Quick Facts
- Sample: Blood (serum or plasma)
- Fasting: No fasting required
- Turn-around: 1-2 business days. May take longer based on weather, holiday, or lab delays.
Benefits
- Fast, confidential screening for syphilis without a doctor's visit
- Early detection helps prevent serious complications and stops transmission
- Simple blood draw with no fasting or special preparation needed
- Convenient online ordering with flexible local lab collection options
- Affordable direct-to-consumer access for proactive sexual health management
Who Is This Test For?
- Sexually active individuals seeking routine STI screening or peace of mind
- Pregnant women as part of prenatal care to prevent congenital syphilis
- People with symptoms like painless sores, unexplained rashes, or swollen lymph nodes
- Individuals at higher risk due to multiple partners or unprotected sex
- Those with a positive partner who recently tested positive for syphilis
- Anyone needing confirmation after a reactive treponemal screening test
- Patients monitoring treatment to verify syphilis therapy is working effectively
How It Works – Just 3 Steps
- Order online – Purchase your test online and receive a lab requisition form
- Visit a lab – Get a simple blood draw at any nearby partner lab
- Get results – Secure, confidential results delivered in 1–2 business days.
FAQ
What does this test measure? This test detects reagin antibodies produced when your body fights Treponema pallidum, the bacteria causing syphilis.
Is this test accurate? RPR has 78–86% sensitivity in primary and secondary syphilis and over 90% specificity for screening (NCBI StatPearls 2023).
Can I get a false positive result? Yes, conditions like lupus, pregnancy, or recent infections can cause biological false positives; confirmation testing is essential.
Do I need to fast before the test? No fasting is required, but disclose recent illnesses or vaccinations to your provider.
What happens if my result is reactive? A reactive result suggests possible syphilis and requires confirmation with treponemal-specific tests like FTA-ABS or TP-PA.
How soon can this test detect syphilis? RPR typically becomes positive 1–4 weeks after infection, making it useful for early detection (CDC 2024).
More Details
What is the purpose of this test?
The RPR (Rapid Plasma Reagin) Blood Test screens for syphilis by detecting nonspecific antibodies called reagins that your body produces in response to Treponema pallidum infection (Mayo Clinic 2024). These antibodies target lipoidal material released from damaged cells or the bacterium itself. The test uses flocculation or immunochromatographic methods to identify these antibodies in your blood serum or plasma. A reactive result indicates possible active syphilis infection and prompts confirmatory testing with treponemal-specific assays. Healthcare providers also use RPR to monitor treatment effectiveness by tracking antibody levels over time (CDC 2024).
Who would benefit from this test?
This test benefits sexually active individuals seeking confidential STI screening, especially those with multiple partners or unprotected sexual contact. Pregnant women need RPR testing during prenatal care since untreated syphilis can cause serious birth defects or stillbirth (CDC 2024). People experiencing symptoms like painless genital sores, unexplained skin rashes, or swollen lymph nodes should get tested promptly. Those whose partners tested positive for syphilis need screening even without symptoms. Individuals receiving positive results from treponemal screening tests require RPR confirmation. Patients undergoing syphilis treatment need periodic RPR testing to verify therapy success (Public Health Ontario 2019).
When should I order RPR (Rapid Plasma Reagin) Syphilis Blood Test, Qualitative?
Order this test when you have symptoms suggesting syphilis, including painless sores or ulcers on genitals, mouth, or rectum. Get tested if you notice unexplained skin rashes, especially on palms or soles, or experience fever and swollen lymph nodes. Pregnant women should test during their first prenatal visit and again in the third trimester if at high risk (CDC 2024). Consider testing after risky sexual behavior or if your partner recently tested positive. Healthcare providers recommend RPR to confirm reactive results from treponemal screening tests. Patients who've completed syphilis treatment need follow-up RPR testing at 6, 12, and 24 months to monitor antibody levels and detect possible reinfection (UCSF Health 2024).
How do I interpret the results?
Reactive (Positive)
- Meaning: Reagin antibodies detected; suggests active or recent syphilis infection
- Typical action: Requires confirmatory treponemal testing (FTA-ABS, TP-PA); begin treatment if confirmed
Nonreactive (Negative)
- Meaning: No detectable reagin antibodies; typically excludes syphilis
- Typical action: No immediate action unless tested too early; retest in 2–4 weeks if recent exposure
False Positive
- Meaning: Reactive result caused by other conditions (e.g., lupus, pregnancy, infections)
- Typical action: Clinical evaluation and treponemal testing to rule out true syphilis infection
With over 150,000 reported U.S. syphilis cases in 2024, RPR screening remains essential for early detection and preventing serious complications (CDC 2024).
Disclaimer: Reference ranges may vary by laboratory. Listed ranges are general guidelines and may differ from those used by the performing lab. Always consult your healthcare provider for interpretation.
Pre-test preparation
No fasting is required before your RPR blood test. You can eat and drink normally before your appointment. However, inform your healthcare provider about recent illnesses, vaccinations, or infections, as these may affect test accuracy. Disclose any autoimmune conditions like lupus or rheumatoid arthritis that could cause false-positive results. If you're pregnant, let your provider know since pregnancy can sometimes trigger biological false positives. Avoid applying lotions or creams to your arm on test day to ensure clean venipuncture. Bring your lab requisition form and photo ID to your appointment (NCBI StatPearls 2023).
How often should I get tested?
- High-risk individuals (multiple partners, unprotected sex): every 3–6 months or after each new partner
- Pregnant women: first trimester and third trimester (if high risk)
- People with HIV: at diagnosis, then annually or more frequently if symptomatic
- Post-treatment monitoring: 6, 12, and 24 months after completing therapy
- Average-risk individuals: during routine health screenings or if symptoms develop
- After known exposure: immediately, then repeat at 6 weeks if initially negative
Why early detection matters
Early syphilis detection through RPR testing prevents serious health complications that develop in untreated cases. Without treatment, syphilis progresses through stages, potentially causing neurological damage, cardiovascular disease, blindness, and organ failure years after initial infection (CDC 2024). Pregnant women with untreated syphilis face high risks of stillbirth, premature birth, or congenital syphilis causing severe infant disabilities. Early diagnosis allows prompt antibiotic treatment that cures the infection and prevents transmission to sexual partners. Regular screening helps identify asymptomatic cases since many people don't realize they're infected. With syphilis rates rising nationally, proactive testing protects both your health and public health (NCBI 2023).
Related tests you may consider
Treponema pallidum Antibodies (FTA-ABS) Serum Test– Test to confirm Syphilis by detecting antibodies of Treponema pallidum.
Human Immunodeficiency Virus 1 and 2 (HIV-1/2) Preliminary Blood Test (4th generation) – Is for a standard rapid test for routine HIV Screening, it looks for both antibodies to the HIV virus and the p24 Antigen which is specific to HIV.
Herpes Simplex Virus (HSV) Types 1 and 2 Specific Antibodies Blood Test, IgG – Checks for past herpes infections by looking for antibodies in your blood, even if you’ve never had symptoms, and helps you and your doctor understand your sexual health better.
Hepatitis Blood Test Panel, Acute– Helps detect and diagnose acute liver infection and inflammation that is due to one of the three most common hepatitis viruses: hepatitis A virus (HAV), hepatitis B virus (HBV), or hepatitis C virus (HCV).
