A Syphilis Screen (VDRL/RPR) is a blood test used to screen for syphilis, a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. VDRL (Venereal Disease Research Laboratory) and RPR (Rapid Plasma Reagin) are similar tests that look for “reagin” antibodies—proteins your immune system may produce in response to cell damage that can occur with syphilis infection. Because these are non-treponemal tests, they do not detect the bacteria directly; instead, they detect an antibody pattern that is commonly present in syphilis.

Results are usually reported as reactive (positive) or non-reactive (negative), and may also include a titer (a number such as 1:2, 1:8, 1:32) that estimates antibody level.

What the results can mean:

Non-reactive (negative): Often means there is no evidence of syphilis. However, very early infection may not be detected yet (a “window period”), and late syphilis can occasionally yield low or negative titers. If risk is high or symptoms are present, repeat testing or additional tests may be recommended.

Reactive (positive): Suggests possible syphilis, but confirmation is needed because false positives can occur (for example, with some autoimmune conditions, pregnancy, older age, or other infections). A reactive VDRL/RPR is typically followed by a treponemal confirmatory test (such as TP-PA, FTA-ABS, or treponemal EIA/CIA).

Titer changes over time: Titers often correlate with disease activity. After successful treatment, the titer usually declines over months. For this reason, VDRL/RPR is commonly used not only for screening but also for monitoring response to treatment or identifying possible reinfection.

This syphilis screening test may be ordered as part of routine STI testing, during pregnancy, or when symptoms or risk factors suggest syphilis exposure. Early diagnosis matters because syphilis is treatable, and untreated infection can lead to serious complications affecting the brain, nerves, eyes, and heart, and it can also be passed to a baby during pregnancy.

Common reasons a clinician orders VDRL/RPR include:

Symptoms that could fit syphilis:

• A painless sore (chancre) on the genitals, anus, or mouth

• A body rash (often on palms/soles), fever, swollen lymph nodes, sore throat, fatigue

• Patchy hair loss, mouth/genital lesions

• Neurologic or eye symptoms in some cases (headache, confusion, vision changes), especially if syphilis is suspected

Sexual health screening and exposure concerns:

• New or multiple sexual partners, unprotected sex, or a partner diagnosed with syphilis or another STI

• Men who have sex with men (MSM) or anyone in a community with higher STI prevalence

• Symptoms of another STI (people with one STI may be at higher risk for others)

Pregnancy and newborn health:

• Routine prenatal screening (often early in pregnancy, and again later if risk is higher) to prevent congenital syphilis

Follow-up and monitoring:

• Confirming prior positive results, establishing a baseline titer before treatment, and checking that titers decline appropriately after treatment

• Evaluating possible reinfection if titers rise again or symptoms return

• Syphilis (primary, secondary, latent, and tertiary stages)
• Neurosyphilis (syphilis involving the brain or nervous system)
• Ocular syphilis (syphilis affecting the eyes)
• Congenital syphilis (infection passed from parent to baby during pregnancy)
• Other sexually transmitted infections (co-testing is common, such as HIV, gonorrhea, and chlamydia)

• Sexual health screening and early detection of syphilis
• Reducing the risk of transmitting syphilis to sexual partners
• Safer pregnancy planning and prenatal care (preventing congenital syphilis)
• Monitoring treatment effectiveness and ensuring infection is resolving (tracking RPR/VDRL titers)
• Overall STI risk assessment and prevention planning (including partner notification and follow-up testing)