RPR, or Rapid Plasma Reagin, is a blood test used to screen for syphilis, a sexually transmitted infection. It detects non-specific antibodies that the body produces in response to the infection. The test is quick and inexpensive, making it a common choice for initial screening. If the RPR test is positive, further testing is usually required to confirm the diagnosis of syphilis. This may include more specific tests, such as the Treponema pallidum particle agglutination assay (TP-PA). Early detection and treatment are crucial to prevent complications associated with the disease.