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Over the years, there have been many serological tests for syphilis disease. The Laboratory ultimately decides which tests it will use. In general, we will perform a highly sensitive but somewhat non-specificrapid screening test and a highly sensitive and specific confirmatory test. Both types of tests can be performed on one sample of patient serum.


  • Serologic Test for Syphilis
    • Rapid Plasma Reagin (RPR)
    • Venereal Disease Research Laboratory (VDRL)
    • Treponema Pallidum-Particle Agglutination (TP-PA)
    • Fluorescent Treponema Antibody (FTA)


  1. Obtain 5-10 ml of blood from the patient using standard venipuncture technique. Collect the blood into an anticoagulant free (i.e. "clot") tube or serum separator tube (SST). Plasma (purple top tube) may be used up to 48 hrs. from collection.
  2. Label tube with patient’s name and date of collection.
  3. Complete the Test Requisition Form or order request online through our Laboratory Information Management System (LIMS). Specimen and forms should be placed in a designated location at each site for the lab courier to pick up.
  4. Allow specimen to clot and label with a unique identifier to match requisiion form. Wherever a centrifuge is available, specimens should be spun on the same day of collection. Arrange for transport to laboratory. If transportation is delayed, refrigerate tube to minimize hemolysis.


DARKFIELD EXAMINATION is the only direct test for syphilis infection and is only effective when lesions are present. Since lesions may only be present for a few weeks during the early course of the disease it is often necessary to use serological tests for diagnosis. This test requires a special microscope and is no longer performed in our lab.

PREMARITAL TESTING - Delaware no longer has a requirement for premarital screening for syphilis. The laboratory does perform premarital testing for clients who are obtaining marriage licenses in states that still have such a requirement and will provide the results on a form accepted by that state.

SEROLOGIC TESTS FOR SYPHILIS (STS): Two types of antibodies are measured by these tests:

  • Nonspecific "non-treponemal" antibody screening tests (i.e. RPR, VDRL). These reaginic antibodies, while almost always produced by patients with syphilis, may also be produced by patients with other infectious diseases, autoimmune disorders, pregnancy, old age and recent immunization. Positive screening in this category should be confirmed.
  • Specific "treponemal" antibody tests (i.e. TP-PA, FTA) are used to confirm positive screening tests, or occasionally as confirmation when other test results or clinical symptoms warrant additional testing.


Expected turnaround is 1-3 workdays for both negative and positive reports. Positive results are confirmed with the more specific confirmatory test. Patients previously confirmed positive do not warrant repeat confirmatory testing.

Negative screening tests are not routinely confirmed unless certain and rare extenuating circumstances, such as untreated tertiary syphilis, are present. Contact the laboratory if it is suspected that the patient falls into this category.

FTA’s are sent to a reference lab and require 2-3 weeks.


Samples will be rejected if they are:

  • Unlabeled - All specimens MUST be appropriately labeled.
  • Insufficient in Quantity - No specimen received, no specimen in container, or less than 1.0 mL of blood received.
  • Hemolyzed - Specimens must be free of hemolysis.
  • Damaged - Specimen leaked or broken transit.
  • Too Old - Samples greater than 5 days old are unreliable specimens for testing.

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