About the Test
Purpose of the test
The purpose of syphilis testing is to identify a syphilis infection. Tests may be prescribed for screening, diagnosis, or monitoring:
- Diagnostic testing is recommended if you have signs or symptoms that could be caused by syphilis. It 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.
- Screening for syphilis is testing for the infection in people without signs or symptoms of the disease. Groups who benefit from screening include those at high risk of contracting syphilis as well as those more likely to transmit this infection to others.
- Monitoring after treatment for syphilis is important to make sure you are responding to the prescribed treatment. Tests used to monitor you 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, substances in the blood 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. You can 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 looks for the reagin antibody, which is often produced by the body in response to 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 produced by the body only after infection with the bacteria that causes syphilis. This type of antibody is detectable in the body earlier than nontreponemal antibodies and typically remains indefinitely. You can still test positive for treponemal antibodies after completing syphilis treatment. This means that treponemal antibody tests cannot distinguish between a current and past syphilis infection.
Most of the time, nontreponemal antibody tests are used to screen for syphilis while treponemal tests are used to confirm the diagnosis. In some cases, a doctor may start by screening you 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 tests 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: This 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
- Involvement in commercial sex work
- Living in an area with high syphilis infection rates
Other groups also benefit from regular screening at certain intervals. These groups include:
- Pregnant people at the 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 should receive diagnostic testing. Without treatment, 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 infection:
Finding a Syphilis Test
How can I get a syphilis test?
Testing to detect syphilis is typically ordered by a health care professional. To screen you without symptoms, a doctor or other health care professional can evaluate your risk of syphilis and suggest a schedule for screening.
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. Tests can also be ordered online.
You can order a home STD testing kit (with treatment included) with testing by a Clinical Laboratory Improvement Amendments (CLIA)-approved lab.
Can I take the test at home?
At-home test kits are available for individuals seeking to test for syphilis from home. These 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 from your home, but positive test results will require additional confirmation testing ordered by a doctor.
You can order a test kit online and take your sample to a local lab for testing, with results in two to five days.
How much does the test cost?
When ordered by a doctor, the cost of testing for syphilis may be covered by your health care insurance. Talk to your health insurance provider about specific 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, you may be responsible for costs such as an exam fee, technician fees, and the price of any test conducted at the same time.
If you are 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.
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, you may be instructed to go to the bathroom to empty your 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 care 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. You are instructed to lie on your side. A health care provider cleans an area on your 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, you 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, you may be instructed to remain lying down for one or two hours after the procedure to prevent a headache. You may experience slight temporary pain and tenderness where the needle was inserted into your back.
Syphilis Test Results
Receiving test results
Syphilis test results may be available within a few hours to several days, depending on the type of syphilis test being conducted.
You may receive syphilis test results over the phone, during a follow-up appointment with your doctor, or in an electronic medical record.
Interpreting test results
The way in which the results of syphilis tests are reported depends 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 you may have syphilis. A follow-up treponemal test is required to confirm a positive diagnosis. Negative test results indicate that you may not have syphilis, although additional testing may be needed if you are experiencing symptoms.
For treponemal testing, results are typically reported as reactive or nonreactive. A reactive test result indicates you have had syphilis at some point in the past. Because even if you have been treated for syphilis you can continue having reactive results indefinitely, doctors take into account your health history when interpreting positive test results.
A nonreactive treponemal test result indicates that antibodies to syphilis weren’t detected and you are unlikely to have an infection.
It’s important to discuss test results with a doctor or other health care professional who can help you understand 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 your doctor include:
- What is my syphilis test result?
- Based on my test results, are any additional tests (or follow-up tests) needed?
- How can I talk to my sexual partner(s) about my test result?
- How often should I be tested for syphilis and other STDs?