What Is the Purpose of a Scoping Review?

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-27

Quick Answer

• A scoping review maps the existing evidence on a broad topic to clarify key concepts, identify knowledge gaps, and inform whether a full systematic review is warranted.
• The practical next step is to select a reporting guideline from the EQUATOR Network before drafting your protocol, ensuring transparent and complete methodology.
• A key limitation is that scoping reviews do not assess the quality or risk of bias of included studies, so they cannot answer questions about intervention effectiveness.

Understanding the Purpose of a Scoping Review

A scoping review is a structured approach to examining the breadth of literature on a given topic. Unlike a systematic review that seeks to answer a specific clinical or policy question through rigorous synthesis, a scoping review aims to map the existing evidence, clarify definitions, and identify gaps where research is lacking. Researchers in life sciences, agriculture, and veterinary medicine increasingly use scoping reviews to understand what is known before committing to expensive primary research or a full systematic review.

The distinction matters for practical decisions. If you are a laboratory manager deciding whether to invest in a new diagnostic protocol, a scoping review can tell you what evidence exists, where it was produced, and what methods were used. It will not tell you whether the protocol works better than alternatives. That question requires a systematic review with quality appraisal and meta-analysis.

Scoping reviews follow a transparent, reproducible methodology. The most widely recognized framework involves identifying the research question, searching relevant databases, selecting studies against explicit criteria, charting the data, and collating results. This structure distinguishes a scoping review from a traditional narrative literature review, which may be selective and lack explicit methods.

Five Key Purposes of Scoping Reviews

Mapping the Extent and Nature of Evidence

The primary purpose of a scoping review is to map the volume, characteristics, and distribution of research on a topic. This mapping answers questions such as: How many studies exist? What study designs were used? In which geographic regions was research conducted? Which populations or species were studied?

For example, a researcher investigating antimicrobial resistance in dairy cattle might use a scoping review to determine whether studies have focused on mastitis pathogens, calf diarrhea, or respiratory disease. The map reveals also what has been studied but also the methods used, such as cross-sectional surveys versus longitudinal cohort studies. This information helps researchers avoid duplicating existing work and identify where new primary research is needed.

The mapping function also serves funding decisions. Grant reviewers at agencies such as the National Institutes of Health expect applicants to demonstrate awareness of the existing evidence landscape. A scoping review provides the transparent, reproducible foundation for that demonstration, showing that the applicant has systematically examined what is known instead of relying on a selective reading of the literature.

Identifying Gaps in the Literature

A second core purpose is identifying gaps where evidence is absent, insufficient, or contradictory. Gaps can take several forms: populations that have not been studied, outcomes that have not been measured, settings that have been ignored, or methodological weaknesses that limit confidence in findings.

Consider a scoping review on biosecurity practices in poultry operations. The review might reveal that most studies focus on commercial layer flocks while backyard flocks remain understudied. This gap matters for extension agents and veterinarians who need evidence-based guidance for small-scale producers. The scoping review provides the documentation needed to justify new research in that underserved area.

Gap identification also supports research prioritization. When multiple gaps exist, the scoping review can help stakeholders decide which gaps matter most based on the volume of related evidence, the severity of the problem, and the feasibility of new research. This prioritization is a practical output that goes beyond simple description.

Clarifying Key Concepts and Definitions

Scoping reviews frequently address topics where terminology is inconsistent or contested. The review process reveals how different authors define the same concept, which can be a barrier to synthesis and communication.

Take the concept of "animal welfare" as an example. Some studies define welfare in terms of biological functioning, others emphasize affective states, and still others focus on natural living. A scoping review can chart these definitions across the literature, showing how the concept has evolved and where disagreements persist. This clarification helps researchers select definitions for their own work and helps practitioners understand what different studies actually measured.

Conceptual clarification is especially valuable in emerging fields where terminology has not stabilized. Precision livestock farming, one health, and sustainable intensification are all areas where scoping reviews have helped map how key terms are used. This mapping supports clearer communication across disciplines and improves the quality of subsequent research questions.

Examining How Research Is Conducted

A fourth purpose is examining the methods used in existing studies. This includes study designs, data collection approaches, analytical techniques, and reporting practices. Understanding methodological patterns helps researchers design studies that build on strengths and address weaknesses in the existing literature.

For example, a scoping review of studies on heat stress in feedlot cattle might reveal that most research uses controlled environmental chambers instead of natural field conditions. This finding has practical implications. Producers need to know whether laboratory findings translate to real-world feedlot settings, and researchers need to design field studies that complement the existing experimental work.

Methodological examination also supports reporting quality. The EQUATOR Network provides access to reporting guidelines that help researchers write transparent, complete methods sections. A scoping review that identifies poor reporting in a field can point to the need for better adherence to these guidelines, improving the overall quality of future research.

Informing Whether a Systematic Review Is Feasible

A fifth purpose is determining whether a full systematic review is feasible and warranted. Systematic reviews require a focused question, a sufficient body of comparable studies, and adequate reporting quality. Scoping reviews provide the preliminary evidence needed to make this determination.

If a scoping review finds that studies are too heterogeneous in design, outcomes, or populations, a systematic review may not be feasible. If the evidence base is too sparse, a systematic review would produce an empty or inconclusive synthesis. In these cases, the scoping review itself becomes the final product, documenting what exists and what is missing.

This feasibility function saves time and resources. Systematic reviews are labor-intensive and require specialized skills. Conducting a scoping review first prevents wasted effort on a synthesis that cannot answer the intended question. It also provides the justification needed when a systematic review is not appropriate.

Scoping Review Versus Other Review Types

Scoping Review Versus Systematic Review

The most common confusion is between scoping and systematic reviews. Both use systematic search methods and transparent reporting, but they answer different questions. A systematic review addresses a specific, focused question about the effects of an intervention or the accuracy of a diagnostic test. It includes quality appraisal and often meta-analysis to produce a quantitative summary.

A scoping review addresses broader questions about the nature and extent of evidence. It does not assess quality or risk of bias, and it does not produce a quantitative synthesis. The output is a map of the evidence, not a summary of effects.

The choice between the two depends on the question. If you need to know whether a specific intervention reduces disease incidence, a systematic review is appropriate. If you need to know what interventions have been studied, in which populations, and with what outcomes, a scoping review is the better choice.

Scoping Review Versus Narrative Literature Review

A narrative literature review is a traditional approach where the author selects and discusses studies without explicit, reproducible methods. This approach is efficient for introducing a topic or providing a personal perspective, but it is vulnerable to selection bias. The reader cannot verify that the author considered all relevant evidence.

A scoping review uses explicit methods that can be replicated by others. The search strategy, inclusion criteria, and data charting process are documented in detail. This transparency is a major advantage for researchers who need to demonstrate that their understanding of the evidence is complete and unbiased.

For students and early-career researchers, the scoping review offers a structured introduction to evidence synthesis methods. The explicit methodology provides a framework for learning while producing a useful product. Many graduate programs now accept scoping reviews as thesis projects because they teach transferable skills in searching, screening, and data extraction.

Scoping Review Versus Evidence Gap Map

An evidence gap map is a visual presentation of the evidence in a particular field, often using a matrix format with interventions on one axis and outcomes on the other. Scoping reviews and evidence gap maps share the goal of describing the evidence base, but they differ in format and purpose.

A scoping review produces a narrative and tabular description of the evidence. An evidence gap map produces a visual tool that stakeholders can use to identify where evidence exists and where it is missing. Some scoping reviews include gap maps as part of their output, but the two are distinct products.

The choice between them depends on the intended audience and use. If the goal is to inform research prioritization among diverse stakeholders, an evidence gap map may be more accessible. If the goal is to provide a detailed methodological description of the evidence, a scoping review is more appropriate.

At a Glance

Practical Steps for Conducting a Scoping Review

Step 1: Define the Research Question

The research question for a scoping review should be broad enough to capture the range of evidence but focused enough to be searchable. A common framework uses population, concept, and context. For example, a question about biosecurity in livestock production might specify the population as livestock operations, the concept as biosecurity practices, and the context as smallholder systems in low-income countries.

The question should be developed with input from stakeholders who will use the results. This might include farmers, veterinarians, extension agents, or policymakers. Their input ensures that the review addresses questions that matter in practice, beyond questions that interest academics.

Step 2: Select a Reporting Guideline

Before beginning the review, select a reporting guideline from the EQUATOR Network. The EQUATOR Network maintains a comprehensive database of reporting guidelines for different study types, including the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews. Selecting the guideline early ensures that the final report includes all required elements.

The guideline serves as a checklist throughout the review process. It reminds the researcher to document the search strategy, report the number of records screened, explain exclusions, and present results in a structured format. Following the guideline improves the quality and usability of the final product.

Step 3: Develop and Document the Search Strategy

The search strategy is the foundation of a scoping review. It should include multiple databases relevant to the topic, such as PubMed for biomedical research, agricultural databases for farming topics, and regional databases for studies published outside major international journals.

The search strategy should be developed with a librarian or information specialist who has expertise in systematic searching. The strategy should combine controlled vocabulary and free-text terms, and it should be documented in enough detail that another researcher could replicate it. The documentation should include the databases searched, the date of the search, and the exact search strings used.

Step 4: Screen Studies Against Explicit Criteria

Screening involves applying inclusion and exclusion criteria to the records identified by the search. The criteria should be developed from the research question and documented in advance. Common criteria include publication date, language, study design, and relevance to the population and concept of interest.

Screening typically occurs in two stages. The first stage screens titles and abstracts to remove clearly irrelevant records. The second stage screens full texts to confirm eligibility. Both stages should be conducted by at least two reviewers working independently, with disagreements resolved through discussion or a third reviewer.

Step 5: Chart the Data

Data charting is the scoping review equivalent of data extraction in a systematic review. The researcher extracts information from each included study into a standardized form. Common charting fields include author, year, country, study design, population, concept, context, and key findings.

The charting form should be developed and piloted on a small number of studies before full data extraction begins. This piloting process identifies ambiguous fields and allows the form to be refined. The final charting form should be included as an appendix to the review report.

Step 6: Collate, Summarize, and Report Results

The final step is collating the charted data into a meaningful summary. This typically involves a narrative description organized around the research question, supported by tables and figures that display the distribution of studies by year, country, design, and other characteristics.

The results should be reported according to the selected reporting guideline. The report should describe the search results, the screening process, the characteristics of included studies, and the main findings organized by theme. The report should also discuss limitations of the review itself, such as language restrictions or database coverage.

Records and Measurements

Documentation Requirements

Scoping reviews require meticulous documentation at every stage. The search strategy, screening decisions, and charting forms should be preserved in a way that allows external verification. Many researchers use reference management software to track records and systematic review software to manage screening and data extraction.

The documentation serves multiple purposes. It allows the review to be updated when new evidence emerges. It provides the transparency needed for publication in peer-reviewed journals. It also provides a record that can be audited if questions arise about the review's methods or conclusions.

Measuring the Evidence Base

The scoping review produces quantitative descriptions of the evidence base. These include the number of records identified, the number screened, the number included, and the distribution of included studies across countries, years, and designs. These numbers provide a snapshot of the field that can be compared across reviews and over time.

The review also produces qualitative descriptions of the evidence. These include the range of definitions used, the types of outcomes measured, and the gaps identified. These qualitative findings often have more practical value than the quantitative counts because they reveal what is missing and what is poorly understood.

Data Management Considerations

Data management is an integral part of scoping review conduct. The National Institutes of Health Data Management and Sharing Policy describes expectations for managing and sharing data generated by research. While scoping reviews primarily use published literature instead of generating new data, the search records, screening decisions, and charting forms are research outputs that should be managed and shared appropriately.

Researchers should plan for data management before beginning the review. This includes deciding where the data will be stored, how it will be organized, and how it will be shared with other researchers. A data management plan prepared in advance prevents problems later in the review process.

Common Failure Patterns

Inadequate Search Strategy

A common failure is an underdeveloped search strategy that misses relevant studies. This can occur when the search relies on a single database, uses only free-text terms without controlled vocabulary, or fails to include regional databases that index non-English literature. The result is a review that presents an incomplete picture of the evidence.

Prevention requires investment in search development. Working with a librarian, testing the search strategy against known relevant studies, and documenting the strategy in detail all reduce the risk of missing evidence. The search should also be peer-reviewed using established tools for search strategy evaluation.

Unclear Inclusion Criteria

Another failure is inclusion criteria that are too vague to apply consistently. If the criteria do not clearly define the population, concept, and context, different reviewers will make different decisions about which studies to include. This inconsistency undermines the reliability of the review.

Prevention requires developing criteria that are specific enough to be applied mechanically. Each criterion should be defined in operational terms that leave little room for interpretation. The criteria should be piloted on a sample of records, and disagreements between reviewers should be tracked and resolved systematically.

Overly Broad Scope

A scoping review that attempts to cover too much ground can produce a superficial result. If the topic is too broad, the search may identify thousands of records, and the charting may produce a table that is too large to interpret. The review may describe the evidence without providing meaningful insights.

Prevention requires careful scoping of the research question. The population, concept, and context should be defined narrowly enough to produce a manageable body of evidence. If the initial search identifies an unmanageable number of records, the question should be refined before proceeding.

Confusing Scoping and Systematic Reviews

A failure to distinguish scoping and systematic reviews can lead to inappropriate methods and conclusions. If a researcher conducts a scoping review but draws conclusions about intervention effectiveness, the review overreaches its methods. If a researcher conducts a systematic review without a scoping review first, the review may be based on an incomplete understanding of the evidence landscape.

Prevention requires clarity about the purpose of the review from the outset. The research question should determine the review type, not the other way around. Researchers should be explicit about what the review can and cannot conclude based on its methods.

Welfare and Safety Context

Ethical Considerations in Evidence Synthesis

Scoping reviews raise ethical considerations that differ from primary research. The main ethical obligations relate to transparency, accuracy, and avoiding harm through misrepresentation of the evidence. Researchers have a responsibility to report their methods honestly and to avoid overstating what the evidence shows.

The Committee on Publication Ethics Core Practices describe expectations for ethical conduct in research publication. These include honest reporting of methods and results, proper attribution of sources, and disclosure of conflicts of interest. Scoping review authors should follow these practices to maintain the integrity of their work.

Animal Welfare Context

For scoping reviews in animal agriculture, the welfare context is relevant in two ways. First, the review may include studies that involved animals, and the review should note the welfare standards applied in those studies. Second, the review itself may inform welfare policy and practice, so the conclusions should be drawn carefully to avoid unintended consequences.

Researchers conducting scoping reviews on animal topics should be aware of the ethical standards that apply to the primary studies they are reviewing. The review should note whether included studies followed accepted welfare guidelines and should flag studies that raise welfare concerns. This information helps readers assess the reliability and acceptability of the evidence.

Professional Escalation Criteria

Scoping reviews can identify findings that require professional attention. If the review reveals evidence of systematic animal welfare problems, poor reporting practices, or research misconduct, the findings should be escalated to appropriate authorities. This might include institutional animal care committees, journal editors, or regulatory agencies.

Researchers should also escalate when the review reveals gaps that have immediate practical consequences. For example, if the review shows that a common farming practice lacks any evidence base, this finding should be communicated to extension agents and practitioners who can address the gap through education or new research.

Limitations of Scoping Reviews

No Quality Appraisal

The most important limitation is the absence of quality appraisal. Scoping reviews describe what evidence exists but do not assess whether that evidence is trustworthy. A scoping review may include studies with serious methodological flaws, and the reader cannot distinguish these from well-conducted studies.

This limitation means that scoping reviews cannot answer questions about what works. They can only describe what has been studied. Researchers who need to know whether an intervention is effective must conduct a systematic review with quality appraisal and synthesis.

No Quantitative Synthesis

Scoping reviews do not produce quantitative summaries of effects. They cannot calculate pooled effect estimates or confidence intervals. This limits their usefulness for decision-making that requires quantitative answers, such as cost-benefit analysis or risk assessment.

The absence of quantitative synthesis also means that scoping reviews cannot detect small but consistent effects that might be apparent in a meta-analysis. A scoping review might show that many studies have been conducted, but it cannot show what those studies collectively demonstrate.

Time and Resource Requirements

Scoping reviews require substantial time and resources. The search, screening, and charting processes are labor-intensive, and the documentation requirements add to the workload. Researchers who underestimate these requirements may produce incomplete or rushed reviews.

The resource requirements should be considered when deciding whether a scoping review is the right approach. For some questions, a narrative review may be sufficient. For others, a full systematic review may be necessary. The scoping review is most valuable when the evidence landscape is unknown and the goal is to map that landscape before further investment.

Rapidly Changing Evidence

Scoping reviews can become outdated quickly in fields where research is advancing rapidly. The search date is a snapshot in time, and new studies published after the search will not be included. This limitation is shared with systematic reviews, but it is more significant for scoping reviews because they are often used to inform research planning.

Researchers should note the search date prominently in the report and should consider whether an update is needed before the review is used for major decisions. In rapidly moving fields, the review may need to be updated more frequently than in stable fields.

Frequently Asked Questions

What is the main purpose of a scoping review?

The main purpose is to map the existing evidence on a broad topic, including the volume, characteristics, and distribution of research. This mapping clarifies concepts, identifies gaps, and informs whether a systematic review is feasible.

How is a scoping review different from a systematic review?

A scoping review maps the breadth of evidence without assessing quality or producing quantitative synthesis. A systematic review answers a focused question about intervention effects, includes quality appraisal, and often includes meta-analysis.

Do scoping reviews assess the quality of included studies?

No. Scoping reviews do not assess quality or risk of bias. They describe what evidence exists but do not evaluate whether that evidence is trustworthy.

Can a scoping review answer questions about intervention effectiveness?

No. Because scoping reviews do not assess quality or synthesize results quantitatively, they cannot answer questions about what works. Those questions require a systematic review.

What is the role of reporting guidelines in scoping reviews?

Reporting guidelines, available through the EQUATOR Network, provide a checklist of elements that should be included in the final report. Following a guideline improves transparency and completeness.

How long does a scoping review take to complete?

The time required varies with the breadth of the topic and the volume of evidence. A focused scoping review may take several months, while a broad review can take a year or more.

What are the main limitations of scoping reviews?

The main limitations are the absence of quality appraisal, the absence of quantitative synthesis, the time and resource requirements, and the potential for the review to become outdated as new evidence emerges.

When should a researcher choose a scoping review over other review types?

Choose a scoping review when the goal is to map the evidence landscape, clarify concepts, or identify gaps. Choose a systematic review when the goal is to answer a focused question about effects. Choose a narrative review when a quick, non-systematic overview is sufficient.

Using the Evidence

Related Articles

• Scoping Review vs Meta-Analysis: Clarifying Their Distinct Roles in Evidence Synthesis
• Research Assistant Careers in Life Science
• Umbrella Reviews: Synthesizing Evidence from Multiple Meta-Analyses
• Biomedical Science Research Building
• Reproducible Research in R: A Practical Guide for Life Scientists

References and Further Reading

• Research Methods Resources. National Library of Medicine.
• EQUATOR Network. EQUATOR Network.
• Core Practices. Committee on Publication Ethics.
• NIH Grants and Funding. National Institutes of Health.
• ORCID for Researchers. ORCID.
• Data Management and Sharing Policy. National Institutes of Health.
• NCBI Literature Resources. National Center for Biotechnology Information.
• PubMed. National Library of Medicine.

This article is educational and does not replace institutional policy, professional advice, or applicable safety and regulatory requirements.