Verification Bias2, also termed Workup bias, occurs when a study selectively includes patients for disease verification (or exclusion)  by gold standard testing, based on positive or negative results of preliminary testing, or the study test itself.  To avoid this, a study should include consecutive patients at risk for a particular disease, and not only a subset who underwent definitive testing.

The following excerpt from Bandolier: provides an example
 

.....examples... One was of a new DNA diagnostic test to detect the beast cancer gene administered to biopsy positive breast cancer and to cancer free controls. Since biopsy may be ordered preferentially in women with a family history of breast cancer, the group of "cases" will be enriched by a clinical factor which itself may be associated with the new DNA test.