Module 2: Refining Your Search - Beyond Automatic Term Mapping

How Do I See and Document What PubMed Is Searching?


MeSH Database


The MeSH Database is the NLM controlled vocabulary thesaurus.

MeSH Database home page screen shot

MeSH terms are organized into a hierarchy, with broader and narrower terms. If your search maps to any MeSH terms, PubMed will automatically explode them to include narrower terms in the MeSH hierarchy. You can view narrower terms in the MeSH Database, which can be accessed from any PubMed page from the menu at the bottom.

Menu bar at the bottom of PubMed page showing NCBI Literature resources with the MeSH link highlighted

In the MeSH hierarchy, Emergency Service, Hospital includes the narrower term Trauma Centers. Both of these terms would be included in your search for emergency room.

Emergency room is an entry term for Emergency Service, Hospital, which is why Emergency Service, Hospital and its narrower terms are included. This is what the hierarchy for Emergency Service, Hospital looks like in the MeSH Database:

Showing the MeSH hierarchy for the term emergency service, hospital with trauma centers underneath

All narrower terms will be included in your search. If your term is located in the MeSH hierarchy in multiple places, narrower terms from each place will be included. Additionally, some narrower terms might have their own narrower terms, and those will be included too.

For example, the term scar automatically maps to Cicatrix.

Screenshot of MeSH Database search results from scar with Cicatrix highlighted at the top of the results

In the MeSH Database, Cicatrix is in the MeSH hierarchy in three places with five narrower terms. One of its narrower terms, Keloid, includes its own narrower term, Acne Keloid, which is also included in your search for scar.

To document your explosions, copy all of the narrower terms from each branch listed.

Cicatrix MeSH heirarchy showing Keloid and Acne Keloid underneath term

If you see a plus sign (+) beside a term in the hierarchy, then you should check to see if that term has additional narrower terms that will be included in your search.

For example, the hierarchy in the MeSH record for Femoral Fractures lists five narrower terms, and one of those, Femoral Neck Fractures, has a plus sign (+) beside it.

Cicatrix MeSH heirarchy showing Keloid and Acne Keloid underneath term

If you view Femoral Neck Fractures in MeSH, you’ll see it has one additional narrower term, Proximal Femoral Fractures, that would be included in your search for Femoral Fractures.

Cicatrix MeSH heirarchy showing Keloid and Acne Keloid underneath term