|
|
VDRLDefinition VDRL is a screening test for syphilis that measures antibodies called reagins that can be produced by Treponema pallidum, the bacteria which causes syphilis. However, the body does not always produce reagin specifically in response to the syphilis bacteria, so the test is not always accurate. The test is similar to the newer reagin plasma response (RPR) test. How the test is performed Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell with blood. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding. In infants or young children: The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any bleeding. How the test will feel When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing. Why the test is performed Syphilis is a highly treatable infection. In addition to screening individuals with signs and symptoms of syphilis or other sexually transmitted diseases, syphilis screening is a routine part of prenatal care during pregnancy. Several states also require screening for syphilis prior to obtaining a marriage license. Normal Values The value of a negative test depends on the stage of syphilis that is suspected. Screening test is most valuable in secondary and latent syphilis as it will most likely be positive during these stages. During primary and tertiary syphilis this test may be falsely negative and additional testing may be needed prior to ruling out syphilis. What abnormal results mean A positive test result may mean you have syphilis. If the test is positive, the next step is to confirm the results with an FTA-ABS test, which is a more specific syphilis test. The VRDL test's ability to detect syphilis depends on the stage of the disease. The test's sensitivity to detect syphilis nears 100% during the middle stages; it is less sensitive during the earlier and later stages. The following conditions may cause a false positive test:
What the risks are Risks associated with venipuncture are slight:
Special considerations This screening test for syphilis is usually performed on blood. If an individual is suspected of having brain involvement with syphilis (neurosyphilis), the VDRL test may be performed on spinal fluid. References U.S. Preventive Services Task Force. Screening for Syphilis Infection: Recommendation Statement. Ann Fam Med 2004; 2: 362-365.Illustrations
Page Content: Venereal Disease Research Laboratory test |
   |
