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VDRL test
Venereal disease research laboratory test
The VDRL test is a screening test for syphilis. It measures substances (proteins), called antibodies, that your body may produce if you have come in contact with the bacteria that cause syphilis.
How the Test is Performed
The test is most often done using a blood sample. It can also be done using a sample of spinal fluid. This article discusses the blood test.
A blood sample is needed.
Blood sample
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.
How the Test will Feel
When the needle is inserted to draw blood, some people may feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
This test is used to screen for syphilis . The bacteria that cause syphilis is called Treponema pallidum.
Syphilis
Syphilis is a bacterial infection that is most often spread through sexual contact.
Your health care provider may order this test if you have signs and symptoms of a sexually transmitted illness (STI).
Syphilis screening is a routine part of prenatal care during pregnancy. Several states also require screening for syphilis prior to obtaining a marriage license.
This test is similar to the newer rapid plasma reagin ( RPR ) test.
RPR
RPR (rapid plasma reagin) is a screening test for syphilis. It looks for antibodies that are present in the blood of people who may have the disease...
Normal Results
A negative test is normal. It means that no antibodies to syphilis have been seen in your blood sample.
The screening test is most likely to be positive in the secondary and latent stages of syphilis. This test may give a false-negative result during early- and late-stage syphilis. This test must be confirmed with another blood test to make the diagnosis of syphilis.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
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.
FTA-ABS
The FTA-ABS test is a blood test to detect antibodies to the bacteria Treponema pallidum, which causes syphilis.
The VDRL 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.
Some conditions may cause a false-positive test, including:
- HIV
- Lyme disease
- Certain types of pneumonia
- Malaria
- Systemic lupus erythematosus
The body does not always produce antibodies specifically in response to the syphilis bacteria, so this test is not always accurate.
Risks
Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
References
LaSala PR, Smith MB. Spirochete infections. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods . 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 59.
Radolf JD, Tramont EC, Salazar JC. Syphilis ( Treponema pallidum ). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases . 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 239.
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Blood test - illustration
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
Blood test
illustration
-
Blood test - illustration
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.
Blood test
illustration
Review Date: 9/10/2015
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
