The rapid plasma reagin (RPR) blood test is a test that provides a rapid response to determine if there are antibodies present in the blood. This is typically used to indicate that the organism which causes syphilis is present. It is considered a non-specific test because it is looking for antibodies that the body will release against the substances that the bacteria releases in the body instead of bacterial-specific antibodies.
In addition to determining if the bacteria is present, the RPR blood test can also be used to monitor disease progression to determine if a treatment plan that has been implemented is effective.
When To Have the RPR Blood Test
The signs and symptoms of syphilis may take up to 90 days to present themselves. The most common symptom is a sore that occurs on the entry point of the bacteria in the body. Although it is called a “sore,” it is usually not painful and is round and firm. It will last up to 6 weeks and eventually go away even if treatment for the infection is not received.
Because the most common symptom is this single sore, men who have vaginal intercourse can typically discover this entry point symptom more commonly then those who practice other sexual activities.
After 6 weeks of a syphilis infection, a rash may begin to appear on one or more areas of the body. It may appear just as the sore is healing or occur several months afterward. The rash that presents itself is usually not itchy and can appear anywhere, including the soles of the feet or the palms of the hand.
In the chronic stage of infection, which may not occur until 10-30 years after the infection date, skin nodules or lesions will begin to appear. There may also be cardiovascular symptoms present and changes in how the central nervous system operates.
What Do My Test Results Mean?
In general terms, a positive RPR blood test will indicate that there is a strong likelihood that the bacteria which causes syphilis is present and a negative test indicates it is not present. False results are somewhat common, however, so if a medical provider suspects syphilis and the test results do not match, then additional testing will generally be ordered.
Although it is considered a rapid test, the results can take as long as 3-5 days to be received.
This test is especially important for women who are pregnant or are thinking about becoming pregnant because the bacteria which causes syphilis can cause numerous fetal health problems. From low birth weights to premature delivery to instances of stillbirth, there can also be complications after birth as well. Congenital syphilis may cause seizures, hearing loss, and cataracts. Some cases of congenital syphilis are not even notice until the adolescent years.
For this reason, it is recommended that all women receive the RPR blood test during their pregnancy and at delivery to eliminate the possibility of ongoing issues related to syphilis. Most women will receive their first test at the time of their first prenatal visit if CDC recommendations are followed by a medical provider.
Here’s What You Need to Know
Many people may be infected with the bacteria which causes syphilis and never even know it. This is because many infections do not cause physical symptoms to present. The RPR blood test can detect the antibodies that are present, however, to determine that the bacteria is indeed present.
False test results are also common with the RPR blood test. The presence of certain viruses, including hepatitis and varicella, measles, malaria, TB, and other autoimmune diseases can cause this test to come back as positive. A pregnancy has also been known to cause false positive results on occasion. Even something as simple as IV drug use or a contaminated needle can cause a false positive result, as can the simple act of aging.
For this reason, a positive RPR blood test may be followed up by additional tests to determine if there is a specific condition which needs to be treated. Once syphilis reaches the chronic stage at the 10-30 year mark, the RPR blood test is no longer a viable method of detection and other forms of syphilis testing will be required.
Having a sore from syphilis makes a person more likely to be infected with other sexually transmitted disease if sexual activities are continued. HIV infections are up to 5x more likely. Any sores or rashes in the genital area should be examined by a medical provider immediately.