MeSH terms are used to catalog and index the article records in PubMed. They are arranged into tree structures and are updated every year to include new developments.
Although MeSH terms can be used in PubMed searches, they are found in their own database. This database is similar to searching PubMed but keep in mind that:
To search MeSH, click on MeSH Database under Explore on near the bottom of the PubMed main page.
The National Library of Medicine has produced a short video on MeSH which can be viewed here: https://www.nlm.nih.gov/bsd/disted/video/index.html.
A record could merely contain the keywords you search for but not actually be about that subject.
Let's say that you wanted to research pulmonary cancer and cigarette smoking. Articles sometimes contain wording like this:
"Most research on lung cancer has examined connections with cigarette smoking. In this article we examined pulmonary cancer and chewing tobacco."
These sentences contain terms relevant to our search, but the article is about something entirely different.
MeSH terms are applied to articles after someone from the National Library of Medicine has actually read the article. By labeling an article with MeSH terms, they are telling you what the article is about.
It is also important to search the MeSH terms in order to capture relevant articles that do not use the keywords you have entered.
When searching MeSH, keep in mind:
If you would like to perform a search for all citations with this subject heading, click Add to search builder in the top right area of the screen. The MeSH term will appear in the search builder box. Click Search PubMed to run the search using that term.
At the bottom of a MeSH page is the category tree. You can see where the term you are viewing is placed in the hierarchy and whether it might be more efficient to select a term above or below it in the tree. Terms closer to the top of the tree are broader while those at the bottom of the tree are more focused.
When you search using a MeSH term, PubMed will automatically search for the term you specific, but it will also search for the subcategories beneath that term as well. This is called "exploding" the subject heading.
If you do not want to search the subcategories, click the box next to "Do not include MeSH terms found below this term in the MeSH hierarchy" before you add the term to the builder.
A plus sign (+) is used to signify that there are more subcategories beneath a term that are not currently visible. These deeper categories can be viewed by clicking on the subject heading with the plus sign and then reviewing the category tree area there.
There are 2 downsides to searching with MeSH terms. Both of them are related to time.
For these reasons it is important that you search using keywords and MeSH terms!