Subject headings

Examples of how to search directly for subject headings (if known) in the search box.

MeSH in MEDLINE (Ovid): Headings are presented in a hierarchical structure from broader to narrower. Below demonstrates where the subject heading "Health Education" fits within the MeSH structure. A plus symbol next to a heading indicates that there are more narrow headings below that heading.

Term Finder in MEDLINE: Another way to explore MeSH in MEDLINE is via the Term Finder. This short video from Wolters Kluwer explains the basics of using this feature. (Video length - 4 min 0 sec)

Emtree in Embase or Emcare (Ovid): Headings are not presented in a hierarchical structure. Can only see one level above and below the heading searched for.

Business Thesaurus in Business Source Ultimate (EBSCOhost): Headings are not presented in a hierarchical structure. Can only see one level above and below the heading searched for. Must click on narrower terms to see headings further below as no indication given when further terms exist e.g. no [ + ], [NT].

Choosing to 'explode' a subject heading finds sources associated with the heading and all the narrower headings below it in the hierarchical structure of the relevant thesaurus¹. This will expand your results to include sources about the broader topic and the narrower headings.

¹Not in SPORTDiscus and Business Source Ultimate - only first level of narrower headings are searched.

When to use: Sometimes sources are indexed to specific or narrow terms, so by choosing a broad subject heading, you may not find every document that is relevant to your topic. If you have checked where a subject heading sits within the thesaurus and most or all of the narrower headings are relevant, consider exploding that subject heading. 

Limitations: May return results that are not relevant to your topic. Only explode a subject heading if most or all of the narrower headings are relevant.

Example: Explode in MEDLINE (Ovid) using 'Map Term to Subject Heading': Search for your heading with the 'Map Term to Subject Heading' box ticked. On the following page, select the box left of the heading (1) and the 'Explode' box (2), then 'Continue' (3). 'Continue' again to select all subheadings and then the exploded subject heading will appear in the search history. The same format applies in other databases that use the Ovid interface e.g. APA PsycInfo, Embase and Emcare.

Example: Explode in MEDLINE (Ovid) - Direct search: Search directly for an exploded heading in the search box by entering 'exp' before the heading, and with a forward slash ( / ) preceding the heading. The same format applies in other databases that use the Ovid interface e.g. APA PsycInfo, Embase, and Emcare.

Format examples of exploded subject headings in specific databases as they appear in the search history.

Choosing to 'focus' as subject heading finds only documents in which the subject heading is considered the major topic. This will narrow your results and return highly specific sources.

When to use: If your topic has a large body of existing literature, focusing a subject heading can help narrow results to only those that discuss the topic in depth.

Limitations: Can limit the number of results in a search. If you get too few results, run the search again without focusing the heading.

Example: Focus in MEDLINE (Ovid) using 'Map Term to Subject Heading': Search for you heading with the 'Map Term to Subject Heading' box ticked. On the following page, tick the box left of the heading (1) and the 'Focus' box (2), and then 'Continue' (3). 'Continue' again to select all subheadings and then the focused subject heading will appear in search history. The same format applies in other databases that use the Ovid interface e.g. APA PsycInfo, Embase, and Emcare.

Example: Focus in MEDLINE (Ovid) - Direct search: Search directly for a focused heading in the search box by entering an asterisk ( * ) before the heading, and with a forward slash ( / ) preceding the heading. The same format applies in other databases that use the Ovid interface e.g. APA PsycINFO, Embase and Emcare.

Format examples of focused subject headings in specific databases as they appear in the search history.

No option to focus subject headings in Business Source Ultimate, SPORTDiscus. 

Qualifiers, also called subheadings, can be used in combination with subject headings to restrict the focus of your search to a particular aspect of a subject. This can improve the precision of your search.

Databases with qualifiers: CINAHL Complete, Cochrane Library, Embase, Emcare, MEDLINE

Databases without qualifiers: If you have incorporated qualifiers in your master search, you will need to remove or substitute them in the following databases: APA PsycInfo, Business Source Ultimate, ERIC, SPORTDiscus

When to use: To narrow in on a particular concept within a subject heading. For example, a MEDLINE search for 'Health Education/td' will return results that specifically include trends in health education and not other aspects of education.

Limitations: Can limit the number of results in a search. If you get too few results, you can run the search again with more or all of the qualifiers selected.

Other considerations:

Not all qualifiers can be used in conjunction with all subject headings.

Not all qualifiers were introduced into all databases at the same time.

Example: Using qualifiers in MEDLINE (Ovid) using 'Map Term to Subject Heading': Search for your heading with the 'Map Term to Subject Heading' box ticked. On the following page, tick the box left of the heading, and then 'Continue'.

The next page presents the available qualifiers for the subject heading you have chosen. 

1. Clicking 'Continue' or 'Include All Subheadings' searches the subject heading with all qualifiers. 
2. Tick the checkbox next to individual qualifiers to search the subject heading with one or more qualifiers.
3. Click the information icon next to a qualifier to see its definition and year of entry.

Once you have made your selection(s), click continue. The subject heading with qualifier(s) will appear in the search history. The same format applies in other databases that use the Ovid interface e.g. Embase.

Example: Using qualifiers in MEDLINE (Ovid) - Direct search: Search directly for a subject heading with qualifier(s) applied in the search box by entering the two-letter qualifier code after the term and forward slash. You can find the qualifier codes in the MeSH Qualifiers List (linked above).

Format examples of subject headings with a qualifier applied in specific databases as they appear in the search history.

In some databases, qualifiers can be searched on their own (without a subject heading). These are known as floating subject headings.

Databases with floating subject headings: CINAHL, Cochrane Library, Embase, Emcare, MEDLINE

Databases without floating subject headings: If you have incorporated floating subject headings in your master search, you will need to remove or substitute them in the following databases: APA PsycInfo, Business Source Ultimate, ERIC, SPORTDiscus

When to use: When there is a particular element you are interested in that is best represented by a qualifier rather than a subject heading. For example, you may be interested in finding standards across multiple disciplines. 'Standards' is a qualifier in MEDLINE and CINAHL and can be searched as a floating subject heading. This will return results where the qualifier 'Standards' has been applied to any subject heading.

Limitations: Brings in results where the qualifier is attached to any subject heading where the pairing is possible. If this brings in lots of irrelevant sources, try combining the floating subject heading with keywords. e.g. st.fs. AND (patient educat*).

You can also use a floating subject heading search to help find additional subject headings. 

It is best practice to search using both keywords and subject headings. In databases with thesauri, some records may not have headings, or be poorly indexed.

Example: MEDLINE (Ovid) - searching using both subject headings and keywords (subject headings are denoted by a forward slash / )

For more information about keyword searching, visit the Keywords page of this guide.