledge. Institutional frameworks, on the other hand, offer insights into how institutions, organizations, or groups can influence individuals or materials. Policy theories provide ways to understand how national or local policies can dictate an emphasis on outcomes or instructional design. These different types of frameworks highlight different aspects in an educational setting, which influences the design of the study and the collection of data. In addition, these different frameworks offer a way to make sense of the data. Aligning the data collection and analysis with the framework ensures that a study is coherent and can contribute to the field.

New understandings emerge when different theoretical frameworks are used. For instance, Ebert-May et al. (2015) prioritized the individual level within conceptual change theory (see Posner et al. , 1982 ). In this theory, an individual’s knowledge changes when it no longer fits the phenomenon. Ebert-May et al. (2015) designed a professional development program challenging biology postdoctoral scholars’ existing conceptions of teaching. The authors reported that the biology postdoctoral scholars’ teaching practices became more student-centered as they were challenged to explain their instructional decision making. According to the theory, the biology postdoctoral scholars’ dissatisfaction in their descriptions of teaching and learning initiated change in their knowledge and instruction. These results reveal how conceptual change theory can explain the learning of participants and guide the design of professional development programming.

The communities of practice (CoP) theoretical framework ( Lave, 1988 ; Wenger, 1998 ) prioritizes the institutional level , suggesting that learning occurs when individuals learn from and contribute to the communities in which they reside. Grounded in the assumption of community learning, the literature on CoP suggests that, as individuals interact regularly with the other members of their group, they learn about the rules, roles, and goals of the community ( Allee, 2000 ). A study conducted by Gehrke and Kezar (2017) used the CoP framework to understand organizational change by examining the involvement of individual faculty engaged in a cross-institutional CoP focused on changing the instructional practice of faculty at each institution. In the CoP, faculty members were involved in enhancing instructional materials within their department, which aligned with an overarching goal of instituting instruction that embraced active learning. Not surprisingly, Gehrke and Kezar (2017) revealed that faculty who perceived the community culture as important in their work cultivated institutional change. Furthermore, they found that institutional change was sustained when key leaders served as mentors and provided support for faculty, and as faculty themselves developed into leaders. This study reveals the complexity of individual roles in a COP in order to support institutional instructional change.

It is important to explicitly state the theoretical framework used in a study, but elucidating a theoretical framework can be challenging for a new educational researcher. The literature review can help to identify an applicable theoretical framework. Focal areas of the review or central terms often connect to assumptions and assertions associated with the framework that pertain to the phenomenon of interest. Another way to identify a theoretical framework is self-reflection by the researcher on personal beliefs and understandings about the nature of knowledge the researcher brings to the study ( Lysaght, 2011 ). In stating one’s beliefs and understandings related to the study (e.g., students construct their knowledge, instructional materials support learning), an orientation becomes evident that will suggest a particular theoretical framework. Theoretical frameworks are not arbitrary , but purposefully selected.

With experience, a researcher may find expanded roles for theoretical frameworks. Researchers may revise an existing framework that has limited explanatory power, or they may decide there is a need to develop a new theoretical framework. These frameworks can emerge from a current study or the need to explain a phenomenon in a new way. Researchers may also find that multiple theoretical frameworks are necessary to frame and explore a problem, as different frameworks can provide different insights into a problem.

Finally, it is important to recognize that choosing “x” theoretical framework does not necessarily mean a researcher chooses “y” methodology and so on, nor is there a clear-cut, linear process in selecting a theoretical framework for one’s study. In part, the nonlinear process of identifying a theoretical framework is what makes understanding and using theoretical frameworks challenging. For the novice scholar, contemplating and understanding theoretical frameworks is essential. Fortunately, there are articles and books that can help:

• Creswell, J. W. (2018). Research design: Qualitative, quantitative, and mixed methods approaches (5th ed.). Los Angeles, CA: Sage. This book provides an overview of theoretical frameworks in general educational research.
• Ding, L. (2019). Theoretical perspectives of quantitative physics education research. Physical Review Physics Education Research , 15 (2), 020101-1–020101-13. This paper illustrates how a DBER field can use theoretical frameworks.
• Nehm, R. (2019). Biology education research: Building integrative frameworks for teaching and learning about living systems. Disciplinary and Interdisciplinary Science Education Research , 1 , ar15. https://doi.org/10.1186/s43031-019-0017-6 . This paper articulates the need for studies in BER to explicitly state theoretical frameworks and provides examples of potential studies.
• Patton, M. Q. (2015). Qualitative research & evaluation methods: Integrating theory and practice . Sage. This book also provides an overview of theoretical frameworks, but for both research and evaluation.

CONCEPTUAL FRAMEWORKS

Purpose of a conceptual framework.

A conceptual framework is a description of the way a researcher understands the factors and/or variables that are involved in the study and their relationships to one another. The purpose of a conceptual framework is to articulate the concepts under study using relevant literature ( Rocco and Plakhotnik, 2009 ) and to clarify the presumed relationships among those concepts ( Rocco and Plakhotnik, 2009 ; Anfara and Mertz, 2014 ). Conceptual frameworks are different from theoretical frameworks in both their breadth and grounding in established findings. Whereas a theoretical framework articulates the lens through which a researcher views the work, the conceptual framework is often more mechanistic and malleable.

Conceptual frameworks are broader, encompassing both established theories (i.e., theoretical frameworks) and the researchers’ own emergent ideas. Emergent ideas, for example, may be rooted in informal and/or unpublished observations from experience. These emergent ideas would not be considered a “theory” if they are not yet tested, supported by systematically collected evidence, and peer reviewed. However, they do still play an important role in the way researchers approach their studies. The conceptual framework allows authors to clearly describe their emergent ideas so that connections among ideas in the study and the significance of the study are apparent to readers.

Constructing Conceptual Frameworks

Including a conceptual framework in a research study is important, but researchers often opt to include either a conceptual or a theoretical framework. Either may be adequate, but both provide greater insight into the research approach. For instance, a research team plans to test a novel component of an existing theory. In their study, they describe the existing theoretical framework that informs their work and then present their own conceptual framework. Within this conceptual framework, specific topics portray emergent ideas that are related to the theory. Describing both frameworks allows readers to better understand the researchers’ assumptions, orientations, and understanding of concepts being investigated. For example, Connolly et al. (2018) included a conceptual framework that described how they applied a theoretical framework of social cognitive career theory (SCCT) to their study on teaching programs for doctoral students. In their conceptual framework, the authors described SCCT, explained how it applied to the investigation, and drew upon results from previous studies to justify the proposed connections between the theory and their emergent ideas.

In some cases, authors may be able to sufficiently describe their conceptualization of the phenomenon under study in an introduction alone, without a separate conceptual framework section. However, incomplete descriptions of how the researchers conceptualize the components of the study may limit the significance of the study by making the research less intelligible to readers. This is especially problematic when studying topics in which researchers use the same terms for different constructs or different terms for similar and overlapping constructs (e.g., inquiry, teacher beliefs, pedagogical content knowledge, or active learning). Authors must describe their conceptualization of a construct if the research is to be understandable and useful.

There are some key areas to consider regarding the inclusion of a conceptual framework in a study. To begin with, it is important to recognize that conceptual frameworks are constructed by the researchers conducting the study ( Rocco and Plakhotnik, 2009 ; Maxwell, 2012 ). This is different from theoretical frameworks that are often taken from established literature. Researchers should bring together ideas from the literature, but they may be influenced by their own experiences as a student and/or instructor, the shared experiences of others, or thought experiments as they construct a description, model, or representation of their understanding of the phenomenon under study. This is an exercise in intellectual organization and clarity that often considers what is learned, known, and experienced. The conceptual framework makes these constructs explicitly visible to readers, who may have different understandings of the phenomenon based on their prior knowledge and experience. There is no single method to go about this intellectual work.

Reeves et al. (2016) is an example of an article that proposed a conceptual framework about graduate teaching assistant professional development evaluation and research. The authors used existing literature to create a novel framework that filled a gap in current research and practice related to the training of graduate teaching assistants. This conceptual framework can guide the systematic collection of data by other researchers because the framework describes the relationships among various factors that influence teaching and learning. The Reeves et al. (2016) conceptual framework may be modified as additional data are collected and analyzed by other researchers. This is not uncommon, as conceptual frameworks can serve as catalysts for concerted research efforts that systematically explore a phenomenon (e.g., Reynolds et al. , 2012 ; Brownell and Kloser, 2015 ).

Sabel et al. (2017) used a conceptual framework in their exploration of how scaffolds, an external factor, interact with internal factors to support student learning. Their conceptual framework integrated principles from two theoretical frameworks, self-regulated learning and metacognition, to illustrate how the research team conceptualized students’ use of scaffolds in their learning ( Figure 1 ). Sabel et al. (2017) created this model using their interpretations of these two frameworks in the context of their teaching.

Conceptual framework from Sabel et al. (2017) .

A conceptual framework should describe the relationship among components of the investigation ( Anfara and Mertz, 2014 ). These relationships should guide the researcher’s methods of approaching the study ( Miles et al. , 2014 ) and inform both the data to be collected and how those data should be analyzed. Explicitly describing the connections among the ideas allows the researcher to justify the importance of the study and the rigor of the research design. Just as importantly, these frameworks help readers understand why certain components of a system were not explored in the study. This is a challenge in education research, which is rooted in complex environments with many variables that are difficult to control.

For example, Sabel et al. (2017) stated: “Scaffolds, such as enhanced answer keys and reflection questions, can help students and instructors bridge the external and internal factors and support learning” (p. 3). They connected the scaffolds in the study to the three dimensions of metacognition and the eventual transformation of existing ideas into new or revised ideas. Their framework provides a rationale for focusing on how students use two different scaffolds, and not on other factors that may influence a student’s success (self-efficacy, use of active learning, exam format, etc.).

In constructing conceptual frameworks, researchers should address needed areas of study and/or contradictions discovered in literature reviews. By attending to these areas, researchers can strengthen their arguments for the importance of a study. For instance, conceptual frameworks can address how the current study will fill gaps in the research, resolve contradictions in existing literature, or suggest a new area of study. While a literature review describes what is known and not known about the phenomenon, the conceptual framework leverages these gaps in describing the current study ( Maxwell, 2012 ). In the example of Sabel et al. (2017) , the authors indicated there was a gap in the literature regarding how scaffolds engage students in metacognition to promote learning in large classes. Their study helps fill that gap by describing how scaffolds can support students in the three dimensions of metacognition: intelligibility, plausibility, and wide applicability. In another example, Lane (2016) integrated research from science identity, the ethic of care, the sense of belonging, and an expertise model of student success to form a conceptual framework that addressed the critiques of other frameworks. In a more recent example, Sbeglia et al. (2021) illustrated how a conceptual framework influences the methodological choices and inferences in studies by educational researchers.

Sometimes researchers draw upon the conceptual frameworks of other researchers. When a researcher’s conceptual framework closely aligns with an existing framework, the discussion may be brief. For example, Ghee et al. (2016) referred to portions of SCCT as their conceptual framework to explain the significance of their work on students’ self-efficacy and career interests. Because the authors’ conceptualization of this phenomenon aligned with a previously described framework, they briefly mentioned the conceptual framework and provided additional citations that provided more detail for the readers.

Within both the BER and the broader DBER communities, conceptual frameworks have been used to describe different constructs. For example, some researchers have used the term “conceptual framework” to describe students’ conceptual understandings of a biological phenomenon. This is distinct from a researcher’s conceptual framework of the educational phenomenon under investigation, which may also need to be explicitly described in the article. Other studies have presented a research logic model or flowchart of the research design as a conceptual framework. These constructions can be quite valuable in helping readers understand the data-collection and analysis process. However, a model depicting the study design does not serve the same role as a conceptual framework. Researchers need to avoid conflating these constructs by differentiating the researchers’ conceptual framework that guides the study from the research design, when applicable.

Explicitly describing conceptual frameworks is essential in depicting the focus of the study. We have found that being explicit in a conceptual framework means using accepted terminology, referencing prior work, and clearly noting connections between terms. This description can also highlight gaps in the literature or suggest potential contributions to the field of study. A well-elucidated conceptual framework can suggest additional studies that may be warranted. This can also spur other researchers to consider how they would approach the examination of a phenomenon and could result in a revised conceptual framework.

It can be challenging to create conceptual frameworks, but they are important. Below are two resources that could be helpful in constructing and presenting conceptual frameworks in educational research:

• Maxwell, J. A. (2012). Qualitative research design: An interactive approach (3rd ed.). Los Angeles, CA: Sage. Chapter 3 in this book describes how to construct conceptual frameworks.
• Ravitch, S. M., & Riggan, M. (2016). Reason & rigor: How conceptual frameworks guide research . Los Angeles, CA: Sage. This book explains how conceptual frameworks guide the research questions, data collection, data analyses, and interpretation of results.

CONCLUDING THOUGHTS

Literature reviews, theoretical frameworks, and conceptual frameworks are all important in DBER and BER. Robust literature reviews reinforce the importance of a study. Theoretical frameworks connect the study to the base of knowledge in educational theory and specify the researcher’s assumptions. Conceptual frameworks allow researchers to explicitly describe their conceptualization of the relationships among the components of the phenomenon under study. Table 1 provides a general overview of these components in order to assist biology education researchers in thinking about these elements.

It is important to emphasize that these different elements are intertwined. When these elements are aligned and complement one another, the study is coherent, and the study findings contribute to knowledge in the field. When literature reviews, theoretical frameworks, and conceptual frameworks are disconnected from one another, the study suffers. The point of the study is lost, suggested findings are unsupported, or important conclusions are invisible to the researcher. In addition, this misalignment may be costly in terms of time and money.

Conducting a literature review, selecting a theoretical framework, and building a conceptual framework are some of the most difficult elements of a research study. It takes time to understand the relevant research, identify a theoretical framework that provides important insights into the study, and formulate a conceptual framework that organizes the finding. In the research process, there is often a constant back and forth among these elements as the study evolves. With an ongoing refinement of the review of literature, clarification of the theoretical framework, and articulation of a conceptual framework, a sound study can emerge that makes a contribution to the field. This is the goal of BER and education research.

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This chapter provides the theoretical backdrop of the study, giving an overview of existing approaches and describing empirical results in the literature. The first section briefly discusses the concept of institutions and describes insights from institutional theory. This section addresses the theoretical relationship between institutions and individuals and the question of how institutions impact on human behavior, preferences, and attitudes.

• Welfare State
• Parental Leave
• Normative Belief
• Family Policy
• Welfare Regime

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For critics and extensions made by other scholars, please refer to Leibfried (1992), Castles and Mitchell (1993), Ferrera (1996), Bonoli (1997), Arts and Gelissen (2002), and Scruggs and Allen (2006).

See Ferrarini (2006: Chpt. 3 ) for a thorough analysis of the political determinants of familypolicy development, such as class-political factors and women’s role in political decision making.

An exception might be the group of migrant families. However, the topic of migration and the social rights of migrants, e.g., in terms welfare state entitlements go beyond the scope of this study. For a discussion of these issues, see Alesina and Glaeser (2004) and Mau and Burkhardt (2009).

The idea of subsidiarity implies “that social services should be provided for at the lowest possible level in the community, public authorities playing a role only in the event that churches and families are unable to do so” (Fagnani 2007: 43).

I.e., “when a service is rendered as a matter of right, and when a person can maintain a livelihood without reliance on the market” (Esping-Andersen 1990: 21/22).

For a discussion of the distinctiveness of the Southern European countries, see also Ferrara (1996) and Karamessini (2008), who discussed the distinctiveness of this group of countries with respect to several fields of welfare-state intervention.

After the Second World War, Germany was divided into two countries. Between 1949 and 1989, the “German Democratic Republic” (East Germany) had a state socialist system with a centrally planned economy with socialist employment and family policies, whereas the “Federal Republic of Germany” (West Germany) had a multi-party parliament, a market economy, and a conservative-corporatist welfare state (Rosenfeld et al. 2004: 103).

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Mischke, M. (2014). Theoretical background and literature review. In: Public Attitudes towards Family Policies in Europe. Springer VS, Wiesbaden. https://doi.org/10.1007/978-3-658-03577-8_2

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• Published: 05 December 2023

A scoping review to identify and organize literature trends of bias research within medical student and resident education

• Brianne E. Lewis 1 &
• Akshata R. Naik 2  

BMC Medical Education volume  23 , Article number:  919 ( 2023 ) Cite this article

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Physician bias refers to the unconscious negative perceptions that physicians have of patients or their conditions. Medical schools and residency programs often incorporate training to reduce biases among their trainees. In order to assess trends and organize available literature, we conducted a scoping review with a goal to categorize different biases that are studied within medical student (MS), resident (Res) and mixed populations (MS and Res). We also characterized these studies based on their research goal as either documenting evidence of bias (EOB), bias intervention (BI) or both. These findings will provide data which can be used to identify gaps and inform future work across these criteria.

Online databases (PubMed, PsycINFO, WebofScience) were searched for articles published between 1980 and 2021. All references were imported into Covidence for independent screening against inclusion criteria. Conflicts were resolved by deliberation. Studies were sorted by goal: ‘evidence of bias’ and/or ‘bias intervention’, and by population (MS or Res or mixed) andinto descriptive categories of bias.

Of the initial 806 unique papers identified, a total of 139 articles fit the inclusion criteria for data extraction. The included studies were sorted into 11 categories of bias and showed that bias against race/ethnicity, specific diseases/conditions, and weight were the most researched topics. Of the studies included, there was a higher ratio of EOB:BI studies at the MS level. While at the Res level, a lower ratio of EOB:BI was found.

Conclusions

This study will be of interest to institutions, program directors and medical educators who wish to specifically address a category of bias and identify where there is a dearth of research. This study also underscores the need to introduce bias interventions at the MS level.

Peer Review reports

Physician bias ultimately impacts patient care by eroding the physician–patient relationship [ 1 , 2 , 3 , 4 ]. To overcome this issue, certain states require physicians to report a varying number of hours of implicit bias training as part of their recurring licensing requirement [ 5 , 6 ]. Research efforts on the influence of implicit bias on clinical decision-making gained traction after the “Unequal Treatment: Confronting Racial and Ethnic Disparities in Health Care” report published in 2003 [ 7 ]. This report sparked a conversation about the impact of bias against women, people of color, and other marginalized groups within healthcare. Bias from a healthcare provider has been shown to affect provider-patient communication and may also influence treatment decisions [ 8 , 9 ]. Nevertheless, opportunities within medical education curriculum are created to evaluate biases at an earlier stage of physician-training and provide instruction to intervene them [ 10 , 11 , 12 ]. We aimed to identify trends and organize literature on bias training provided during medical school and residency programs since the meaning of ‘bias’ is broad and encompasses several types of attitudes and predispositions [ 13 ].

Several reviews, narrative or systematic in nature, have been published in the field of bias research in medicine and healthcare [ 14 , 15 , 16 ]. Many of these reviews have a broad focus on implicit bias and they often fail to define the patient’s specific attributes- such as age, weight, disease, or condition against which physicians hold their biases. However, two recently published reviews categorized implicit biases into various descriptive characteristics albeit with research goals different than this study [ 17 , 18 ]. The study by Fitzgerald et al. reviewed literature focused on bias among physicians and nurses to highlight its role in healthcare disparities [ 17 ]. While the study by Gonzalez et al. focused on bias curricular interventions across professions related to social determinants of health such as education, law, medicine and social work [ 18 ]. Our research goal was to identify the various bias characteristics that are studied within medical student and/or resident populations and categorize them. Further, we were interested in whether biases were merely identified or if they were intervened. To address these deficits in the field and provide clarity, we utilized a scoping review approach to categorize the literature based on a) the bias addressed and b) the study goal within medical students (MS), residents (Res) and a mixed population (MS and Res).

To date no literature review has organized bias research by specific categories held solely by medical trainees (medical students and/or residents) and quantified intervention studies. We did not perform a quality assessment or outcome evaluation of the bias intervention strategies, as it was not the goal of this work and is standard with a scoping review methodology [ 19 , 20 ]. By generating a comprehensive list of bias categories researched among medical trainee population, we highlight areas of opportunity for future implicit bias research specifically within the undergraduate and graduate medical education curriculum. We anticipate that the results from this scoping review will be useful for educators, administrators, and stakeholders seeking to implement active programs or workshops that intervene specific biases in pre-clinical medical education and prepare physicians-in-training for patient encounters. Additionally, behavioral scientists who seek to support clinicians, and develop debiasing theories [ 21 ] and models may also find our results informative.

We conducted an exhaustive and focused scoping review and followed the methodological framework for scoping reviews as previously described in the literature [ 20 , 22 ]. This study aligned with the four goals of a scoping review [ 20 ]. We followed the first five out of the six steps outlined by Arksey and O’Malley’s to ensure our review’s validity 1) identifying the research question 2) identifying relevant studies 3) selecting the studies 4) charting the data and 5) collating, summarizing and reporting the results [ 22 ]. We did not follow the optional sixth step of undertaking consultation with key stakeholders as it was not needed to address our research question it [ 23 ]. Furthermore, we used Covidence systematic review software (Veritas Health Innovation, Melbourne, Australia) that aided in managing steps 2–5 presented above.

Research question, search strategy and inclusion criteria

The purpose of this study was to identify trends in bias research at the medical school and residency level. Prior to conducting our literature search we developed our research question and detailed the inclusion criteria, and generated the search syntax with the assistance from a medical librarian. Search syntax was adjusted to the requirements of the database. We searched PubMed, Web of Science, and PsycINFO using MeSH terms shown below.

Bias* [ti] OR prejudice*[ti] OR racism[ti] OR homophobia[ti] OR mistreatment[ti] OR sexism[ti] OR ageism[ti]) AND (prejudice [mh] OR "Bias"[Mesh:NoExp]) AND (Education, Medical [mh] OR Schools, Medical [mh] OR students, medical [mh] OR Internship and Residency [mh] OR “undergraduate medical education” OR “graduate medical education” OR “medical resident” OR “medical residents” OR “medical residency” OR “medical residencies” OR “medical schools” OR “medical school” OR “medical students” OR “medical student”) AND (curriculum [mh] OR program evaluation [mh] OR program development [mh] OR language* OR teaching OR material* OR instruction* OR train* OR program* OR curricul* OR workshop*

Our inclusion criteria incorporated studies which were either original research articles, or review articles that synthesized new data. We excluded publications that were not peer-reviewed or supported with data such as narrative reviews, opinion pieces, editorials, perspectives and commentaries. We included studies outside of the U.S. since the purpose of this work was to generate a comprehensive list of biases. Physicians, regardless of their country of origin, can hold biases against specific patient attributes [ 17 ]. Furthermore, physicians may practice in a different country than where they trained [ 24 ]. Manuscripts were included if they were published in the English language for which full-texts were available. Since the goal of this scoping review was to assess trends, we accepted studies published from 1980–2021.

Our inclusion criteria also considered the goal and the population of the study. We defined the study goal as either that documented evidence of bias or a program directed bias intervention. Evidence of bias (EOB) had to originate from the medical trainee regarding a patient attribute. Bias intervention (BI) studies involved strategies to counter biases such as activities, workshops, seminars or curricular innovations. The population studied had to include medical students (MS) or residents (Res) or mixed. We defined the study population as ‘mixed’ when it consisted of both MS and Res. Studies conducted on other healthcare professionals were included if MS or Res were also studied. Our search criteria excluded studies that documented bias against medical professionals (students, residents and clinicians) either by patients, medical schools, healthcare administrators or others, and was focused on studies where the biases were solely held by medical trainees (MS and Res).

Data extraction and analysis

Following the initial database search, references were downloaded and bulk uploaded into Covidence and duplicates were removed. After the initial screening of title and abstracts, full-texts were reviewed. Authors independently completed title and abstract screening, and full text reviews. Any conflicts at the stage of abstract screening were moved to full-text screening. Conflicts during full-text screening were resolved by deliberation and referring to the inclusion and exclusion criteria detailed in the research protocol. The level of agreement between the two authors for full text reviews as measured by inter-rater reliability was 0.72 (Cohen’s Kappa).

A data extraction template was created in Covidence to extract data from included full texts. Data extraction template included the following variables; country in which the study was conducted, year of publication, goal of the study (EOB, BI or both), population of the study (MS, Res or mixed) and the type of bias studied. Final data was exported to Microsoft Excel for quantification. For charting our data and categorizing the included studies, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews(PRISMA-ScR) guidelines [ 25 ]. Results from this scoping review study are meant to provide a visual synthesis of existing bias research and identify gaps in knowledge.

Study selection

Our search strategy yielded a total of 892 unique abstracts which were imported into ‘Covidence’ for screening. A total of 86 duplicate references were removed. Then, 806 titles and abstracts were screened for relevance independently by the authors and 519 studies were excluded at this stage. Any conflicts among the reviewers at this stage were resolved by discussion and referring to the inclusion and exclusion criteria. Then a full text review of the remaining 287 papers was completed by the authors against the inclusion criteria for eligibility. Full text review was also conducted independently by the authors and any conflicts were resolved upon discussion. Finally, we included 139 studies which were used for data extraction (Fig.  1 ).

PRISMA diagram of the study selection process used in our scoping review to identify the bias categories that have been reported within medical education literature. Study took place from 2021–2022. Abbreviation: PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses

Publication trends in bias research

First, we charted the studies to demonstrate the timeline of research focused on bias within the study population of our interest (MS or Res or mixed). Our analysis revealed an increase in publications with respect to time (Fig.  2 ). Of the 139 included studies, fewer studies were published prior to 2001, with a total of only eight papers being published from the years 1985–2000. A substantial increase in publications occurred after 2004, with 2019 being the peak year where most of the studies pertaining to bias were published (Fig.  2 ).

Studies matching inclusion criteria mapped by year of publication. Search criteria included studies addressing bias from 1980–2021 within medical students (MS) or residents (Res) or mixed (MS + Res) populations. * Publication in 2022 was published online ahead of print

Overview of included studies

We present a descriptive analysis of the 139 included studies in Table 1 based on the following parameters: study location, goal of the study, population of the study and the category of bias studied. All of the above parameters except the category of bias included a denominator of 139 studies. Several studies addressed more than one bias characteristic; therefore, we documented 163 biases sorted in 11 categories over the 139 papers. The bias categories that we generated and their respective occurrences are listed in Table 1 . Of the 139 studies that were included, most studies originated in the United States ( n  = 89/139, 64%) and Europe ( n  = 20/139, 20%).

Sorting of included research by bias category

We grouped the 139 included studies depending on the patient attribute or the descriptive characteristic against which the bias was studied (Table 1 ). By sorting the studies into different bias categories, we aimed to not only quantitate the amount of research addressing a particular topic of bias, but also reveal the biases that are understudied.

Through our analysis, we generated 11 descriptive categories against which bias was studied: Age, physical disability, education level, biological sex, disease or condition, LGBTQ + , non-specified, race/ethnicity, rural/urban, socio-economic status, and weight (Table 1 ). “Age” and “weight” categories included papers that studied bias against older population and higher weight individuals, respectively. The categories “education level” and “socio-economic status” included papers that studied bias against individuals with low education level and individuals belonging to low socioeconomic status, respectively. Within the bias category named ‘biological sex’, we included papers that studied bias against individuals perceived as women/females. Papers that studied bias against gender-identity or sexual orientation were included in its own category named, ‘LGBTQ + ’. The bias category, ‘disease or condition’ was broad and included research on bias against any patient with a specific disease, condition or lifestyle. Studies included in this category researched bias against any physical illnesses, mental illnesses, or sexually transmitted infections. It also included studies that addressed bias against a treatment such as transplant or pain management. It was not significant to report these as individual categories but rather as a whole with a common underlying theme. Rural/urban bias referred to bias that was held against a person based on their place of residence. Studies grouped together in the ‘non-specified bias’ category explored bias without specifying any descriptive characteristic in their methods. These studies did not address any specific bias characteristic in particular but consisted of a study population of our interest (MS or Res or mixed). Based on our analysis, the top five most studied bias categories in our included population within medical education literature were: racial or ethnic bias ( n  = 39/163, 24%), disease or condition bias ( n  = 29/163, 18%), weight bias ( n  = 22/163, 13%), LGBTQ + bias ( n  = 21/163, 13%), and age bias ( n  = 16/163, 10%) which are presented in Table 1 .

Sorting of included research by population

In order to understand the distribution of bias research based on their populations examined, we sorted the included studies in one of the following: medical students (MS), residents (Res) or mixed (Table 1 ). The following distributions were observed: medical students only ( n  = 105/139, 76%), residents only ( n  = 19/139, 14%) or mixed which consisted of both medical students and residents ( n  = 15/139, 11%). In combination, these results demonstrate that medical educators have focused bias research efforts primarily on medical student populations.

Sorting of included research by goal

A critical component of this scoping review was to quantify the research goal of the included studies within each of the bias categories. We defined the research goal as either to document evidence of bias (EOB) or to evaluate a bias intervention (BI) (see Fig.  1 for inclusion criteria). Some of the included studies focused on both, documenting evidence in addition to intervening biases and those studies were grouped separately. The analysis revealed that 69/139 (50%) of the included studies focused exclusively on documenting evidence of bias (EOB). There were fewer studies ( n  = 51/139, 37%) which solely focused on bias interventions such as programs, seminars or curricular innovations. A small minority of the included studies were more comprehensive in that they documented EOB followed by an intervention strategy ( n  = 19/139, 11%). These results demonstrate that most bias research is dedicated to documenting evidence of bias among these groups rather than evaluating a bias intervention strategy.

Research goal distribution

Our next objective was to calculate the distribution of studies with respect to the study goal (EOB, BI or both), within the 163 biases studied across the 139 papers as calculated in Table 1 . In general, the goal of the studies favors documenting evidence of bias with the exception of race/ethnic bias which is more focused on bias intervention (Fig.  3 ). Fewer studies were aimed at both, documenting evidence then providing an intervention, across all bias categories.

Sorting of total biases ( n  = 163) within medical students or residents or a mixed population based on the bias category . Dark grey indicates studies with a dual goal, to document evidence of bias and to intervene bias. Medium grey bars indicate studies which focused on documenting evidence of bias. Light grey bars indicate studies focused on bias intervention within these populations. Numbers inside the bars indicate the total number of biases for the respective study goal. * Non-specified bias includes studies which focused on implicit bias but did not mention the type of bias investigated

Furthermore, we also calculated the ratio of EOB, BI and both (EOB + BI) within each of our population of interest (MS; n  = 122, Res; n  = 26 and mixed; n  = 15) for the 163 biases observed in our included studies. Over half ( n  = 64/122, 52%) of the total bias occurrences in MS were focused on documenting EOB (Fig.  4 ). Contrastingly, a shift was observed within resident populations where most biases addressed were aimed at intervention ( n  = 12/26, 41%) rather than EOB ( n  = 4/26, 14%) (Fig.  4 ). Studies which included both MS and Res (mixed) were primarily focused on documenting EOB ( n  = 9/15, 60%), with 33% ( n  = 5/15) aimed at bias intervention and 7% ( n  = 1/15) which did both (Fig.  4 ). Although far fewer studies were documented in the Res population it is important to highlight that most of these studies were focused on bias intervention when compared to MS population where we documented a majority of studies focused on evidence of bias.

A ratio of the study goal for the total biases ( n  = 163) mapped within each of the study population (MS, Res and Mixed). A study goal with a) documenting evidence of bias (EOB) is depicted in dotted grey, b) bias intervention (BI) in medium grey, and c) a dual focus (EOB + BI) is depicted in dark grey. * N  = 122 for medical student studies. b N  = 26 for residents. c N  = 15 for mixed

Addressing biases at an earlier stage of medical career is critical for future physicians engaging with diverse patients, since it is established that bias negatively influences provider-patient interactions [ 171 ], clinical decision-making [ 172 ] and reduces favorable treatment outcomes [ 2 ]. We set out with an intention to explore how bias is addressed within the medical curriculum. Our research question was: how has the trend in bias research changed over time, more specifically a) what is the timeline of papers published? b) what bias characteristics have been studied in the physician-trainee population and c) how are these biases addressed? With the introduction of ‘standards of diversity’ by the Liaison Committee on Medical Education, along with the Association of American Medical Colleges (AAMC) and the American Medical Association (AMA) [ 173 , 174 ], we certainly expected and observed a sustained uptick in research pertaining to bias. As shown here, research addressing bias in the target population (MS and Res) is on the rise, however only 139 papers fit our inclusion criteria. Of these studies, nearly 90% have been published since 2005 after the “Unequal Treatment: Confronting Racial and Ethnic Disparities in Health Care” report was published in 2003 [ 7 ]. However, given the well documented effects of physician held bias, we anticipated significantly more number of studies focused on bias at the medical student or resident level.

A key component from this study was that we generated descriptive categories of biases. Sorting the biases into descriptive categories helps to identify a more targeted approach for a specific bias intervention, rather than to broadly intervene bias as a whole. In fact, our analysis found a number of publications (labeled “non-specified bias” in Table 1 ) which studied implicit bias without specifying the patient attribute or the characteristic that the bias was against. In total, we generated 11 descriptive categories of bias from our scoping review which are shown in Table 1 and Fig.  3 . Furthermore, our bias descriptors grouped similar kinds of biases within a single category. For example, the category, “disease or condition” included papers that studied bias against any type of disease (Mental illness, HIV stigma, diabetes), condition (Pain management), or lifestyle. We neither performed a qualitative assessment of the studies nor did we test the efficacy of the bias intervention studies and consider it a future direction of this work.

Evidence suggests that medical educators and healthcare professionals are struggling to find the appropriate approach to intervene biases [ 175 , 176 , 177 ] So far, bias reduction, bias reflection and bias management approaches have been proposed [ 26 , 27 , 178 ]. Previous implicit bias intervention strategies have been shown to be ineffective when biased attitudes of participants were assessed after a lag [ 179 ]. Understanding the descriptive categories of bias and previous existing research efforts, as we present here is only a fraction of the challenge. The theory of “cognitive bias” [ 180 ] and related branches of research [ 13 , 181 , 182 , 183 , 184 ] have been studied in the field of psychology for over three decades. It is only recently that cognitive bias theory has been applied to the field of medical education medicine, to explain its negative influence on clinical decision-making pertaining only to racial minorities [ 1 , 2 , 15 , 16 , 17 , 185 ]. In order to elicit meaningful changes with respect to targeted bias intervention, it is necessary to understand the psychological underpinnings (attitudes) leading to a certain descriptive category of bias (behaviors). The questions which medical educators need to ask are: a) Can these descriptive biases be identified under certain type/s of cognitive errors that elicits the bias and vice versa b) Are we working towards an attitude change which can elicit a sustained positive behavior change among healthcare professionals? And most importantly, c) are we creating a culture where participants voluntarily enroll themselves in bias interventions as opposed to being mandated to participate? Cognitive psychologists and behavioral scientists are well-positioned to help us find answers to these questions as they understand human behavior. Therefore, an interdisciplinary approach, a marriage between cognitive psychologists and medical educators, is key in targeting biases held by medical students, residents, and ultimately future physicians. This review may also be of interest to behavioral psychologists, keen on providing targeted intervening strategies to clinicians depending on the characteristics (age, weight, sex or race) the portrayed bias is against. Further, instead of an individualized approach, we need to strive for systemic changes and evidence-based strategies to intervene biases.

The next element in change is directing intervention strategies at the right stage in clinical education. Our study demonstrated that most of the research collected at the medical student level was focused on documenting evidence of bias. Although the overall number of studies at the resident level were fewer than at the medical student level, the ratio of research in favor of bias intervention was higher at the resident level (see Fig.  3 ). However, it could be helpful to focus on bias intervention earlier in learning, rather than at a later stage [ 186 ]. Additionally, educational resources such as textbooks, preparatory materials, and educators themselves are potential sources of propagating biases and therefore need constant evaluation against best practices [ 187 , 188 ].

This study has limitations. First, the list of the descriptive bias categories that we generated was not grounded in any particular theory so assigning a category was subjective. Additionally, there were studies that were categorized as “nonspecified” bias as the studies themselves did not mention the specific type of bias that they were addressing. Moreover, we had to exclude numerous publications solely because they were not evidence-based and were either perspectives, commentaries or opinion pieces. Finally, there were overall fewer studies focused on the resident population, so the calculated ratio of MS:Res studies did not compare similar sample sizes.

Future directions of our study include working with behavioral scientists to categorize these bias characteristics (Table 1 ) into cognitive error types [ 189 ]. Additionally, we aim to assess the effectiveness of the intervention strategies and categorize the approach of the intervention strategies.

The primary goal of our review was to organize, compare and quantify literature pertaining to bias within medical school curricula and residency programs. We neither performed a qualitative assessment of the studies nor did we test the efficacy of studies that were sorted into “bias intervention” as is typical of scoping reviews [ 22 ]. In summary, our research identified 11 descriptive categories of biases studied within medical students and resident populations with “race and ethnicity”, “disease or condition”, “weight”, “LGBTQ + ” and “age” being the top five most studied biases. Additionally, we found a greater number of studies conducted in medical students (105/139) when compared to residents (19/139). However, most of the studies in the resident population focused on bias intervention. The results from our review highlight the following gaps: a) bias categories where more research is needed, b) biases that are studied within medical school versus in residency programs and c) study focus in terms of demonstrating the presence of bias or working towards bias intervention.

This review provides a visual analysis of the known categories of bias addressed within the medical school curriculum and in residency programs in addition to providing a comparison of studies with respect to the study goal within medical education literature. The results from our review should be of interest to community organizations, institutions, program directors and medical educators interested in knowing and understanding the types of bias existing within healthcare populations. It might be of special interest to researchers who wish to explore other types of biases that have been understudied within medical school and resident populations, thus filling the gaps existing in bias research.

Despite the number of studies designed to provide bias intervention for MS and Res populations, and an overall cultural shift to be aware of one’s own biases, biases held by both medical students and residents still persist. Further, psychologists have recently demonstrated the ineffectiveness of some bias intervention efforts [ 179 , 190 ]. Therefore, it is perhaps unrealistic to expect these biases to be eliminated altogether. However, effective intervention strategies grounded in cognitive psychology should be implemented earlier on in medical training. Our focus should be on providing evidence-based approaches and safe spaces for an attitude and culture change, so as to induce actionable behavioral changes.

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Abbreviations

• Medical student

Evidence of bias

• Bias intervention

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Acknowledgements

The authors would like to thank Dr. Misa Mi, Professor and Medical Librarian at the Oakland University William Beaumont School of Medicine (OWUB) for her assistance with selection of databases and construction of literature search strategies for the scoping review. The authors also wish to thank Dr. Changiz Mohiyeddini, Professor in Behavioral Medicine and Psychopathology at Oakland University William Beaumont School of Medicine (OUWB) for his expertise and constructive feedback on our manuscript.

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Lewis, B.E., Naik, A.R. A scoping review to identify and organize literature trends of bias research within medical student and resident education. BMC Med Educ 23 , 919 (2023). https://doi.org/10.1186/s12909-023-04829-6

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Super-refractory status epilepticus, rhabdomyolysis, central hyperthermia and cardiomyopathy attributable to spinal anesthesia: a case report and review of literature

• N. D.B. Ehelepola   ORCID: orcid.org/0000-0001-9133-2307 1 ,
• R. M.D.C. Ranathunga 1 ,
• A. B. Abeysundara 1 , 2 ,
• H. M.R.P. Jayawardana 1 &
• P. S.K. Nanayakkara 1 , 2  

BMC Anesthesiology volume  24 , Article number:  132 ( 2024 ) Cite this article

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Metrics details

There are only six past reports of super-refractory status epilepticus induced by spinal anesthesia. None of those patients have died. Only < 15 mg of bupivacaine was administered to all six of them and to our case. Pathophysiology ensuing such cases remains unclear.

Case presentation

A 27 year old gravida 2, para 1, mother at 37 weeks of gestation came to the operating theater for an elective cesarean section. She had no significant medical history other than controlled hypothyroidism and one episode of food allergy. Her current pregnancy was uneventful. Her American Society of Anesthesiologists (ASA) grade was 2. She underwent spinal anesthesia and adequate anesthesia was achieved. After 5–7 min she developed a progressive myoclonus. After delivery of a healthy baby, she developed generalized tonic clonic seizures that continued despite the induction of general anesthesia. She had rhabdomyolysis, one brief cardiac arrest and resuscitation, followed by stress cardiomyopathy and central hyperthermia. She died on day four. There were no significant macroscopic or histopathological changes in her brain that explain her super refractory status epilepticus. Heavy bupivacaine samples of the same batch used for this patient were analyzed by two specialized laboratories. National Medicines Quality Assurance Laboratory of Sri Lanka reported that samples failed to confirm United States Pharmacopeia (USP) dextrose specifications and passed other tests. Subsequently, Therapeutic Goods Administration of Australia reported that the drug passed all standard USP quality tests applied to it. Nonetheless, they have detected an unidentified impurity in the medicine.

Conclusions

After reviewing relevant literature, we believe that direct neurotoxicity by bupivacaine is the most probable cause of super-refractory status epilepticus. Super-refractory status epilepticus would have led to her other complications and death. We discuss probable patient factors that would have made her susceptible to neurotoxicity. The impurity in the drug detected by one laboratory also would have contributed to her status epilepticus. We propose several possible mechanisms that would have led to status epilepticus and her death. We discuss the factors that shall guide investigators on future such cases. We suggest ways to minimize similar future incidents. This is an idiosyncratic reaction as well.

Graphical Abstract

Peer Review reports

There are only a few past reports on status epilepticus attributed to drugs used for spinal anesthesia [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. Out of those, six past reports are of super-refractory status epilepticus cases attributed to bupivacaine and those patients have recovered [ 1 , 2 , 3 , 4 , 5 , 6 ]. Pathophysiology resulting in such cases notwithstanding only < 15 mg of bupivacaine administered, remains unclear. A status epilepticus that continues for ≥ 24 h despite anesthetic treatment, or recurs on an attempted wean of the anesthetic drugs is defined as super-refractory status epilepticus [ 5 , 8 ]. There are no past reports of the combination of super-refractory status epilepticus, rhabdomyolysis, central hyperthermia and cardiomyopathy resulting in the death of a previously healthy person attributed to a spinal anesthetic agent. This death and a few other subsequent deaths due to drug side effects and the alleged poor quality of the responsible drugs generated a huge outcry in most national news media. Many social media sensationalized the issue and it was debated in Sri Lanka’s parliament as well. That resulted in anxiety among patients undergoing anesthesia, anesthesiology doctors and people utilizing public hospitals. There were some public protests in Sri Lanka in 2023 regarding this issue. This crisis was in the news in some other countries as well [ 9 ].

A 27 year old pregnant woman, height 151 cm, weight 78 kg (Body Mass Index 34.2), in 37 weeks of gestation, came to the operating theater for an elective cesarean section (EL/LSCS) after routine preparation. She is the mother of a five year old child and this is her second pregnancy. Other than hypothyroidism controlled with thyroxin for the past three months she had no significant medical history or history of substance abuse. However, after the below mentioned incident her father told doctors that she had one allergic reaction to pineapple during her childhood which did not require hospital care. Therefore, her ASA grade was 2. She underwent spinal anesthesia in the sitting position, lumbar 4–5 level. A 25G pencil point needle was used. After verification, 2.5 cc of 0.5% heavy bupivacaine = 12.5 mg of bupivacaine (ZUPIVAC H, batch No.DP2203) without adjuvants was administered. Adequate analgesia was achieved up to thoracic dermatome7 level and surgery was started. After 5–7 min, she complained of a backache and a “discomfort” which she could not explain. Then she developed occasional myoclonus in her upper limbs and upper trunk and that once involved legs as well. Myoclonus was momentarily controlled by 2 mg of intravenous (IV) midazolam. Myoclonus progressed in magnitude and frequency. When asked, she denied any circumoral numbness and power of the grip of her both hands was normal. A crying baby was delivered 10 min after anesthesia. Oxytocin was administered and the mother could verbally communicate with the medical officer-anesthesiology. Then her eyes deviated upwards, she could not respond verbally and developed generalized tonic clonic seizures (GTCS). General anesthesia was inducted using thiopentone, she was intubated with suxamethonium and ventilated. Her blood pressure remained 130/80 mmHg − 140/90 mmHg, heart rate in 110–140/min range, ECG(EKG) showed sinus tachycardia, and her peripheries were warm and flushed. ETCO 2 was 55–65 mmHg. Her both pupils were 3 mm and sluggishly reacting to light. Her random blood sugar level was 134 mg/dl. As she developed some bilateral rhonchi (lungs), intravenous (IV) hydrocortisone, chlorpheniramine was administered and she was nebulized with ipratropium. There was uterine atony and bleeding. IV oxyticin, intramuscular ergometrin and per rectal misoprostol were administered and one unit of blood was transfused. Two and a half hours after anesthesia she was taken to the ICU and electively ventilated. Her arterial blood pH was 7.03 and her lactate level was 9.6 mmol/l. Acidosis was corrected with IV sodium bicarbonate. Her chest X ray (CXR) showed a globular heart and haziness in the left lung field, NCCT did not show any abnormality in the brain, protein was +++ in urine; and there was no proteinuria before surgery (many public hospital laboratories of Sri Lanka report proteinuria in a scale from trace to +++. Three + means very high levels). She developed hypotension and norepinephrine infusion was started at 0.3 µg/kg/min rate. She was assessed by consultants/professors in anesthesiology, obstetrics, internal medicine and neurology and by other doctors on the same day. The differential diagnoses of the multi-disciplinary team were an adverse reaction to bupivacaine, amniotic fluid embolism, normotensive eclampsia and previously undiagnosed brain pathology. Our primary goal was to control her seizures while providing life support therapy. She was administered thiopentone, midazolam, MgSO4, levetiracetam, morphine, mannitol and antibiotics etc. Approximately once in four hours thiopentone infusion was withheld to assess her for seizures and to avoid myocardial depression. Atracurium was administered as 25 mg boluses. Whenever the effect of atracurium was weaning she had continuous GTCS on days 1–3 sometimes even while thiopentone was being infused. 20% fat emulsion was not available at our and nearby hospitals at that period of time. Her ETCO 2 remained in 34 -40mmHg range after admission to the ICU.

On the following morning (day 2) she had an episode of bradycardia followed by cardiac arrest and was successfully resuscitated within five minutes. Epinephrine and dopamine infusions were added after this. A 2D echocardiogram performed by one of the ICU doctors did not show hypokinesia in the ventricular walls. Her tachycardia persisted and she developed fever spikes. ST elevations appeared in lead 1, aVL of the ECG(EKG). Therefore, aspirin, clopidogrel and atorvastatin were added. Status epilepticus continued thus levetiracetam dose was increased, IV phenytoin and NG lacosamide were added.

On day3,the seizure frequency decreased. Repeated NCCT did not show any hemorrhages or infarcts in the brain. ST elevations were seen in leads I, aVL, V5-V6 in ECG and troponin I was > 50 ng/ml. Hence, cardiologists opinion was obtained. Creatine kinase (CK) level was 21,420 U/L and alkaline diuresis was started. She had two high fever spikes per day, each > 40 0 C on day 2 and day3.

On day 4, she was seizure free but had hyperpyrexia (once 42.8 0 C) despite active cooling. Lumbar puncture was done and CSF analysis did not show evidence of infection. Same morning she suffered a cardiac arrest, resuscitation was continued for more than an hour but was unsuccessful.

After the drop in day 2, her blood pressure was maintained with three inotropes infused at the following rates. Norepinephrine at 0.3–0.6 µg/kg/min, epinephrine at 0.3–0.6 µg/kg/min and dopamine at 20 − 10 µg/kg/min. Her SpO 2 remained > 92%, her urine output was 40-100 ml/hour and serum creatinine levels were 87–123 micromoles/l during her ICU stay. Her day 1 prothrombin time was 19.2 s and INR was 1.62. Thiopentone would have contributed to this prolongation of INR [ 10 ]. INR was ≤ 1.5 after day 2. Her activated partial thromboplastin time was 26.5 s on day1 and remained normal. EEG and MRI brain could not be done before her death.

The autopsy was performed by a consultant judicial medical officer. Both lungs were congested and exuded frothy fluid on sectioning and the liver was enlarged and soft. No other remarkable abnormalities were detected including in the brain and heart. However, spinal cord was not dissected.

Cerebrum and cerebellum histopathology were unremarkable. Widespread early ischemic changes were seen in the myocardium. Centrilobular necrosis with occasional bridging necrosis in 20% of the liver and mild acute tubular necrosis in the kidneys were seen. Extensive degenerative changes were seen in skeletal muscles. Pulmonary edema, evidence of mild pneumonia and focal hemorrhages were seen in the lungs. Multiple bone marrow emboli were seen in the lungs and heart, consistent with changes associated with prolonged CPR. All changes seen were acute changes.

Samples from all three batches of ZUPIVAC H at our hospital were analyzed by the National Medicines Quality Assurance Laboratory (NMQAL) of Sri Lanka. Samples confirmed USP bupivacaine and other specifications but batch No.s DP 2203 and DP 2202 failed to confirm dextrose specifications. Thereafter, samples were re-analyzed at the Therapeutic Goods Administration (TGA) laboratories of the Australian government. When batch No. DP 2203 was tested according to the relevant USP monograph to validate the medicine and its ingredients, the medicine passed the tests applied to it (it passed the quality test). However, there is no impurity test in the USP monograph. Considering the very unusual and lethal nature of this adverse drug reaction we have requested TGA-Australia look for any impurities as well. Fulfilling our request, they have identified an impurity that is suspected to be structurally related to bupivacaine in batch No. DP 2203. It’s content was estimated to be 0.9% relative to bupivacaine. They have confirmed that this impurity is not mepivacaine. This impurity was not specifically identified in any of the pharmacopoeias available at TGA-Australia. Despite further testing, they were unable to identify what exactly this impurity is. TGA-Australia has noticed another unusual thing. That is although the ZUPIVAC H label claims compliance with the USP for the finished product, they claim compliance with the Indian Pharmacopoeia (IP) for raw materials. The full report is given as a supplementary file.

Discussion and conclusions

Our discussion has eight subheadings. Those are; key facts of the case report, how did we conducted a systematic literature review to find similar reported cases, the relationship of the presented case with the existing literature, circumstantial evidence for and against suspecting heavy bupivacaine (ZUPIVAC H) as the cause of her seizures, explanation of the patient’s clinical and autopsy findings, differential diagnoses we considered at different stages, discussion of central nervous system toxicity by bupivacaine and possible mechanisms of toxicity and lessons to be learned and the way forward.

Key facts of the case report

An ASA grade 2 pregnant mother underwent a routine a spinal anesthesia for a cesarean section and adequate anesthesia was achieved. After 5–7 min, she developed a progressive myoclonus that evolved into generalized tonic clonic seizures after delivery. Her seizures continued despite administering general anesthesia plus multiple anticonvulsants. She had rhabdomyolysis, one brief cardiac arrest, stress cardiomyopathy, central hyperthermia and died on day four. There were no significant radiological, macroscopic or histopathological changes in her brain or biochemical changes that explained her super refractory status epilepticus. Heavy bupivacaine samples from the same batch used for this patient were analyzed by two specialized laboratories. One laboratory reported that samples failed to confirm USP dextrose specifications. Bupivacaine samples passed all standard USP quality tests at the other laboratory. Nevertheless, they managed to detect an unidentified impurity in the medicine.

How did we conducted a systematic literature review to find similar reported cases

Super-refractory status epilepticus is rare and many doctors we know do not use that term. Thus, we decided to search for the word “status epilepticus” and select super-refractory status epilepticus cases out of those. We conducted a literature survey in several online databases in February 2024 for the keywords “status epilepticus”,“spinal anesthesia” and “case report” combined using the Boolean operator “AND”. Those databases were Google Scholar, PubMed, Europe PubMed Central, CNKI, ScienceDirect and DOAJ. A total of 576 articles were identified. Abstracts of each were read and 564 irrelevant articles were excluded. We used the PICO (P: patient/population/problem, I: intervention, C: comparison/control—O: outcome) framework to determine inclusion criteria [ 11 ]. Accordingly, we selected patients undergoing spinal anesthesia as our population, spinal anesthesia as intervention and super-refractory status epilepticus cases as the outcome. Out of the remaining 12, duplicates were removed, full articles were read and five cases that fulfill the definition of super-refractory status epilepticus attributed to a spinal anesthesia drug were identified. They were our references 2,3,5 and 6. The snowballing of those led to identification of our reference1. First and third authors independently did this process and obtained the same results.

The flowchart of the process is shown in Fig.  1 .

The flowchart of systematic literature review process

In cases of reference1 and 6 the duration of seizures was not clearly mentioned, but their authors state that seizures continued despite the administering of anesthetic drugs. Super-refractory status epilepticus is primarily defined by failure to respond to appropriate treatment, not by seizure duration [ 12 ]. Hence, we included those two cases. The case of reference 7 has seizures for a few hours; hence we did not include that. Nonetheless, it is the first report (1994) of a status epilepticus (refractory status epilepticus) case following spinal anesthesia we found [ 7 ]. That patient had a history of seizures and tertracaine was used for anesthesia.

Earlier, we did a nonsystematic literature survey employing various strings. Among results for the string “local anesthetic systemic toxicity” AND “case reports” we have identified our reference 4. Key findings from past six reports of super-refractory status epilepticus attributable to spinal anesthesia are summarized in Table  1 . The authors of some of those papers do not classify their cases as super-refractory status epilepticus cases.

Relationship of the presented case with the existing literature

Similar to our case, all six cases were anesthetized using heavy bupivacaine. Only < 15 mg of bupivacaine was administered to all of them. However, sufentanil was added to heavy bupivacaine in two cases unlike us. None of them or our patient had any history of past seizures. Interestingly, 5/6 patients were women. Three past cases like our patient, had seizures minutes after spinal anesthesia while undergoing cesarean sections. One of them had a history of preeclampsia unlike our case. 3/6 had discomfort in the perineum or coccyx region before seizures and our patient complained of a discomfort that she could not describe. Like in our case, 3/6 had myoclonus or tremors prior to seizures. All past cases survived. None of the past cases had the combination of rhabdomyolysis, a brief cardiac arrest followed by stress cardiomyopathy and central hyperthermia.

There are several other reports of seizures associated with spinal anesthesia [ 3 , 13 , 14 , 15 ]. Only two cases of seizures following spinal anesthesia was reported between 1945 and 1962 according to one author [ 13 ]. Reports have become more frequent lately (Table  1 ). A recent paper summarized 30 publications describing 31 patients and two cats who had had GTCS or myoclonus following spinal anesthesia [ 15 ]. Out of those cases, 64% resolved spontaneously and promptly and in 71% of cases neurotoxicity manifested 30 min after spinal anesthesia, in contrast to our case [ 15 ]. In the literature, there is a spectrum of cases varying from mild self-limiting myoclonus probably originating at the spinal cord level, to super-refractory status epilepticus cases like our case. We think the likely explanation for our case as follows. Initially, she would have had spinal myoclonus which was momentarily controlled by Midazolam. Although its density was higher than that of the CSF (as explained later), a minute fraction of administered ZUPIVAC H would have gradually reached the brain due to movement of cerebrospinal fluid and diffusion [ 16 ]. Then the drug acting on the brain would have initiated GTCS.

Circumstantial evidence for and against suspecting heavy bupivacaine (ZUPIVAC H) as the cause of her seizures

Our hospital uses about 400–450 ampoules of heavy bupivacaine per month at present. No similar incident happened at our hospital during the past 23 years to our knowledge. ZUPIVAC H brand arrived at our hospital for the first time, 45 days before this incident. Ampoules of batch No. DP2203 arrived at our hospital eight days before this incident. Another patient in our hospital developed refractory status epilepticus to ZUPIVAC H three days apart, arousing suspicion of something unique to ZUPIVAC H contributing to these events. Moreover, our patient had undergone spinal anesthesia with heavy bupivacaine (without adjuvants) five years before for her first LSCS, without complications. Therefore, we suspect that the impurity in the drug also contributed to her seizures. Nevertheless, there are reports of patients who had undergone uneventful spinal anesthesia, developing neurotoxicity during subsequent spinal anesthesia [ 15 , 17 ]. Forty five patients in our hospital and more patients in other hospitals have undergone spinal anesthesia with ZUPIVAC H of the same batch without a problem on the same day and within the previous seven days. That fact is against suspecting a factor unique to ZUPIVAC H causing this event. Considering all this, we believe that ZUPIVAC H was the likely reason for her side effects and certain patient factors would have made our patient and the other patient of our hospital susceptible to the side effects of ZUPIVAC H.

Explanation of the patient’s clinical and autopsy findings

Rapid onset of high fever, marked temperature fluctuations ending in death usually occur in central hyperthermia [ 18 ]. We think she had central hyperthermia owing to brain damage due to super-refractory status epilepticus plus possibly due to ZUPIVAC H [ 19 , 20 , 21 ]. Heat generated in muscles during seizures would have contributed to her fever initially, but when her temperature was highest (day 4) there were no seizures. High fever notwithstanding antipyretics and antibiotics, decline in CRP level from day 2 to day 4, normal CSF analysis results and negative central venous catheter blood and urine culture results indicate that infection is unlikely to be the cause of her hyperpyrexia. However, her neutrophil count was very high on day1 but gradually dropped. Her high neutrophil counts can be attributed to status epilepticus [ 20 ].

Neurocardiogenic pulmonary edema following status epilepticus is well documented [ 20 , 21 ]. That explains her first day CXR changes. Our patient had a cardiac arrest on day 2 and resuscitated and on day 4 undergone a prolonged (> 1 h) cardiopulmonary resuscitation (CPR) before her death was confirmed. Respiratory tract infections (pneumonia) is the most common infection associated with status epilepticus [ 20 ].Those would have contributed to the changes in lungs observed at autopsy [ 20 , 21 , 22 ].

Rhabdomyolysis following status epilepticus is common and well known [ 20 , 21 ]. Some drugs given to her like phenytoin and levetiracetam and pre-existing hypothyroidism may have aggravated rhabdomyolysis [ 23 , 24 ].

Sudden unexpected cardiac arrest and death can happen in uncontrolled epilepsy [ 25 ]. Her cardiac arrest on day 2 may be attributable to status epilepticus [ 25 ]. The combination of effects of infused thiopentone and any bupivacaine cardiotoxicity also may have contributed to this. Although the echocardiogram did not depict characteristic left ventricular apical akinesia and ballooning, considering ST elevations in her ECG that appeared after doing the echocardiogram, very high troponin I levels and no blocks in coronaries observed at autopsy we think she may have had Takotsubo cardiomyopathy (stress cardiomyopathy) later. The stress of severe illness, first cardiac arrest and being on three inotropes also would have contributed to this. About 50 Takotsubo cardiomyopathy cases have been reported related to seizure activity, including 15 associated with status epilepticus [ 26 ]. Interestingly, there are reports of ischemic ECG changes, elevated troponin I with normal coronary angiography without seizures resulting after spinal anesthesia described as bupivacaine induced cardiac toxicity by reporting authors [ 27 , 28 ].

Histopathological changes in her kidneys and liver are likely to be due to hypoxemia during prolonged resuscitation after the second cardiac arrest. Liver dysfunctions occur in 25% of patients with rhabdomyolysis by various mechanisms including the released proteases causing liver inflammation [ 29 ]. This explains her high liver enzyme levels. Drugs like levetiracetam also might have contributed to kidney injury [ 30 ]. Her proteinuria is likely to be due to myoglobinuria.

A CSF analysis depicting chemical meningitis was reported in a past patient who had seizures following spinal anesthesia [ 31 ]. Nevertheless, our case and some similar cases did not show CSF evidence of chemical meningitis [ 1 , 2 , 3 , 5 ].

As explained above, her rhabdomyolysis, central hyperthermia, cardiomyopathy and postmortem changes observed in her lungs, kidneys and liver may be largely due to her super refractory status epilepticus with contributions from other factors. Her status epilepticus was due to ZUPIVAC H. That initiated the train of events leading directly to her death. Hence, the side effect of ZUPIVAC H most probably was her underlying cause of death [ 32 ]. However, we do not have adequate information to specifically identify the responsible component(s) of ZUPIVAC H.

Differential diagnoses we considered at different stages

We initially suspected a high spinal or local anesthetic systemic toxicity (LAST). In a patient with short stature and obesity, a high spinal can occur with a regular dose of heavy bupivacaine. The presence of a clear sensory level with preserved handgrip, the absence of any bloody tap, administering only 12.5 mg of bupivacaine, absence of other symptoms of LAST and no initial cardiac involvement indicated that those two possibilities are unlikely. At the end of the day1 and thereafter an adverse reaction to ZUPIVAC H, amniotic fluid embolism, normotensive eclampsia and previously undiagnosed brain pathology were the differential diagnoses. Amniotic fluid embolism is unlikely as at the onset there was no hypoxia with severe respiratory symptoms or cardiovascular collapse. Myoclonus is not the first sign of amniotic fluid embolism. Laboratory tests did not show significant coagulopathy. Later histopathology of the lungs also did not show evidence of amniotic fluid embolism [ 33 ]. Normotensive eclampsia is unlikely because there were no prior proteinuria, excess edema, or prodromal symptoms and onset of super-refractory status epilepticus after the delivery that did not respond to vigorous treatment [ 34 ]. Normal NCCT brain and later autopsy findings excluded previously undiagnosed brain pathology. Malignant hyperthermia (in addition to seizures) after giving suxamethonium is another possibility. However, reduction of ETCO 2 to 34-40mmHg range after admission to the ICU, fever spikes appearing on the following day (after the decrease of ETCO 2 ) and peaking on day 4 were against this possibility. Meningoencephalitis (infection) was also suspected as a reason for the high fever. The CSF analysis and autopsy findings excluded that possibility. At the end of both institutional death reviews, the final consensus was that this was an idiosyncratic reaction to ZUPIVAC H. After the extensive literature review by the first author, considering all available information, we now believe that this is most probably a case of direct local on-target type (mechanism-based) neurotoxicity on the CNS. As explained later, this can be categorized as an idiosyncratic reaction to ZUPIVAC H as well.

Discussion of central nervous system toxicity by bupivacaine and possible mechanisms of toxicity

The International Union of Basic and Clinical Pharmacology (IUPHAR) defines an adverse drug reaction (ADR) as an unwanted or harmful reaction experienced following the administration of a drug or combination of drugs under normal conditions of use and is suspected to be related to the drug [ 35 ]. Accordingly, this is an ADR. IUPHAR defines a side-effect as any effect caused by a drug other than the intended therapeutic effect [ 35 ]. The cesarean section was performed up to the delivery of the baby under spinal anesthesia induced by this drug alone (therapeutic effect was there). Additionally, there was this fatal side effect [ 35 ]. The United States Food and Drug Administration (FDA) use the terms adverse reactions and side effects as synonyms [ 36 ]. The IUPHAR defines drug toxicity as adverse effects of a drug that occur because the dose or plasma concentration has risen above the therapeutic range, either unintentionally or intentionally [ 35 ]. Accordingly, this is very unlikely to be drug toxicity due to the following reasons. She was given a therapeutic dose that has been in use worldwide for a long time [ 37 ]. Spinal anesthesia was working well during the onset of the seizures indicating that a certain percentage of drug molecules were bound to spinal cord receptors. Normally, the peak plasma concentration increase is approximately 0.4 mg/l (0.4 µg/ml) for every 100 mg of bupivacaine injected intrathecally and that peak takes about 50 min to occur [ 38 ]. Considering that there was no bloody tap, the maximum plasma concentration that possibly would have been achieved in 10–15 min after injection was very much lower than 2–3 µg/ml toxic threshold [ 38 , 39 ]. Some authors of past similar case reports considered their cases as LAST [ 3 , 4 ]. Nevertheless, LAST is a term to be used if plasma concentration exceeds the therapeutic range [ 4 , 39 , 40 , 41 , 42 ]. Anesthesiology trainees in Sri Lanka and elsewhere learn > 2 mg/kg as the toxic dose of bupivacaine unless it accidentally gets injected intravascularly [ 40 , 42 ]. Our patient was administered a far lower dose. Hence, LAST may not be an appropriate categorization for cases like this. Local neurotoxicity by local anesthetics is mentioned by a few past authors [ 41 , 43 ]. We think our case and similar cases following spinal anesthesia are more likely to be due to a category of direct local on-target type (mechanism-based) neurotoxicity on the CNS [ 44 ]. This category of toxicity appears to be occurring at unexpectedly low plasma and CSF concentrations, happens very rarely, thus, patient factors may also be playing a role. A case of cardiac toxicity (without seizures) following only 1.1 mg/kg of bupivacaine, injected cutaneously, was reported in a l-carnitine deficient patient [ 45 ]. This is one example of patient factors increasing the risk of bupivacaine toxicity. An experiment demonstrated that administration of supplemental l-carnitine could reverse this risk in rats [ 46 ]. Interestingly, l-carnitine deficiency is associated with seizures, cardiomyopathy, rhabdomyolysis, etc. as well [ 47 , 48 ]. We could not screen her for l-carnitine deficiency.

Toxic reactions usually occurs when the plasma concentration of total (bound and unbound) bupivacaine rise ≥ 2–3 µg/ml (generally ≥ 4 µg/ml) and when the unbound concentration ≥ 0.1–0.2 µg/ml [ 41 , 50 ]. Nonetheless, there is a report of an experiment where a similar aged healthy woman was slowly intravenously infused with bupivacaine and developed GTCS at a plasma concentration of ≥ 1.1 µg/ml [ 49 ]. Cases like ours may have been liable to develop seizures at even lower thresholds due to unidentified factors peculiar to the patient.

Further investigations into future similar cases, for patient factors like l-carnitine and alpha-1-acid glycoprotein deficiency (bupivacaine mostly binds to this protein) etc. would be helpful to clarify the pathophysiology of such events.

Another possible patient factor was either abnormal function or concentration of cell membrane receptors or both. We give an example. In one study, GIRK:Kir3 potassium channels of cell membranes were inhibited within seconds of bupivacaine application [ 50 ]. Other voltage-gated potassium channels are also inhibited by bupivacaine [ 50 ]. Those channels inhibition increase membrane excitability, which can result in seizures [ 50 ]. In one experiment, mice were genetically modified resulting in a lack of similar GIRK2 receptors [ 51 ]. They had spontaneous seizures and were prone to pharmacologically induced seizures as well [ 51 ]. Had her brain GIRK:Kir3 receptors been sparse, inhibition of existing ones by bupivacaine would have contributed to her seizures [ 50 ]. We do not have facilities for further investigation in that line. The impurity appeared to be structurally related to bupivacaine. Thus, it is reasonable to speculate that the impurity might also have inhibited those receptors, perhaps even stronger than bupivacaine. Further studies are necessary to clarify this matter.

Bupivacaine (regular) used for spinal anesthesia comes as a racemic mixture. Had bupivacaine administered to this patient contained more R-(+)-enantiomer, which is more potent that could have been more toxic at a lower dose [ 52 , 53 ]. We could not test ZUPIVAC H for enantiomers.

95% of bupivacaine in plasma is protein bound [ 40 ]. Bupivacaine binds to alpha-1-acid glycoprotein and to a lesser extent to albumin in plasma and in the CSF and unbound bupivacaine is responsible toxic effects [ 40 , 41 ]. If this patient’s CSF had very low levels of above the proteins due to genetic factors, the unbound bupivacaine concentration would have been higher. Serum alpha-1-acid glycoprotein levels decrease during pregnancy and serum levels are correlated with CSF levels [ 52 , 53 ]. This is another patient factor that would have facilitated neurotoxicity. Acidosis decreases protein binding of bupivacaine [ 50 ]. Initial acidosis would have raised unbound bupivacaine in her CSF. We could not test her plasma and CSF for those two proteins. Her preserved handgrip power and finding a sensory level at Th 7 indicate a considerable fraction of the drug injected remained attached to the spinal cord at the initiation of myoclonus/seizures (only a fraction has ascended to brain level). We could not find literature on the safe ceiling of CSF bupivacaine concentration. Future studies on safe CSF ceilings for local anesthetics would be worthy. Our patient never regained consciousness. No significant histopathological changes were seen in her brain. Several such past cases had changes in their EEG and/or MRI and took several days for neurological recovery [ 1 , 2 , 3 , 4 , 5 ]. Those indicate that some damage to brain neurons which are difficult detect in routine histopathology and take long time to recover, has happened in our patient and probably in other similar cases too.

Our patient had an extremely rarely occurring (novel) reaction likely to be due to bupivacaine that is very difficult to explain by the dose and known pharmacology of the drug. Considering the IUPHAR description of idiosyncrasy (type B ADRs) this is an idiosyncratic reaction as well [ 35 ]. Idiosyncratic liver damage due to bupivacaine has been reported [ 54 ]. Therefore, our and similar cases described in references 1–7 and 9 may be categorized as idiosyncrasies to bupivacaine. Nonetheless, Idiosyncratic reactions usually do not occur in a few minutes [ 55 ]. Immune reaction is a known reason behind idiosyncrasy.

This patient underwent uneventful spinal anesthesia for her first LSCS with bupivacaine five years ago. One plausible explanation is that the impurity may have played a role in precipitating seizures. Another possibility is that the patient factor(s) that made her susceptible to status epilepticus would have become clinically relevant in the recent past, even though those may be hereditary factors. For example, l-carnitine deficiency onset at age 39 has been reported [ 56 ].

We believe our analysis of possible patient factors would be helpful to investigators of future such cases to determine the pathophysiology of such seizures /status epilepticus. That will be helpful to improve the management and outcome of such cases.

2.5 ml of 0.5% bupiavacaine without dextrose is also used for spinal anesthesia without problems. As explained above, in this patient anesthesia worked as expected without a high spinal block. According to test results, the density of the batch No.DP2203 samples was 1.026 g/ml (at 20 0 C). Which is much higher than the density of CSF of pregnant women at term (about 1.00030 g/ml) [ 57 ]. Therefore, despite of standard dextrose concentration was not there (as pronounced by NMQAL), only a small fraction of administered bupivacaine would have ascended to her brain level and caused seizures. In one study, CSF bupivacaine concentrations for the same spinal block level differed between patients by sixfold after standardized administration of plain bupivacaine 20 mg [ 58 ]. That underscores the importance of patient factors in shaping CSF bupivacaine concentrations.

Our patient’s CSF bupivacaine concentration (especially unbound bupivacaine concentration) immediately after injection would have been on the higher side due to patient factors. In combination of other patient factors and probably with the impurity it would have caused direct neurotoxicity (seizures). Seizures resulted in other complications and ultimately her death.

Another possible reason for status epilepticus in our patient is the presence of epileptogenic impurities in the bupivacaine ampoule. We would like to give two examples. Pipecolic acid is used in bupivacaine synthesis [ 59 ]. The increase of pipecolic acid and correlated metabolites levels in the brain results in pyridoxine-dependent epilepsy [ 60 , 61 ]. Interestingly, pyridoxine-dependent epilepsy can result in super refractory status epilepticus [ 61 ]. Considering the possibility that some pipecolic acid remained in ZUPIVAC H used for our patient contributing to her seizures, we requested from TGA-Australia to look for that. They did not have facilities to perform relevant tests.

During the process of manufacturing heavy bupivacaine, due to heat, variety of glucose degradation products like 5-Hydroxymethylfurfural could be formed from dextrose [ 62 ]. Some of them have neurotoxic and cytotoxic properties after parenteral administration [ 62 , 63 ]. TGA-Australia, on our request tested for 5-Hydroxymethylfurfural and related substances and their levels in the sample were within the permitted levels as per British Pharmacopeia (BP). TGA-Australia looked for the toxic impurity 2,6-dimethylaniline specified in the BP and Indian Pharmacopoeia, but did not detect this compound in the sample.

Lessons to be learned and the way forward

Ours is a rare and extreme case, and only six similar cases are in the literature. Nonetheless, there are more published milder cases of likely central nervous neurotoxicity occurring after spinal anesthesia [ 15 ]. Published cases are usually the tip of the iceberg. As mentioned in the background, this single case had a big negative impact on the Sri Lankan healthcare system, Sri Lankan society and the reputation of pharmaceutical industry [ 9 ]. All considered, it is crucial to do further studies on the broad subject. Also, it is essential to take actions to prevent recurrences considering existing evidence. We do not know whether the impurity detected in ZUPIVAC H has epileptogenic properties when injected into the CSF. Extraction of the impurity, identification and test injection to laboratory animals CSF may be helpful to determine whether that was responsible for seizures in our patient. Early spinal anesthetic agents have not undergone considerable controlled testing for neurotoxicity according to a review article [ 64 ]. Such studies done according to present standards on spinal anesthetic agents used currently, especially bupivacaine, may throw light on the pathophysiology of similar cases and potential treatments. Previously, we discussed possible mechanisms that can result in cases like ours. We hope that will give a good idea to investigators of future cases where to focus their attention. If an international body takes the initiative to introduce clear consensus definitions to common terms like drug toxicity, LAST and direct neurotoxicity by local anesthetics, that would benefit the medical community. Initiation of a discussion among anesthesiology community to categorize CNS toxicity after subarachnoid injection of local anesthetics as a special category of side effects is worthy. The risk of similar incidents is not mentioned in some manufacturers’ literature. There is no manufacturer’s literature leaflet in the five ampoule packs of ZUPIVAC H. We think the availability of manufacturer’s literature and mentioning the remote risk of such side effects in the manufacturer’s literature of heavy bupivacaine are essential. Although we are from a different country, TGA-Australia kindly analyzed our ZUPIVAC H samples generating information that would be valuable to healthcare community worldwide. It is a good example of the usefulness of international cooperation in investigating such cases. One recent study shows that impurities (contamination) are the commonest cause of defective medicines in Sri Lanka [ 65 ]. Continuous maintenance of a strict quality control process from raw materials to the end product level and adherence to good manufacturing practice protocols by manufacturers can prevent impurities from contaminating bupivacaine. Enhancement of capabilities and effectiveness of the National Medicines Regulatory Authority (NMRA) of Sri Lanka and fully implementation of quality assurance mechanisms always (even during emergency drug procurements and accepting donations of medicines by the Health Ministry) would be useful to ensure the quality, safety and efficacy of bupivacaine at hospitals [ 65 ]. Strengthening post marketing surveillance work on anesthetic drugs by NMRA-Sri Lanka is also worthy. Looking for impurities in heavy bupivacaine in the case of an incident like our case is not in the USP monographs for quality tests. We believe if relevant authorities can consider the inclusion of testing for impurities for quality tests it would be worthy. Administration of 20% fat emulsion to act as an intravenous sink to remove bupivacaine from neurons was one therapy we could have used and that had been used to manage similar cases [ 4 , 40 , 42 ]. 20% fat emulsion was unavailable locally. We suggest to keep at least one bottle of 20% fat emulsion in every operating theater to be used in cases like this. Some readers may think that we could have used propofol to induce and maintain general anesthesia because that contains lipid as well. However, reported cases of seizures due to propofol came to the minds of the team members desperately managing status epilepticus at that time and we used time tested thiopentone (thiopental) [ 66 ]. Propofol was used to manage several similar patients who survived [ 1 , 2 , 3 , 4 , 5 , 14 ]. Thus, we retrospectively think that its benefits might outweigh the risk of aggravated seizures. However, one case treated with thiopentone also survived [ 7 ]. Further studies may clarify this issue. Research to develop an antidote for bupivacaine neurotoxicity with better efficacy would be meritorious. During our literature survey, we noticed that several similar cases (seizures) and several deaths had occurred related to spinal anesthesia by accidental administration of tranexamic acid instead of bupivacaine [ 67 ]. We have excluded that possibility in our case. However, we would like to draw the attention of the anesthesiology community to that issue and reiterate the importance of always adhering to standard safety procedures when administering spinal anesthesia to avoid such medication errors.

Neurotoxicity by bupivacaine (ZUPIVAC H) at spinal cord level would have started myoclonus in this patient. After the drug traveled to the brain, neurotoxicity would have resulted in the super-refractory status epilepticus. Super-refractory status epilepticus would have led to the other complications ending in her death. Patient factors are likely to have made her susceptible to neurotoxicity. There are several such potential factors. The impurity in the drug would also have contributed to her status epilepticus. There are several possible mechanisms that would have led to status epilepticus and her death, which we discussed. Awareness of those mechanisms would be useful to investigators in such future cases. Implementation of our aforementioned suggestions would be helpful to minimize similar future incidents.

Data availability

All relevant data is incorporated in to the manuscript.

Abbreviations

American Society of Anesthesiologists

Central nervous system

Elective lower segment Cesarean section

Intravenous

Generalized tonic clonic seizures

Electrocardiogram

Chest X ray

Intensivecare unit

Nasogastric (tube)

Non-contrast CT scan

Cerebrospinal fluid

Electroencephalogram

International normalized ratio

Magnetic resonance imaging

Cardiopulmonary resuscitation

United States Pharmacopeia

National Medicines Quality Assurance Laboratory

Therapeutic Goods Administration

C-reactive protein

International Union of Basic and Clinical Pharmacology

Adverse drug reaction

Food and Drug Administration

Local anesthetic systemic toxicity

Indian pharmacopoeia

British pharmacopeia

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Acknowledgements

Authors sincerely thank all doctors and all other healthcare workers who contributed to manage this patient, conducted postmortem and histopathology work, death review and analysis of drug samples. We thank all who helped us to publish this article. Special thanks to Amanda Kalachoff and her team of the Therapeutic Goods Administration of Australia who analyzed drug samples and the director of our hospital who co-operated in this endeavor.

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NDBE-Conducted institutional death review meeting of this maternal death, literature survey, conceptualization of this study, wrote the original draft and final manuscript. RMDCR- Initial management of patient, review the original draft. HMRPJ–administered spinal anesthesia, initial management of complications, review the original draft. ABA- Late management of the patient, systematic literature survey verification, review the original draft. PSKN- Late management of the patient, review the original draft. All authors read and approved the final manuscript.

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Ehelepola, N.D., Ranathunga, R.M., Abeysundara, A.B. et al. Super-refractory status epilepticus, rhabdomyolysis, central hyperthermia and cardiomyopathy attributable to spinal anesthesia: a case report and review of literature. BMC Anesthesiol 24 , 132 (2024). https://doi.org/10.1186/s12871-024-02485-x

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Received : 21 December 2023

Accepted : 07 March 2024

Published : 06 April 2024

DOI : https://doi.org/10.1186/s12871-024-02485-x

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• Bupivacaine
• Spinal anesthesia
• Status epilepticus
• Rhabdomyolysis
• Hyperthermia
• Idiosyncrasy
• Cardiomyopathy
• Side effect
• Case report

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ORIGINAL RESEARCH article

Clinical analysis of lupus miliaris disseminatus faciei: a cross-sectional study and literature review provisionally accepted.

• 1 The Second Affiliated Hospital of Xi'an Jiaotong University, China

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The clinical similarity of lupus miliaris disseminatus faciei (LMDF) and other papular granulomatous facial disorders often makes its correct diagnosis challenging. Diagnosis often requires the assistance of pathological examination, and dermoscopy can be used as an auxiliary and non-invasive examination method, however, the current findings remain incomplete. Objectives: This study aimed to summarize the clinical, histopathological and dermoscopic features of LMDF in the Chinese Han population and aiming to provide practical significance to correct diagnosis.. Methods: 109 patients of LMDF were collected in the Department of Dermatology, the Second Affiliated Hospital of Xi'an Jiaotong University from August 2015 to August 2023. Clinical and histopathological manifestation, as well as 44 cases of dermoscopic image features, including background, follicular findings, vessels, and other structures, were summarized and evaluated. The clinical and histopathological manifestations of all patients, as well as the dermoscopic image features of 44 cases, including background, follicular findings, vessels, and other structures, were summarized and evaluated.The most significant histopathological features of LMDF in 109 cases is epithelioid granulomatous infiltrate in the superficial dermis, with or without caseation.The most significant dermoscopic features of LMDF in all 44 cases were orange structureless background (30/44), follicular plug (32/44), follicular white scar-like area (32/44), unspecific linear vessels (24/44), linear vessels with branch (24/44) and white streaks (18/44).Conclusions: Histopathologically, LMDF is characterized by the presence of epithelioid granulomatous infiltrate in the superficial dermis, with or without caseation.Dermoscopically, it exhibits a distinctive orange structureless background, follicular plug, follicular white scar-like area, nonspecific linear vessels, linear vessels with branches, and white streaks.

Keywords: lupus miliaris disseminates faciei, Clinical analysis, histopathology, Image feature, Dermoscopy

Received: 05 Feb 2024; Accepted: 09 Apr 2024.

Copyright: © 2024 Wang, Li and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Shuang Wang, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710049, Shaanxi Province, China

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