What is Automatic Explosion?
MeSH is organized into a tree or hierarchy structure which moves from least specific to most specific.
Explosion refers to the automatic process where PubMed will search for all the more specific terms listed underneath a given MeSH term as well.
For example, as we can see below, the MeSH term Myocardial Infarction has several more specific terms underneath it in the hierarchy, such as Anterior Wall Myocardial Infarction, Inferior Wall Myocardial Infarction, and Shock, Cardiogenic. If a person searches with the MeSH term Myocardial Infarction, all of these more specific MeSH terms will also be searched automatically due to Automatic Explosion.
Tip: Automatic Explosion only searches for these more specific terms within the MeSH Field. In other words, it looks for articles which have had these MeSH terms applied to describe them. However, the system does not search for these terms in the titles and abstracts. If you would like them to be searched in these fields, you would want to add them to your search strategy as additional keyword synonyms.
How can I turn Explosion off if I don't want to use it?
If you do not want a particular term to be exploded, you can turn this feature off by tagging the term with the field tag [mesh:noexp].
Alternatively, if you put your term into quotation marks, add a truncation symbol, or apply a different field tag (such as [tw]), all of these tools will also turn off both the Automatic Term Mapping and Automatic Explosion processes.
