Nursing

PubMed Search Tips

• Using Search Fields
• Narrowing Searches
• Expanding Searches
• Searching with MeSH
• Finding Systematic Reviews
• Proximity Searching
• Premade Search Strategies

This page will cover a selection of search features of PubMed. For more specific guidance, see PubMed's extensive user guide:

Using Search Fields

PubMed has a wide variety of search fields that you can limit your search to. A search that includes no search fields will default to searching All Fields [all]. The [all] field uses Automatic Term Mapping, which can be helpful to expand a search, but doesn't give you as precise a level of control over the search.

Specifying Search Fields

How do you specify a field to be searched? Just put the field code in brackets after the search term. For example, if you wanted to search for articles with anesthesia in the title:

"anesthesia"[ti]

To avoid accidental automatic mapping, put your search term in quotes. This means that if you have multiple words that you don't want searched as a phrase, each word will have to specify a field:

"anesthesia"[ti] AND "nursing"[ti] instead of "anesthesia nursing"[ti]

You can specify different fields for different terms in the same search. For example, if you wanted to add a search for authors affiliated with Johns Hopkins to the previous search:

"anesthesia"[ti] AND "johns hopkins"[ad]

Select List of PubMed Search Fields

This is only a partial list of some of the more useful fields to search. A full list of search fields is available at the PubMed User Guide.

Narrowing Searches

If you are getting too many results, there are a number of ways to narrow your search:

• Replace a broad concept with a more specific one
  "embolism"[tw] → "pulmonary embolism"[tw]
• Combine your search with another concept using the Boolean operator AND
  "embolism"[tw] → "embolism"[tw] AND "anesthesia"[tw]
• Use one of PubMed's filters to limit by factors such as date, language, or publication type
• Narrow your search to a specific search field. See the section of the page on using search fields.

Expanding Searches

If you are getting too few results, there are a number of ways to expand your search:

• Replace a specific concept with a broader one
  "pulmonary embolism"[tw] → "embolism"[tw]
• Search in all fields and allow PubMed to apply Automatic Term Mapping
  "pulmonary embolism"[tw] → pulmonary embolism
  Automatic Term Mapping explodes pulmonary embolism into the following search:
  "pulmonary embolism"[MeSH Terms] OR ("pulmonary"[All Fields] AND "embolism"[All Fields]) OR "pulmonary embolism"[All Fields]
• Include synonyms for your search concept using the Boolean operator OR
  As can be seen above, Automatic Term Mapping attempts to do some of this for you, but you can control it directly by creating your own search. This is an example of MeSH and keyword synonyms for "pulmonary embolism" (in this case including "pulmonary infarction" as a relevant related concept):
  (“Pulmonary Embolism”[Mesh] OR “Pulmonary Infarction”[Mesh] OR “pulmonary embolism”[tw] OR “pulmonary embolisms”[tw] OR “pulmonary infarct”[tw] OR “pulmonary infarcts”[tw] OR “pulmonary infarction”[tw] OR “pulmonary infarctions”[tw] OR “pulmonary thromboembolism”[tw] OR “pulmonary thromboembolisms”[tw])
  Note that I put the full search in parentheses. This ensures that all the synonyms are grouped together before being combined with any additional search terms you might include in your full search (such as AND "anesthesia"[tw])

Searching with MeSH

MeSH are the controlled vocabulary for MEDLINE, which is a database that is one of the major sources of content for PubMed. MEDLINE is also available at Dugan Library through EBSCO.

Controlled vocabulary (also know as subject headings or subject terms) are standardized terms applied to sources by human indexers or via automated indexing (the National Library of Medicine transitioned to automated indexing for MeSH in 2022).

Comparing MeSH to Keyword Searching

• Precision (how accurate are the results in terms of relevancy): Results found via MeSH are more likely to have high precision than keyword searching. This is because MeSH terms should only be assigned to items that extensively cover that topic, as opposed to keywords that could exist as a passing reference in the record.
• Recall (how complete is the results list compared to the total pool of relevant items): MeSH results are mixed on the issue of recall compared to keyword searching. On the one hand, the fact that MeSH terms use standardized language means that recall can be higher than the use of keywords if that keyword search failed to account for a wide variety of possible synonyms. On the other hand, MeSH headings will fail to recall items that are not subject to MeSH indexing (all those outside of MEDLINE) and might fail to return relevant results that are either incorrectly indexed (the jury is still out on the final quality of automated MeSH indexing for instance) or relevant to the search, but not a primary enough theme of the item to be indexed on under the topic.

For these reasons, the most comprehensive searches will generally use a mix of both MeSH terms and keywords.

Using MeSH

There are a number of ways to make use of MeSH terms:

• MeSH Database: the MeSH Database is linked on the PubMed home screen under the "Explore" Icon.
  • Use the search bar to find relevant MeSH terms.
  • The results page will display the identified term as well as the hierarchy of terms in the tree, any of which can be selected.
  • You can add a term to a PubMed search by using the PubMed Search Builder on the right of the results page.
  • By default, searching for a MeSH term will also search for any terms under it in the hierarchy, but you can choose to conduct the search unexploded.
• Item Records: item records in PubMed that have been indexed with MeSH will have a list of assigned MeSH terms.
  • Scroll down on the record to the section labelled MeSH Terms.
  • Each term will be hyperlinked. Click on a term to perform a search in PubMed for that MeSH term.

Finding Systematic Reviews

PubMed provides a search strategy that you can use to find systematic reviews on your topic. In your search, add the following:

systematic[sb]

This is a shortcut to instruct PubMed to add the following to your search:

For example, if you wanted to search for systematic reviews on pulmonary embolism, a basic search could be:

pulmonary embolism AND systematic[sb]

See other sections of this page for creating more sophisticated searches for concepts like pulmonary embolism.

Proximity Searching

Proximity searching allows you to search for a set of words within a given distance from each other. Searching just for keywords can fail because the words are not connected to each other. Phrase searching (using parentheses) can also fail in cases where the words can be in a variety of orders or cases where additional words may sometime be added within the phrase.

How to Use Proximity Searching in PubMed

Proximity searching is only available in the title [ti] and title/abstract [tiab] fields. The formula is as follows, where the field is either [ti] or [tiab] and n is the number of words that can exist between the search terms:

"search terms"[field:~n]

Proximity Search Examples

"healthcare access"[tiab:~1] finds both "healthcare access" and "access to healthcare."
"healthcare access"[tiab:~2] additionally finds "access to the healthcare system," "access to standardized healthcare," and more, but will also pull in more irrelevant results that happen to have "healthcare" and "access" within two words of each other.

"patient physician relationship"[tiab:~0] finds "patient-physician relationship" and "physician-patient relationship." Using ~0 for proximity means that no additional words can be added between the terms, but the terms can appear in any order.

Premade Search Strategies

PubMed provides documentation on a set of premade search strategies on a variety of topics:

PubMed Special Queries

Most of the listed search strategies can just be copied and pasted into a PubMed search, but PubMed also includes a couple of special search interfaces:

Clinical Queries

• Allows for searching limited according different types of clinical studies.

Health Services Research (HSR) Queries

• Allows for searching limited according to issues of quality and cost of healthcare.