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Module 4: Literature Search Strategy

Advanced Search

Subject heading searching is a standardized set of words or phases utilized in specific databases. It is another method of searching that will  yield results that are relevant to your topic

  • Also known as "controlled vocabulary"
  • Used by a database to describe concepts in the literature collected by that database
  • Consistent in their definition across all records in the database
  • Less flexible than keywords -- you need to know the proper term to use
What to Look For

To search for subject headings for your topic, check to see if the database features an online thesaurus that you can use to browse for subject that match your topic:

  • PubMed has MeSH -- see below to learn more about MeSH
  • CINAHL has CINAHL Subject Headings
  • PsycInfo has APA Thesaurus of Psychological Index Terms

Alternatively you can try:

  • Starting with a keyword search
  • Browsing the results -- select a handful of results that seem relevant
  • Looking at the section for Subject Headings, also commonly labeled "Subjects"
  • Taking note of any relevant terms
  • Redoing your search with the new terms

What is MeSH?

Also known as Medical Subject Headings, MeSH is the U.S National Library of Medicine's (NLM) controlled vocabulary used to index journals in MEDLINE/PubMed. These terms provide a consistent way to find articles that have utilize different terminology for the same concepts. MeSH is assigned to each article by subject analysts when applicable. It typically can take anywhere from 3 to 6 months for MeSH terms to be applied to an article, creating a delay.

Check out this tutorial from the National Library of Medicine to learn more about MeSH: https://www.nlm.nih.gov/bsd/disted/meshtutorial/introduction/index.html

How to use Medical Subject Headings (MeSH) in PubMed

The MeSH Database is accessible directly from PubMed's homepage. In the MeSH database, you can:

  • Locate and select MeSH terms 
  • View definitions, scope, and relationships of a given MeSH term
  • Select subheadings to build a more specific search

In the next tab, I will outline how to search for MeSH terms in PubMed. For an alternative experience, please check out this video from NCBI that walks you through using the MeSH database. Note: this video was made prior to the update of PubMed. Although PubMed looks different now, the MeSH database has not changed. 

Medical Subject Headings (MeSH) in PubMed

Step 1: Locate and Search for Terms in the MeSH Database

The easiest way to access the MeSH database is by using the link on PubMed's homepage, located right under the Explore icon.

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Search for one term at a time. Although the MeSH database is extensive, it is important to note that not every term is going to have a corresponding MeSH term.

Results will be displayed with brief definitions, ranked by relevance. Select the entry that best fits your needs to view the full record page. If there is only one result available, you will be brought directly into the record

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Step 2: Review the MeSH Record

At the top of the MeSH recored page, you will see the term's definition and a list of subheadings. Scroll down to view Entry Terms (if available) and the MeSH Hierarchy.

  • Entry Terms: terms that, when used to search in the MeSH database, will "map" to the current MeSH term
  • MeSH Hierarchy: displays a hierarchy tree and where your term falls within it. The MeSH Hierarchy is very helpful for those who may not be familiar with their topic. The hierarchy shows the term in a variety of contexts

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Step 3: Refine your Search with the MeSH Record

There are three possible options for refining your search with the MeSH record:

  • Apply one or more subheadings: Adding subheadings to a MeSH term allows you to focus your search to those specific topics. If you do not apply any subheadings, PubMed will include all of them when it searches for your MeSH term
  • Restrict to MeSH Major Topic: This will retrieve only citations where your subject is one of the main topics featured in an article
  • Choosing the option "Do not include MeSH terms found below this term in the MeSH hierarchy: Only do this if you do not want PubMed to search for the narrower terms that appear beneath your MeSH term in the MeSH hierarchy
Step 4: Search for your MeSH Terms in PubMed

When you are ready, click the "Add to Search Builder" button located right under the PubMed Search Builder box, found on the right side of the screen. If you are using any subheadings, be sure to check their boxes  prior to select "Add to Search Builder". 
If you are ready to search for your MeSH term in PubMed, select the Search PubMed.

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Keywords vs Subject Headings

Keywords Subject Headings
Natural language used to describe your topic Pre-defined vocabulary used to describe the content of an item such as an article in a database
Flexible in how you search -- terms can be combined together in multiple ways Limited flexibility in how you search -- the term must match the pre-defined vocabulary 
Database will look for the terms anywhere in the record  Database looks for terms only in the subject heading or description field 
May yield too many or too few results Used to focus on one or a select number of aspects of a broader subject 
Can yield many irrelevant results, especially if you are using broaden or commonly used terms Results are typically very relevant to the topic -- exclusive use can create too specific of a query

Adapted from https://libguides.mit.edu/c.php?g=175963&p=1160804