Why It Is Done
A test for syphilis is done to:
Screen for syphilis or monitor treatment for a syphilis infection using the venereal disease research laboratory (VDRL) or rapid plasma reagin (RPR) test.
Confirm that a syphilis infection is present using the fluorescent treponemal antibody absorption (FTA-ABS) or the Treponema pallidum particle agglutination assay (TPPA) test.
Screen pregnant women for syphilis. Prenatal syphilis testing is required by law in all states.
Some states require the VDRL screening test before a couple can obtain a marriage license.

How To Prepare
Tell your health professional if you are taking any antibiotics.
If you may have syphilis, you should avoid sexual contact until the test results show you are not infected or until you and your sexual partner or partners have completed treatment and the infection has been cured.

Talk to your health professional about any concerns you have regarding the need for the test, its risks, or how it will be done. Complete the medical test information form to help you understand the importance of the test.

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.

Sore or skin sample
For a darkfield microscopic examination, a sample of fluid or tissue may be taken from an open sore (chancre) or from a rash suspected to be caused by syphilis. A fluid sample is obtained by gently pressing the chancre. Skin or mucous membrane samples may be obtained by gently rubbing a cotton-tipped swab over the area affected.

Blood sample
The health professional drawing blood will wrap an elastic band around your upper arm to temporarily stop the flow of blood through the veins of your arm. This makes it easier to place the needle into a vein properly because the veins below the band get larger and do not collapse easily.

The needle site is cleaned with alcohol and the needle is inserted. More than one needle stick may be needed if the needle does is not placed correctly or if the vein cannot supply enough blood.

When the needle is properly placed in the vein, a collection tube will be attached to the needle and blood will flow into it. Sometimes more than one tube of blood is collected.

When enough blood has been collected, the band around your arm will be removed. A gauze pad or cotton ball is placed over the puncture site as the needle is withdrawn. Pressure is applied to the puncture site for several minutes and then a small bandage is often placed over it.

Spinal fluid sample
A 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. Once the needle is in place, a small amount of cerebrospinal fluid (CSF) is removed from the spinal canal. For more information, see the medical test Lumbar Puncture.

How It Feels
Sore or skin sample
You may have some discomfort when fluid is collected from an open sore (chancre), but chancres usually are not very tender or painful.

Blood sample
You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. However, many people do not feel any pain (or have only minor discomfort) once the needle is positioned in the vein. The amount of pain you feel depends on the skill of the health professional drawing the blood, the condition of your veins, and your sensitivity to pain.

Spinal fluid sample
You may have some discomfort during a lumbar puncture to collect spinal fluid for syphilis testing. For more information, see the medical test Lumbar Puncture.

Risks
Sore or skin sample
There is very little risk of complications from having a sample taken from an open sore (chancre), skin rash, or mucous membrane.

Blood sample
There is very little risk of complications from having blood drawn from a vein. You may develop a small bruise at the puncture site. You can reduce the risk of bruising by keeping pressure on the site for several minutes after the needle is withdrawn.

Rarely, the vein may become inflamed after the blood sample is taken. This condition is called phlebitis and is usually treated by applying a warm compress several times daily.

Continued bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medications can also make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medication, tell the health professional before your blood is drawn.

Spinal fluid sample
There is little risk associated with having a lumbar puncture to obtain a spinal fluid sample for syphilis testing. For more information, see the medical test Lumbar Puncture.

What Affects the Test
The use of antibiotics before having a syphilis test may cause falsely nonreactive or negative results.
A blood transfusion in the weeks before having a syphilis test may cause inaccurate test results.