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Syphilis tests detect
antibodies to the bacterium that causes
syphilis (Treponema pallidum)
in blood, body fluid, or tissue. If an initial screening test shows signs of syphilis, another test is done to confirm a syphilis infection.
Syphilis is a
sexually transmitted infection (STI) that is usually
spread through vaginal, anal, or oral sex.
Tests used to screen for syphilis include:
Tests used to diagnose syphilis include:
A syphilis infection can spread through the bloodstream to all
parts of the body. If not treated, syphilis can cause severe heart disease,
brain damage, spinal cord damage, blindness, and death.
A test for syphilis is done to:
syphilis and other sexually transmitted infections (STIs) is often done for
people who engage in
sexual behaviors that put them at risk. If you have syphilis, your
sex partner or partners should be notified, tested, and treated to prevent
serious complications and to stop the spread of the disease.
Tell your doctor if you:
If you have syphilis, do not have sex until
the test results show you are no longer infected or until you and your sex
partner or partners have completed treatment and the infection has been cured.
Your sex partners should be tested as well.
If you think you might have syphilis, do not
have sex until testing shows that you are not infected.
Talk to your doctor about any concerns you have
regarding the need for the test, its risks, how it will be done, or what the
results may mean. To help you understand the importance of this test, fill
medical test information formmedical test information form(What is a PDF document?).
A syphilis test may be done on a sample of blood, sore, skin, or
spinal fluid, depending on which type of test is done.
The health professional taking a sample of your blood
A sample of fluid or tissue may be taken from an open sore
(chancre) or from a rash that might be caused by syphilis.
Fluid from a sore
that may be caused by syphilis sometimes is collected and examined with a
special type of microscope (darkfield microscope).
A spinal tap (lumbar puncture) is done to collect a
spinal fluid sample for syphilis testing.
For a lumbar puncture, a thin needle is inserted into the spinal
canal in the lower back area. After the needle is in place, a small amount of
cerebrospinal fluid (CSF) is removed from the spinal canal. To learn more, see the topic
The blood sample is taken from a vein in your arm. An elastic
band is wrapped around your upper arm. It may feel tight. You may feel nothing
at all from the needle, or you may feel a quick sting or pinch.
You may have some discomfort when fluid is collected from an open
sore (chancre). But chancres usually are not very tender or painful.
You may have some discomfort during a lumbar puncture to collect
spinal fluid for syphilis testing. To learn more, see the topic
There is very little chance of a problem from having a blood sample
taken from a vein.
There is very little risk of complications from having a sample
taken from an open sore (chancre), skin rash, or mucous membrane.
There is little risk linked with having a lumbar puncture to
obtain a spinal fluid sample for syphilis testing. To learn more, see
Syphilis tests detect
antibodies in blood or body fluid or tissue to the
bacterium that causes syphilis (Treponema pallidum).
Results are usually available in 7 to 10 days.
No syphilis bacteria are seen.
Syphilis bacteria are seen.
No antibodies to syphilis are present. This is called a
nonreactive or negative result.
Antibodies to syphilis bacteria are present. This is called a
reactive or positive test.
A result that is not clearly normal or abnormal is called
inconclusive or equivocal.
The antibody to the syphilis bacteria (reagin) is not
present. This is called a nonreactive or negative result.
The antibody reagin is present. This is called a reactive or
The accuracy of testing often depends on the
stage of syphilis. Syphilis testing may need to be repeated if initial results
are uncertain or if you have had repeated exposure to syphilis, such as from
repeated unprotected intercourse.
Reasons you may not be able to have the test or why the results may
not be helpful include:
Most states require doctors to report all cases of
syphilis to the local health department. In some states, doctors
are also required to ask for the names and addresses of your recent sex
partners. If you have syphilis, the health department may contact you to make sure
that you get treatment. If you give the names of your sex partners to your
doctor or the health department, they will be contacted in confidence by the
health department and advised to have a test for syphilis.
Centers for Disease Control and Prevention (2010). Syphilis section of Sexually transmitted diseases treatment guidelines, 2010. MMWR, 59(RR-12): 26–39. Also available online: http://www.cdc.gov/std/treatment/2010/default.htm.
U.S. Preventive Services Task Force (2009). Screening for syphilis infection in pregnancy: U.S. Preventive Services Task Force reaffirmation recommendation statement. Annals of Internal Medicine, 150(10): 705–709.
Other Works Consulted
Chernecky CC, Berger BJ (2013). Laboratory Tests and Diagnostic Procedures, 6th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Current as of:
June 4, 2014
Kathleen Romito, MD - Family Medicine & Kirtly Jones, MD - Obstetrics and Gynecology
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