1. Define the topic: know what you are looking for. Take the time to write down your topic and consider it from all angles. Try to be specific about what it is you want to discover about your topic. It helps to write it out in the form of a question. Ex: What is the best method to screen pregnant women for streptococcal infections?

  2. Break it down into its individual concepts. Are you looking at a disease/condition? Do you want to know diagnosis / therapy / outcome / prognosis / risk factors, etc? Is there a particular age group / ethnic group / gender? Do you want to know adverse effects / prevention & control / mortality / etiology? Ex: pregnant / women / screening / streptococcal infections.

  3. Decide on the words/phrases to describe the concepts. Consider all possible words or phrases that might be used to describe the concepts of your topic. These should include synonyms, variations in spelling (US vs. UK), word endings (singular, plural), variant terminology (electrocardiograms, electrocardiography), and related terms (cataract extraction, intraocular lens implantation). Ex: pregnant/pregnancy – screening/testing – women/woman/female.

  4. Search for each concept as a separate set and use subject headings. Creating separate sets for each part of your topic allows you to combine and recombine results to modify your strategy as your search. Use subject headings (called Medical Subject Headings or MeSH in Medline) to capture concepts rather than specific keywords. For example, the MeSH heading “neoplasm” in Medline returns articles that include the keywords neoplasm(s), tumor(s), and cancer(s).

  5. Combine your sets. Define the relationship between individual sets. Use the Boolean operators AND, OR and NOT. “ANDing” two sets together returns citations that contain both set concepts. “ORing” two sets returns citations that contain either one or both set concepts. Using “NOT” will retrieve citations that contain one set concept, but not the other.

  6. Display your results. Take a look at your search results. Are any of the articles right on target? Did you get too many? Too few? Nowhere near your topic at all? Try checking the subject headings in the “closest fit” article.

  7. Refine your search, if necessary. Try steps 1-5 over again. You may need to either broaden your search concepts or narrow them. Example: staphylococcus aureus becomes staphylococcus infections (and vice versa).




Focus - The “focus”(*) function indicates that the MeSH term you have selected is one of the primary focuses of the article. This is especially important to use when your MeSH heading otherwise retrieves a very large number of citations.

   Focusing a search in Ovid Medline


Subheadings - When you use “subheadings” you can narrow down your search concept to a specific aspect of that topic. If you are only interested in that specific aspect(s), consider using those aspects.The default for subheadings is to use ALL of the subheadings.

Using subheadings in Ovid Medline


Limit(s) - You can refine your search by “limiting.” Common limits are language, age groups, gender, publications types, year ranges and human.

Limiting in Ovid Medline


Truncation - Sometimes you will need to search using keywords/textwords if a MeSH heading does not exist. Keywords may have variant endings, (including singular and plural) all of which may be relevant to your topic. Truncating ($) allows you to search a root keyword with various endings. (Ex. For “dental floss”, the truncation also picked up flossed/flossers/flosses, etc.) Use this with care, as truncating can retrieve irrelevant information (electr$ will get electricity, electronic, electrocardiography, etc.).

Using truncation in Ovid Medline


Wildcards - Wildcards (# or ?) help when there are variant spellings of a term, where the variation occurs within the term itself.

Example: wom#n =
woman OR women.
Example: orthop?edic = orthopedic OR orthopaedic

Using wildcards in Ovid Medline