Syphilis is a bacterial infection that is most often spread through sexual contact.Read Article Now Book Mark Article
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.
The CSF-VDRL test is used to help diagnose neurosyphilis. It looks for substances (proteins) called antibodies, which are sometimes produced by the ...Read Article Now Book Mark Article
A blood sample is needed.
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.
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.
This test is similar to the rapid plasma reagin (RPR) test.
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 provider about the meaning of your specific test results.
What Abnormal Results Mean
A positive test result means you may 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 FTA-ABS test is used to detect antibodies to the bacteria Treponema pallidum, which causes syphilis.Read Article Now Book Mark Article
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:
- Lyme disease
- Certain types of pneumonia
- Systemic lupus erythematosus
The body does not always produce antibodies specifically in response to the syphilis bacteria, so this test is not always accurate.
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood 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
- Multiple punctures to locate veins
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 237.
US Preventive Services Task Force (USPSTF); Bibbins-Domingo K, Grossman DC, et al. Screening for syphilis infection in nonpregnant adults and adolescents: US Preventive Services Task Force recommendation statement. JAMA. 2016; 315(21):2321-2327. PMID: 27272583 pubmed.ncbi.nlm.nih.gov/27272583/.