Skip to Main Content

Health Sciences Literature Searching: Refining Subject Heading Searches

A guide to help you search the Health Sciences literature

Jump to:

Use the following links to jump to a chosen topic to refine your subject headings search:


Term Trees

Major Concept




Subheadings narrow the use of a controlled vocabulary term by specifying the topics included in a search. Explode increases the number of results by including all of the subheadings in your search. Major Concept limits the number of results by selecting articles that list a particular subheading as its main topic.


The box we clicked to select Pregnancy in Adolesence as a controlled vocabulary term also shows its subheadings.

Subheadings are the different fields that apply to your search. "Include All Subheadings" places no restrictions on your search and retrieves articles from all of the fields listed.

Clicking a box next to a subheading limits the search to articles in that field. In our search, "Economics" is included but "Classification" and "Drug Effects" are not.

Click on the green "Search Database" button when you have selected your subheading(s).


If you are unsure which subheadings to include, click on the yellow speech bubble next to one.

 The pop-up (its Scope) gives you extra information to help you with your decision.


A term tree lists subject headings and subheadings that are related to each other. Broader terms contain narrower terms.

Term trees

If you want to see a layered list, or “hierarchy tree”, of your subject heading, click its name.

This shows subject headings and subheadings for topics that are broader or narrower than the one you chose. If a term is specific, then it retrieves fewer articles. If it is broad, it retrieves more articles.

For example, "Pregnancy in Adolescence" is narrower than "Maternal Age" but broader than "Maternal Age 14 and Under."


If you decide to research a broader topic, such as pregnancy at different ages instead of just teenage pregnancy,  click the box next to "Maternal Age". That new subject heading includes articles for "Maternal Age 14 and Under", "Maternal Age 35 and Over", and "Pregnancy in Adolescence".

If you decide to narrow your search by, for example, specializing in pregnant preteens instead of all pregnant teenagers, click the box next to "Maternal Age 14 and under." That will become your new subject heading, excluding ages above 14 in "Pregnancy in Adolescence" and "Maternal Age 35 and Over".

Clicking more than one box includes both subject headings in your search.

It presents you with the choice of using the search operators AND and OR with the terms you selected. To eliminate one of the terms, click the red box with the X next to it.

Click the green "Search Database" button when you are done selecting terms from the tree.


Using the Main Concept choice helps you to focus on a chosen subject heading, thereby limiting your search further.

Major Concept

By checking the major concept box next to certain subject heading, CINAHL will only show you articles in which the selected subject heading is a major concept. So, for this search, CINAHL will only give us articles that have "pregnancy in adolescence" as a major concept instead of articles that just include "pregnancy in adolescence," limiting our search further.


Scope reveals extra information about a subject heading or subheading and lists terms for related topics.


"Scope" lists additional topics and subject headings or subheadings related to your chosen term. It is on the far right.

Clicking the yellow speech bubble pops up extra information about a term. It lists related terms and other topics to consider for inclusion.

Scope is also used to learn why a subheading is used.

Finish the search by closing the window and clicking the green "Search Database" button.


Using explode will help you broaden your subject heading search if you've narrowed it too much.


Have you refined your search too much and have too few resources? You can use the following explode feature to search amongst more subheadings under a main subject heading.


Clicking the box beneath Explode includes all of the subject headings in a term tree, expanding your search. This will include all subheadings underneath the chosen heading, so that you won't have to select each subheading individually.


Subject Guide

Profile Photo
David Nolfi


If you're confused about using CINAHL, look for icons that are shaped like question marks or thought bubbles for more information.

You can also Ask A Librarian any time of day for help.