Objective: To determine the effect of the use of abbreviations and acronyms on citation retrieval in MEDLINE searches.
Methods: Twenty common medical abbreviations that retrieved a minimum of 400 citations each in MEDLINE text word searches were studied. Each abbreviation was entered in a MEDLINE subject search to determine whether it mapped to an appropriate medical subject heading (MeSH) term. The MeSH category and the number of citations retrieved were recorded. The abbreviation and its definition were each entered in separate text word searches, and the number of citations retrieved was recorded. Sets were combined to determine the number of identical and unique citations retrieved in the searches.
Results: MEDLINE recognized all 20 abbreviations and mapped them to appropriate MeSH headings. MeSH term assignment, however, may be case- and space-sensitive. MeSH term searches retrieved more citations than text word searches for 18 of 20 abbreviations. Comparison of the document sets yielded by each search method revealed a subset of citations common to each. Although all sets retrieved showed overlap, no two were identical. In addition, each citation set contained a proportion of unique documents.
Conclusion: Retrieval of all unique citations required three searches; subject with abbreviation, text word with abbreviation, and text word with definition. These results have important implications for MEDLINE users.