Ovid MEDLINE

MEDLINE uses a language called Medical Subject Headings (MeSH) to index the articles in the database. MeSH terms provide a way to search all articles on a topic by using one phrase to describe a particular topic. For example, the MeSH term "lung neoplasms" is used for searching all of the following: lung cancer, pulmonary cancer, pulmonary neoplasms, cancer of the lung. It is easier to use the one MeSH term than to try to think of all the possibilities for lung cancer.

If the term mapping works effectively, you don't need to know the exact MeSH term. Entering a variant term such as "lung cancer" should pull up its MeSH equivalent. However, there will be occasions where the mapping doesn't work as expected or there is no MeSH equivalent. There is always the option to search for a term as a keyword in the title, abstract, and MeSH terms.

• Be sure to use the Advanced Search tab (this is the default search for Northwestern University's version of Ovid).

• Enter a single topic on the Enter keyword or phrase line.

• Be sure that Map Term to Subject Heading is checked (usually checked by default).

• Click Search.

• Click on the MeSH term to see where it fits in the MeSH tree, a hierarchical list of terms. The MeSH tree shows you the context of the heading in relation to broader and more specific headings to help you narrow down your topic. Terms in the tree go from more general (left) to more specific (right).

• Click on the  icon to see a definition of the MeSH term.

• Check the Explode box to retrieve citations using the selected term and all of its more specific terms (those that are indented below the main term).

• Check the Focus box to limit your search to those documents in which your subject heading is considered to be the major point of the article.

• Check the box or boxes you want to include in your search and click  at the top of the screen. On the next page, you can choose Subheadings.

Click the box in front of Include All Subheadings if you want all articles on your topic. If you want to limit your search to particular aspects of a topic, select the appropriate subheadings.

• Repeat the search process above for all of your search terms.
• To combine search statements, check the terms you'd like to combine and click Combine selections with 'And' or 'OR'. Alternatively, you can type the set numbers separated with 'AND' or 'Or', e.g. 1 and 2 - this will retrieve articles containing both the results from sets 1 and 2.