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Syphilis Tests

Syphilis tests detect antibodies to the bacterium that causes syphilis (Treponema pallidum) in blood, body fluid, or tissue. The tests are used to screen for or to confirm a syphilis infection.

Syphilis is a sexually transmitted infection (STI) that is usually spread during sexual contact, including kissing or oral sex.

Tests used to screen for syphilis include:

  • Venereal disease research laboratory (VDRL) test. The VDRL test checks for an antibody that can be produced in people who have syphilis. This antibody is not produced as a reaction to the syphilis bacteria specifically, so this test is sometimes not accurate. The VDRL test may be done on a sample of blood or spinal fluid. The VDRL test is not very useful for detecting syphilis in very early or advanced stages.
  • Rapid plasma reagin (RPR) test. The RPR test also detects syphilis antibodies.
  • Enzyme immunoassay (EIA) test. This is a newer blood test that checks for antibodies to the bacteria that cause syphilis. A positive EIA test should be confirmed with either the VDRL or RPR tests.

Tests used to diagnose syphilis include:

  • Fluorescent treponemal antibody absorption (FTA-ABS) test. The FTA-ABS test checks for antibodies to the bacteria that cause syphilis and can be used to detect syphilis except during the first 3 to 4 weeks after exposure to syphilis bacteria. The test can be done on a sample of blood or spinal fluid.
  • Treponema pallidum particle agglutination assay (TPPA). The TPPA test is used to confirm a syphilis infection after another method tests positive for the syphilis bacteria. This test detects antibodies to the bacteria that cause syphilis. This test is not done on spinal fluid.
  • Darkfield microscopy. This test uses a special microscope to examine a sample of fluid or tissue from an open sore (chancre) for the syphilis bacteria. This test is used mainly to diagnose syphilis in an early stage.
  • Microhemagglutination assay (MHA-TP). The MHA-TP is used to confirm a syphilis infection after another method tests positive for the syphilis bacteria.

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.

A test for syphilis is done to:

  • Screen for syphilis or check treatment for a syphilis infection. 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.
    • Some states require the VDRL screening test before a couple can obtain a marriage license.
    • The Centers for Disease Control and Prevention (CDC) and the U.S. Preventive Services Task Force (USPSTF) recommend that all pregnant women be screened for syphilis early in pregnancy.1, 2
  • Confirm that a syphilis infection is present.

Screening for syphilis and other sexually transmitted infections (STIs) is often done for people who engage in high-risk sexual behavior. 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.

1 | 2 | 3 | 4

WebMD Medical Reference from Healthwise

Last Updated: September 29, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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