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Syphilis Tests

Test Overview

Syphilis tests are done to check for a syphilis infection. They look for antibodies to the bacteria that cause syphilis. Some tests look for the syphilis bacteria.

Syphilis is a sexually transmitted infection. That means it is spread through sexual contact: vaginal, anal, or oral sex. It can also spread to the fetus of a person who has syphilis during pregnancy.

Testing is done on blood, body fluid, or tissue samples.

If a first screening test shows signs of syphilis, another test is done to confirm a syphilis infection. Your doctor may choose from many tests to screen for and confirm a syphilis infection.

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Why It Is Done

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.

Screening for syphilis and other sexually transmitted infections is often done for people who engage in sexual behaviors that put them at risk. A test for syphilis is done to:

  • Screen for syphilis. Screening tests help your doctor look for a certain disease or condition before any symptoms appear. This increases the chance of finding the infection when it can be cured or treated to avoid long-term problems.
  • Screen for syphilis during pregnancy. Syphilis during pregnancy can cause very serious problems.
  • Confirm that a person has syphilis.
  • Check how well treatment is working.

If you have syphilis, your sex partner(s) should be told, tested, and treated to prevent serious problems and to stop the spread of the infection.

Learn more

How To Prepare

If you think you might have syphilis, do not have sex until testing shows that you are not infected.

If you have syphilis and are being re-tested, do not have sex until the test results show that 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.

How It Is Done

A syphilis test may be done on a sample of blood, sore, skin, or spinal fluid, depending on which type of test is done.

Blood test from a finger stick

For a finger-stick sample, the health professional will puncture the skin on your middle or ring finger with a small instrument called a lancet. Then they'll collect a small amount of blood.

Blood test from a vein

A health professional uses a needle to take a blood sample, usually from the arm.

Sore or skin sample

A sample of fluid or tissue may be taken from an open sore or from a rash that might be caused by syphilis.

Spinal fluid sample

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. After the needle is in place, a small amount of fluid is removed from the spinal canal.

How It Feels

Blood sample

When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.

Sore or skin sample

You may feel some discomfort when fluid is collected from an open sore. But syphilis sores usually aren't very painful.

Spinal fluid sample

You may feel some discomfort during a lumbar puncture to collect spinal fluid.

Risks

Blood sample

There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.

Sore or skin sample

There is very little risk of problems from having a sample taken from an open sore, skin rash, or mucous membrane.

Spinal fluid sample

There is little risk linked with having a lumbar puncture to obtain a spinal fluid sample. Some people develop a headache after having a lumbar puncture. It usually goes away within a week.

Results

Results are usually available in 7 to 10 days.

Syphilis tests

Normal:

Normal results are called negative.

No syphilis bacteria or antibodies are found. If no antibodies are found, it is called a nonreactive test.

Abnormal:

Abnormal results are called positive.

Syphilis bacteria or antibodies are found. If antibodies are found, it is called a reactive test.

A reactive or positive test result does not always mean that you have syphilis. Other conditions can cause positive test results. These include injecting illegal drugs, recent vaccinations, endocarditis, and autoimmune diseases.

The accuracy of testing often depends on the stage of syphilis. Testing may need to be repeated if:

  • Results of the first test are uncertain.
  • You have had repeated exposure to syphilis, such as from repeated unprotected intercourse.

Credits

Current as of: November 22, 2021

Author: Healthwise Staff
Medical Review:
Kathleen Romito MD - Family Medicine
E. Gregory Thompson MD - Internal Medicine
Martin J. Gabica MD - Family Medicine
Adam Husney MD - Family Medicine
Kevin C. Kiley MD - Obstetrics and Gynecology

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