Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.


What are Subject Headings?

Ovid MEDLINE uses a system called mapping to suggest the most relevant subject headings to the words typed into the box. Your search does not automatically default to searching by subject term, and is not an option when searching Ovid Journals.

Why use subject headings?

​Similar to MeSH in PubMed, Ovid's Subject Headings are a way to fine-tune your results.  For example, a general search on the word "culture" has the following results:

  • NOT using subject headings will return items about both social culture and urine culture.   
  • WITH the "map to subject headings" box checked brings you to a page that allows you to clarify your search (see below).

Explode and Focus

If you search using the "Map to Subject Headings" option, you might see something that looks like this.  

  • Select the Explode box if you wish to retrieve results using the selected term and all of its more specific terms.
  • Select the Focus box if you wish to limit your search to those documents in which your subject heading is considered the major point of the article.
  • If you want more information about what concepts are included in a given term, click on the information icon.

If your search did not map to a desirable subject heading, select the box "Search as Keyword."
If you select more than one term, you can combine them using a boolean operator (AND or OR).  Remember, if you want articles about one concept OR another, choose OR. 


For example, a search on the word Diabetes using "Map to Subject Headings"  gave these options:

If your topic is Gestational Diabetes, using Subject Headings will save a lot of time by eliminating quite a few other areas.

Clicking on the box in front of Diabetes, Gestational brings you to a page with subheadings.  This allows you to refine your search even further.  If you want all information about Gestational Diabetes, click the Include All Subheadings box.  That will return 7527 results.

Choosing Explode (as shown in the image slightly farther up the page) brings you to the same screen as directly above, except now there are 9017 results.  This is because Explode returns articles that pertain to Gestational Diabetes but do not have it as a main topic.

Choosing Focus (as shown in the image slightly farther up the page) brings you to the same screen as directly above, except now there are 6190 results.  This is because Focus returns only those articles that have Gestational Diabetes as a main topic.

Maps and Directions