What Is RPR Lab Test?

A rapid plasma reagin test also called the RPR lab test, is one of the numerous tests that screen for sexually transmitted diseases (STDs). It’s just like a regular blood test that is used to detect syphilis antibodies. 

RPR Lab Test

What Is Syphilis?

Syphilis is a sexually transmitted infection (STI), that is usually spread during unprotected sexual contact. The main cause of the infection is a bacteria called treponema pallidum. It enters the body through a mucous membrane or cuts on your skin. It isn’t unusual to not experience any symptoms, and sometimes it’s quite hard to determine if syphilis is the main cause of the problem. The early stage might seem just like any other disease, and it manifests as a painless sore on your mouth, rectum, and genitals. Still, doctors say that in specific cases the bacteria remains inactive in the body for decades before getting active again. 


As we mentioned, syphilis is developing in stadiums, and early ones are easy to cure while refusing treatment might cause serious heart damage or even death. Many people say that they have been infected for years and didn’t notice any symptoms, so here are all the phases and how to recognize them: 

  • The first stage

The first phase includes a little painless sore on the place where bacteria entered your body. It’s called a chancre, and some patients develop more than one. The approximate time of developing the primary sore is about three weeks after the exposure. Because of its painless nature, it can stay unnoticed and hidden within your vagina.

  • Secondary syphilis

In the following weeks, when your first sore heals, the rush that starts on your trunk and suddenly covers your entire body will become visible. It can appear even on your palms. This rush is not itchy, but many women say that they experienced fever, muscle pain, and swollen throat and lymph nodes. This process will stop in the next few weeks and then appear from time to time. 

  • Latent syphilis 

In this stage, syphilis disappears, or better say enters the hidden (latent) stage. It might last for years, even decades, but it also can progress to the worst stages such as tertiary syphilis. 

  • Tertiary syphilis

This late stage includes numerous complications that are a direct result of refusing treatment. It leads to nerve, heath, brain, liver, and bone damage. Sometimes, consequences are fatal.

  • Congenital syphilis

Preventing congenital syphilis is the crucial reason for future mothers to go to STD testing. This type of syphilis is transferred from mother to newborn through the placenta or during birth. Consequences are not visible at first, but rash and sores on the palms and feet can turn into deafness, teeth deformation, and forming a saddle nose.

How Does the RPR Lab Test Look?

The procedure itself is like regular blood testing. Your doctor will wrap the elastic band on your upper arm and insert the needle to draw a necessary amount of blood. Your test results should be done within 7-10 days. 

  • Negative results are usually a good sign, and they mostly mean that you don’t have syphilis. Still, don’t get too excited, because sometimes results can be false-negative. Even if it’s proven that you are not infected, you should always go and test at least once a year. 
  • Positive RPR lab test results mean that you are infected, but further analyses are necessary to determine the stage of your disease and start with treatment. 
  • False-negative results can refer to: 
    • Early stages of syphilis
    • You are infected less than 14 days
    • You still have alcohol in your blood 
  • False-positive RPR lab test results mean:
    • Pregnancy
    • Intravenous drug use 
    • Respiratory infections
    • Liver disease


When you diagnose it on time, syphilis is easy to cure in the early stages. The fastest way is using penicillin shots, or if you are allergic, your doctor will find a suitable replacement in the form of an antibiotic. Also, penicillin is the only possible method of treating syphilis during pregnancy, but still, your baby should get tested just in case. 


Taking care of your reproductive health should be on the top of the list of your yearly medical appointments. Regular testing on STDs should be done at least once a year if you are a sexually active adult. On the other side, if you are changing partners or have symptoms, tests should be done every 3-6 months. Other than the RPR lab test, follow-up treatment for syphilis is available in our women’s clinic. If you are tested positive, you’ll need the FTA-ABS test, TPPA test or darkfield microscopy to determine the cause and receive the treatment. We also advise you to do HIV testing on your regular exam.