1: What happens when I search PubMed with a phrase?
How PubMed Processes a Phrase
PubMed treats phrases in basically the same way as single terms. When you search in PubMed for a phrase, three things happen:
Mapping to MeSH
First, PubMed’s Automatic Term Mapping (ATM) feature attempts to map the phrase to an appropriate MeSH term.
For example, failure to thrive maps to:
"failure to thrive"[MeSH Terms]
Terms in All Fields
PubMed also splits the phrase into individual terms, combined with AND, in all fields.
For failure to thrive, this looks like:
("failure"[All Fields] AND "thrive"[All Fields])
Phrase in All Fields
Finally, PubMed searches for the terms as a phrase in all fields.
For failure to thrive, this is:
"failure to thrive"[All Fields]
PubMed also includes other terms in your search, such as American/British spellings, and the plural/singular version of terms. If the term maps to a MeSH heading that has narrower terms in the MeSH hierarchy, those narrower terms will be included in the search but do not appear in the Search Details.
A glance at the search results confirms that this search returns results relevant to the topic of failure to thrive.
Key Takeaway
When you search PubMed with a phrase, PubMed’s Automatic Term Mapping (ATM) feature will attempt to map the phrase to MeSH.