The Full form of VDRL is Venereal Disease Research Laboratory. VDRL is a blood test for syphilis that detects an antibody that is present in the bloodstream when a patient has syphilis. This test is used to detect if a person has been infected with the bacteria causing syphilis, which is a sexually transmitted disease. This test is only indicative, and if positive, it must be followed up with another blood test to make a definitive diagnosis of syphilis. The test is performed if a person shows signs and symptoms of sexually transmitted illness. It is a routine test performed during pregnancy to check if there is a possibility of you suffering from syphilis. The possible symptoms may include a small painless sore, swelling in the lymph nodes near the sore and skin rash that does not cause itching. There is no specific condition as to when this test should be avoided. No special preparation is needed. A blood sample is taken. The test is not always accurate as the body may not always produce antibodies upon exposure to the bacteria causing syphilis. The test is less sensitive during the early and late stages of the disease.