Searching for trial reports in databases may not retrieve all relevant available studies. Reports may either be missing from the database or may not have been indexed adequately due to lack of detail in titles and abstracts. Some reports are only ever published as abstracts in conference proceedings.

Handsearching is the task of searching through medical journals or conference publications for reports of controlled trials which are not indexed in the major electronic databases like MEDLINE and Embase. For complete identification of reports of trials, electronic searching may need to be supplemented by conducting page by page searches of a variety of sources including journals and supplements, conference proceedings and abstracts, and correspondence.