VDRL - Venereal Disease Research Laboratory. A blood test used to diagnose syphilis. Required in many states prior to marriage. Read as nonreactive or negative if you do not have syphilis. The VDRL can also be positive is cases of leprosy, malaria, mononucleosis, lupus, hepatitis A, and pregnancy. Positive VDRL tests are usually followed up by a more specific test (FTA-ABS).