What is a MeSH Search — and why should you care about it since text word searching is usually so successful?
A MeSH search retrieves subjects, not words: When you search with a MeSH term, you restrict your search to MEDLINE citations indexed with that subject heading.
It's true that PubMed's basic search is fast, easy and often very successful. Automatic Term Mapping usually identifies the appropriate MeSH terms associated with your search concepts.
However, restricting your search to selected medical subject headings (MeSH) can provide much needed focus and precision.
In this module, we'll review when it may be best to do a MeSH Search, and we'll go over using the MeSH Database as a tool to build a MeSH search and launch it in PubMed.
You need more precise results in a subject search. For example:
1. Your basic search results are too large and not focused on your main concepts.
In a basic search, your search terms (and the synonyms found by Automatic Term Mapping) will be found in all the fields of a record, including ones where your search term only mentioned in the abstract. A MeSH search is a type of field search, and like any search using field qualifiers, it will retrieve fewer results than a similar text word search. More importantly, in a MeSH search, PubMed restricts your results to articles indexed with a subject heading for your topic.
2. A large amount of literature has been published on your topic.
A MeSH search enables you to restrict your search to Major Topic Headings only. This allows you to retrieve articles where your topic is a major point discussed, rather than a secondary focus or finding.
3. You need to disambiguate a search word or phrase.
Use the MeSH database to find MeSH terms, including Subheadings, Publication Types, Supplementary Concepts and Pharmacological Actions, and then build a PubMed search.
Step 1: Locate and Select MeSH terms from the MeSH Database
An easy way to access the MeSH Database is by using the link on the PubMed home page, under More Resources. Open the drop-down menu near the PubMed query box and select MeSH (see screenshot, right). Or, start a search of the MeSH Database from a PubMed search page.
Then search for your concept. Your results will be a list of MeSH terms, with brief definitions. The results are displayed in a summary display format in relevance-ranked order. Select (click on) the one that looks most accurate to display the MeSH Full Record. (Note: If only one match is found, the Full Record will be displayed automatically.)
Step 2: Review the MeSH record Full Display.
The definition and list of subheadings for the MeSH term appear in the MeSH full display to help ensure that you have chosen the correct term. This display also assists you in identifying alternative search terms. Scroll down to see:
Entry terms: the search terms that, when entered in the MeSH database, will "map" to the current MeSH term.
MeSH Tree: The MeSH tree hierarchy is especially helpful if you are not familiar with your topic - it allows you to view the term in a variety of contexts. Also, make sure you are searching at the right level in the tree. If not, select a broader or narrower term.
Step 3: Use the MeSH record full display to further refine your search. There are three options:
Step 4: Launch the Search in PubMed.
Click the Add to search builder button to send your MeSH term and subheading to the PubMed Search Builder (find it on the upper right side of the MeSH full record screen).
Note: The MeSH search box is still available: you could continue to add MeSH terms to the search statement if you wished.
Finally, click the Search PubMed button to send the search to PubMed
Your topic is a new or emerging concept for which a MeSH term does not yet exist.
You suspect that very little has been published on your topic - meaning, again, there is probably no MeSH term.
Your topic is a gene, unless it is a very heavily studied gene such as BRCA1 (most genes do not have MeSH terms).
You want to retrieve recently published articles. The newest articles in PubMed may not yet be indexed for MEDLINE. There is a short lag time (a few days to many weeks) between when citations enter the PubMed database and when they are described with MeSH terms.
An article you need is not indexed for MEDLINE. PubMed includes over 1.5 million articles that are not indexed with MeSH for MEDLINE.
A basic subject search is the best way to retrieve articles in the situations described above.
Examples of When MeSH Does & Doesn't Help
|
Type of Search |
Topic |
Explanation |
| One aspect of a larger topic | Transplantation of adult stem cells | A basic text word search retrieves over 25,000 hits. A MeSH search with subheadings quickly provides focus. |
| Rare topic | "Baby rattle" pelvis dysplasia | A basic text word search is best for rare topics. There is no MeSH term for baby rattle pelvis dysplasia. |
| New topic | Virophage | A basic text word search is also best for new topics. There is no MeSH term for virophage. |
| Complicated topic | Metabolism of methicillin by resistant Staphylococcus | A basic search here is too broad. A MeSH search helps focus on the relationship between the terms. |
What is a MeSH Search — and why should you care about it since text word searching is usually so successful?
A MeSH search retrieves subjects, not words: When you search with a MeSH term, you restrict your search to MEDLINE citations indexed with that subject heading.
It's true that PubMed's basic search is fast, easy and often very successful. Automatic Term Mapping usually identifies the appropriate MeSH terms associated with your search concepts.
However, restricting your search to selected medical subject headings (MeSH) can provide much needed focus and precision.
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