The RPR (rapid plasma reagin) test is a non‑treponemal blood assay that screens for syphilis by detecting reagin antibodies produced in response to cellular damage. It’s used for initial screening and to monitor treatment via quantitative titers. False positives can occur with other infections, autoimmune conditions, or pregnancy, so reactive RPR results require confirmation with a treponemal-specific test.

If an RPR test is positive, it suggests a current or recent syphilis infection but can also reflect false positives from other conditions (e.g., pregnancy, autoimmune disease, other infections). A positive RPR should be confirmed with a treponemal test (e.g., TPPA or FTA‑ABS). Quantitative RPR titres help assess disease activity and monitor treatment response. Confirmed cases are treated (usually penicillin) with partner notification and follow‑up.

RPR stands for Rapid Plasma Reagin. It is a non-treponemal blood test used to screen for syphilis by detecting reagin antibodies produced in response to cellular damage from Treponema pallidum. RPR is useful for initial diagnosis and monitoring treatment response but can give false positives; reactive results should be confirmed with specific treponemal tests.

RPR is generally preferred for routine syphilis screening because it’s simpler to perform, easier to read or automate, and more stable. VDRL remains useful for cerebrospinal fluid testing and certain lab contexts. Both are non-treponemal tests that can yield false positives or negatives, so reactive results should be confirmed with a specific treponemal test.

RPR is a useful, rapid non-treponemal screening test for syphilis: sensitive in secondary disease and valuable for monitoring treatment because titers fall after successful therapy. However it can yield false positives (other infections, autoimmune disease, pregnancy) and is less sensitive in very early or late disease. Positive RPR requires confirmation with a treponemal-specific test; it’s not sufficient alone for definitive diagnosis.

Syphilis is caused by the bacterium Treponema pallidum, a spiral-shaped (spirochete) organism. It’s usually transmitted through direct sexual contact with infectious lesions and can pass from an infected pregnant person to the fetus (congenital syphilis). The infection progresses through primary, secondary, latent and tertiary stages if untreated and is diagnosed by blood tests; penicillin is the standard effective treatment.