What is the Syphilis PCR (Chancre) Test?

The Syphilis PCR (Chancre) test is a molecular test that detects the DNA of Treponema pallidum, the bacterium that causes syphilis, directly from a chancre (syphilitic sore). A swab is taken from the lesion and analysed using PCR technology, which is highly sensitive and specific.

Unlike blood tests that rely on antibody formation, PCR identifies the infection at the site of active disease. This makes it particularly valuable in very early syphilis, when blood tests may still be negative.

The test is most effective when a fresh, untreated chancre is present.

Why do I need a Syphilis PCR test?

Syphilis can be difficult to diagnose in its early stages because symptoms may be mild and blood antibodies may not yet be detectable. Testing the chancre itself provides direct confirmation of infection.

You may need this test if you have:

• A painless genital, anal, or oral ulcer
• A sore that appeared after sexual contact
• A lesion that does not heal within 1–3 weeks
• Suspected primary syphilis
• Negative or inconclusive blood tests with a visible chancre
• Recent high-risk sexual exposure with a lesion present

Early detection is crucial to prevent progression to secondary or latent syphilis, which can cause serious long-term complications.

Benefits of the test

1. Direct detection at the source
   Identifies the bacterium directly from the chancre.
2. Highly sensitive early diagnosis
   Detects infection before antibodies develop.
3. Greater accuracy than blood tests in early disease
   Reduces false-negative results in primary syphilis.
4. Rapid molecular confirmation
   PCR provides precise organism identification.
5. Useful when blood results are unclear
   Clarifies diagnosis in early or atypical cases.
6. Supports prompt clinical decision-making
   Enables earlier intervention and follow-up.
7. Reduces onward transmission risk
   Early diagnosis helps limit spread to partners.
8. Targeted testing for visible lesions
   Ideal when a chancre is present and accessible.

Step-by-step: How we offer testing

Clinic-based testing (UK-wide)

• Choose your nearest UK clinic
• Attend your appointment
• A clinician swabs the chancre lesion
• Sample is sent to the laboratory
• Results are issued once analysis is complete

Home or hotel visit (+£60, UK-wide)

• Book a mobile clinician
• Chancre swab taken at your home or hotel
• No clinic visit required
• Sample securely transported to the laboratory

Your results explained

Not detected (negative)

• No Treponema pallidum DNA identified
• UK standard: Not detected
• Suggests the lesion is not due to syphilis or sampling was too late

Low-level detection

• Small quantities of bacterial DNA detected
• UK standard: Low positive / equivocal
• May reflect very early infection or partial healing

Detected (positive)

• Treponema pallidum DNA identified
• UK standard: Detected
• Confirms active syphilis infection at the lesion site