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  • Also Known As:
  • Venereal Disease Research Laboratory
  • VDRL
  • Rapid Plasma Reagin
  • RPR Test
  • RPR Titer
  • Fluorescent Treponemal Antibody Absorption Test
  • Treponema pallidum Particle Agglutination Assay
  • TPPA
  • Microhemagglutination Assay
  • MHA-TP
  • Darkfield Microscopy
  • Automated Immunoassays for Syphilis Antibodies
  • Treponema pallidum by PCR
  • Formal Name:
  • Syphilis Detection Tests
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Test Quick Guide

Syphilis is a sexually transmitted disease (STD) caused by the bacteria Treponema pallidum. A syphilis infection is spread through contact with a syphilic sore, also called a chancre, usually during vaginal, anal, or oral sex. Syphilis can also be spread from a parent to a fetus in pregnancy or to an infant during childbirth. If not treated appropriately, syphilis may cause severe damage to internal organs.

Testing for syphilis is used in patients who have symptoms suggestive of this infection. Syphilis testing is also recommended to screen for syphilis in certain groups of people at an increased risk of infection or of transmitting the infection to others. Syphilis testing can be conducted using a sample of blood, a swab of fluid taken from a sore, or a sample of spinal fluid.

About the Test

Purpose of the test

The purpose of syphilis testing is to identify a syphilis infection. Syphilis tests may be prescribed for screening, diagnosis, or monitoring:

  • Screening for syphilis is testing for the infection in people without signs or symptoms of syphilis. Groups who benefit from screening include those at high risk of contracting syphilis as well as groups more likely to transmit this infection to others.
  • Diagnostic testing is recommended for people who have signs or symptoms that could be caused by syphilis. Syphilis can cause a wide range of symptoms, so doctors may recommend testing for syphilis even when symptoms aren’t severe or specific to this condition. Generally, diagnosing syphilis requires two tests: an initial screening test and a second confirmatory test.
  • Monitoring after treatment for syphilis is important to make sure that patients are responding to the prescribed treatment. Tests used to monitor patients include a physical exam to assess for changes in observable symptoms as well as laboratory blood tests to confirm a response to treatment.

What does the test measure?

Most forms of syphilis testing look for syphilis antibodies. Syphilis antibodies are substances in the blood that are made by the body’s immune system in people who come into contact with the bacteria that causes syphilis. Several types of antibody blood tests may be used to detect a syphilis infection.

Nontreponemal antibody tests detect antibodies that are not specific to the Treponema pallidum bacteria that causes syphilis. Although these antibodies are usually produced when a person has syphilis, they can also be produced in response to other conditions. People usually test negative for these antibodies after successful treatment for syphilis infection.

Nontreponemal antibody tests are usually used as an initial screening test and a positive result must be confirmed with another type of test. There are several types of nontreponemal antibody tests that may be used to detect and monitor syphilis:

  • Rapid plasma reagin (RPR) test: This test looks for the reagin antibody, which is often produced by the body in response to a syphilis infection.
  • Venereal Disease Research Laboratory (VDRL): A VDRL test measures antibodies that are often produced within one to two weeks after an infected person develops an initial sore. VDRL testing can be performed on blood or spinal fluid.

Treponemal antibody tests detect antibodies that are produced by the body only after infection with the bacteria that causes syphilis. Treponemal antibodies are detectable in the body earlier than nontreponemal antibodies and typically remain indefinitely. A person can still test positive for treponemal antibodies after completing syphilis treatment. This means that treponemal antibody tests cannot distinguish between a current and a past syphilis infection.

Treponemal tests are usually performed to confirm an infection after a patient has a positive result on a nontreponemal screening test. Some of the most common treponemal tests include:

  • Fluorescent treponemal antibody absorption (FTA-ABS) test
  • Microhemagglutination assay for antibodies to Treponema pallidum (MHA-TP)
  • Treponema pallidum hemagglutination assay (TPHA)
  • Treponema pallidum enzyme immunoassay (TP-EIA)
  • Chemoluminescence immunoassays (CLIA)

Most of the time, nontreponemal antibody tests are used to screen patients for syphilis while treponemal tests are used to confirm a patient’s diagnosis. In some cases, a patient’s doctor may start by screening a patient with a treponemal antibody test and then confirm a positive result using a nontreponemal antibody test. This testing strategy is called reverse sequence testing.

Less common methods to detect syphilis look for the bacterium itself or test for its genetic material. These test include:

  • Darkfield microscopy: This method of detecting syphilis uses a sample of fluid from a skin sore or a lymph node. The sample is analyzed using a specially designed microscope under which the Treponema pallidum bacteria look bright against a dark background.
  • Polymerase chain reaction (PCR) testing: PCR testing detects the genetic material, called DNA, of the Treponema pallidum bacteria.

When should I get a syphilis test?

Adults without symptoms should be screened for syphilis only if they are at an increased risk of infection or of transmitting the infection to others. Factors that increase a person’s risk of contracting syphilis and indicate the need for annual screening include:

  • Being male and under age 29
  • Having a history of incarceration
  • Involvement in commercial sex work
  • Living in an area with high syphilis infection rates
  • Being Black or African American

Other groups also benefit from regular screening at certain intervals. These groups include:

  • Pregnant people at first prenatal visit, at 28 weeks, and again at delivery if high risk.
  • Men and anyone with a penis who is sexually active and has sex with another person with a penis should be tested annually. More regular testing may be recommended if they have additional risk factors.
  • Transgender and gender diverse people should be screened annually depending on sexual behaviors and risk of exposure.
  • People diagnosed with HIV may be screened at their first HIV evaluation, then one or more times each year depending on their behaviors and local infection rates.

Anyone with symptoms of syphilis should receive diagnostic testing. Without treatment, a syphilis infection progresses through three stages: primary syphilis, secondary syphilis, and tertiary syphilis. These three stages are separated by periods in which no symptoms are present. In any stage of syphilis, the infection can spread to the brain and nervous system, called neurosyphilis. Syphilis can also spread to the eye, called ocular syphilis, or to the ears, called otosyphilis.

The signs and symptoms of syphilis vary based on the stage of an infection:

Finding a Syphilis Test

How to get tested

Testing to detect syphilis is typically ordered by a health care professional. To screen patients without symptoms, a doctor or other health care professional can evaluate the individual’s risk of syphilis and suggest a schedule for screening.

For patients experiencing symptoms, the health care professional will determine the most appropriate test(s) to diagnose or rule out syphilis as the cause.

Syphilis testing can be performed in a medical setting such as a hospital, doctor’s office, or clinic, or at a health program in an individual’s community.

Can I take the test at home?

At-home test kits are available for individuals seeking to test for syphilis from home. At-home syphilis test kits provide the materials needed to collect a small sample of blood and mail it to a laboratory for analysis. At-home testing kits offer a convenient way to screen for syphilis at home, but positive test results will require additional confirmation testing ordered by a doctor.

How much does the test cost?

When ordered by a doctor, the cost of testing for syphilis may be covered by a patient’s health care insurance. Patients should talk to their health insurance provider about specific patient costs, which may include copays and deductibles.

Other times, syphilis testing may be paid for out of pocket. In addition to the cost of the test itself, patients may be responsible for additional costs such as an exam fee, technician fees, and the cost of any test conducted at the same time.

For patients concerned about the cost of syphilis testing, it may be helpful to contact a local health department or community-based organizations that provide low-cost or free STD testing.

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Taking a Syphilis Test

Syphilis testing is most often performed using a blood sample. Testing can also be performed using fluid swabbed from a syphilis sore or spinal fluid. Spinal fluid is collected in a special procedure called a lumbar puncture.

Samples used for syphilis testing are generally collected by a medical professional.

Before the test

No special preparations are necessary before a syphilis test that uses a sample of blood or fluid from a sore.

Before a lumbar puncture, patients may be instructed to go to the bathroom to empty their bladder and bowels.

During the test

During a blood sample collection, blood is drawn from a vein on the inside of the elbow or on the back of the hand. First, the site is cleaned and an elastic band is tied around the arm to increase blood flow, and then a needle is placed into the vein and blood is collected into a vial or tube. Once sufficient blood has been collected, the elastic band is removed before the needle is taken out.

When a sample of fluid taken from a sore is used for syphilis testing, the health professional will use a swab or brush to collect fluid from the area of suspected infection. The collection process may be uncomfortable, although the discomfort is usually very brief.

To collect a sample of spinal fluid, doctors perform a procedure called a lumbar puncture. During a lumbar puncture, patients are instructed to lie on their side. A health care provider cleans an area on the patient’s back and injects an anesthetic that reduces pain during the procedure. Once the back is numb, a thin needle is inserted into the spine and a small sample of cerebrospinal fluid (CSF) is withdrawn for testing. This procedure takes about five minutes to complete.

After the test

Once a blood draw is finished, patients may be asked to apply pressure to the injection site and are given a bandage to reduce any additional bleeding.

There are few risks to having blood drawn or a sample of fluid taken from a sore. There are no restrictions on resuming regular activities after the test is finished.

After a lumbar puncture, patients may be instructed to remain lying down for one or two hours after the procedure to prevent a headache. Some patients experience temporary pain and tenderness where the needle was inserted into their back.

Syphilis Test Results

Receiving test results

Syphilis test results may be available from within a few hours to several days, depending on the type of syphilis test being conducted.

Patients may receive syphilis test results over the phone, during a follow-up appointment with their doctor, or in an electronic medical record.

Interpreting test results

The way in which the results of syphilis tests are reported depend on the type of test conducted.

Results of nontreponemal testing may be reported as positive, also called reactive, or negative, also called non-reactive. If positive, the results may also indicate the amount of antibody present in the sample used for testing.

A positive nontreponemal test result means that a patient may have syphilis. A follow-up treponemal test is required to confirm a positive diagnosis. Negative test results indicate that a patient may not have syphilis, although additional testing may be needed if a patient is experiencing symptoms.

For treponemal testing, results are typically reported as reactive or nonreactive. A reactive test result indicates that a patient has had syphilis at some point in the past. Because a patient who has been treated for syphilis can continue having reactive results indefinitely, doctors take into account a person’s health history when interpreting positive test results. A nonreactive treponemal test result indicates that antibodies to syphilis weren’t detected and a patient is unlikely to have an infection.

It’s important to discuss test results with a doctor or other health care professional who can help patients understand their test results.

Are test results accurate?

Both nontreponemal and treponemal antibody tests are important methods for detecting syphilis infections and preventing complications of this disease. Inaccurate results can occur, which is why doctors use strategies such as performing multiple tests to confirm positive results and taking a careful medical and sexual history to help interpret test results correctly.

Several conditions can cause a false positive result on a nontreponemal test, which means that the test result is positive despite the patient not having a syphilis infection. These conditions include IV drug use, HIV/AIDS, hepatitis B, Lyme disease, certain types of pneumonia, malaria, and autoimmune diseases.

False negative nontreponemal test results occur when a person tests negative, but they actually do have a syphilis infection. The most common reason for a false-negative result is that the antibodies detected in this type of syphilis test may not develop until 3 to 6 weeks after infection. Nontreponemal testing is also less accurate in patients in the tertiary stage of syphilis.

False positive test results can also occur in treponemal testing in patients who have been successfully treated for syphilis in the past. False negative test results may occur in treponemal tests during the first several weeks after infection.

Do I need follow-up tests?

In patients who are treated for syphilis, doctors measure treatment effectiveness by conducting nontreponemal tests and monitoring symptoms. The frequency of testing during treatment depends on the stage of a patient’s infection and whether or not the patient is also diagnosed with HIV.

If the results of nontreponemal tests are negative, testing may be repeated after six weeks if doctors believe that a syphilis infection is likely.

Patients with syphilis should also be tested for other STDs, both at diagnosis and six months later.

Questions for your doctor about test results

If you’ve recently received the results of a syphilis test, it may be beneficial to ask your doctor for additional information in understanding your result and planning for future testing. Helpful questions for you doctor include:

  • What is my syphilis test result?
  • Based on my test results, are any additional tests needed?
  • How can I talk to my sexual partners about my test result?
  • How often should I be tested for syphilis and other STDs?

View Sources


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