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NURS 3351: Nursing Research and Informatics

Subject Searching

Subject searching is a more precise way to search, particularly when your search term can have more than one meaning. Every item in a database is assigned specific subject headings using a controlled vocabulary, which can vary by database. Most medical databases use MeSH (Medical Subject Headings), which is continually updated by the National Library of Medicine. MeSH uses a hierarchical system that allows for easy broadening or narrowing of topics. CINAHL uses subject headings unique to the database that use the same structure. 

  • More specific than keyword searching
  • May be too specific
  • Varies by database
It's best to use both keyword and subject searching when doing a comprehensive search!


Using Boolean operators can improve your search by broadening or narrowing it.


Refer to this document for reminders about how Boolean works.

Subject Searching in MEDLINE and CINAHL

Start by selecting any desired limiters. Next enter your search term. It's best to start with only one search term using this method. Check the box next to "Suggest search terms,"  then click search.

medline search box with suggest subject terms checked

Next you can choose the heading or headings that match your topic. Once you select the heading, you can also choose to Explode, mark it as a Major Concept, or select additional Subheadings to include in your search.

Explode: More results

Broadens your search; results will contain any of the narrower subject terms. See the terms that would be included by clicking on the term and looking at the tree view.

partial tree view of pain mesh term

Partial tree view of the term "Pain"

Major Concept: Fewer results

Narrows your search by limiting your results to only articles that include that subject heading as a main subject.

major concept detail of medline search

Subheadings: Limit your search to one or more facets, such as diagnosis, therapy, or ethics. Subheadings will vary.

detail of mesh subheading in medline

To add additional subject headings to your search, go to the bottom of the page and click "Browse Additional Terms." Select the heading that matches your topic, etc.

browse additional terms

Be careful to select the correct operator for joining your search terms. Selecting AND will search for all terms listed. Selecting OR will bring back results that may include only one of your terms.

combining search terms

Research Log

To help keep track of searches conducted, use the research log.