What is the STI Symptomatic Lesion PCR Swab Test?

The STI Symptomatic Lesion PCR Swab Test is a molecular test that detects the genetic material (DNA/RNA) of sexually transmitted infections directly from a visible lesion, sore, blister, or ulcer. A swab is taken from the affected area and analysed using PCR (polymerase chain reaction), a highly sensitive laboratory technique.

This test is particularly effective because it samples the exact site of symptoms, increasing diagnostic accuracy compared to blood or urine testing alone. PCR can identify infections even at very low levels, often before antibodies have formed.

It is commonly used to detect infections such as herpes simplex virus (HSV-1, HSV-2), syphilis (Treponema pallidum), chancroid, and other lesion-associated STIs, depending on the PCR panel used.

Why do I need a test for STI lesions?

If you have visible genital, oral, or anal lesions, testing the lesion itself is the most direct and reliable way to identify the cause. Many STIs can look similar clinically, and symptoms alone are not enough to determine the infection.

You may need this test if you experience:

• Painful or painless sores or ulcers
• Blisters or open lesions on genitals, anus, or mouth
• Tingling, burning, or itching before lesions appear
• Lesions that do not heal or recur
• Discharge or crusting from a sore
• Recent sexual contact with a new or high-risk partner

Early and accurate identification helps guide appropriate medical follow-up, reduces the risk of transmission to others, and prevents unnecessary anxiety or incorrect treatment.

Benefits of the test

1. High diagnostic accuracy
   PCR directly detects the pathogen’s genetic material, making it one of the most sensitive STI testing methods available.
2. Targeted testing at the source
   Sampling the lesion itself increases the likelihood of identifying the exact cause of symptoms.
3. Early detection
   Infections can be detected even before antibodies are present in the blood.
4. Fast turnaround times
   PCR analysis provides quicker results compared to culture-based methods.
5. Differentiates similar symptoms
   Helps distinguish between infections that cause similar-looking lesions.
6. Reduces unnecessary treatment
   Accurate diagnosis prevents inappropriate or ineffective medication use.
7. Confidential and discreet
   Private testing without the need for GP referral.
8. Supports partner notification and care
   Clear results allow informed decisions about testing and follow-up for partners.

Step-by-step: How we offer testing

Clinic appointment (UK-wide)

• Choose your nearest UK clinic
• Attend your appointment
• A clinician takes a swab directly from the lesion
• Sample is sent to the laboratory
• Results are issued once analysis is complete

Home or hotel visit (+£60, UK-wide)

• Book a mobile phlebotomist or clinician
• A professional visits your home or hotel
• Lesion swab is taken discreetly
• No need to travel or leave your accommodation
• Sample is securely transported to the lab

Your results explained

Not detected (negative)

• No STI genetic material was found in the lesion sample
• This suggests the symptoms are not caused by the tested infections
• UK standard: Result reported as Not Detected

Detected (positive)

• Genetic material of a specific STI has been identified
• Confirms an active infection at the lesion site
• UK standard: Result reported as Detected with organism identified

Inconclusive or low-level detection

• Very small amounts of genetic material detected or sample limitations
• Repeat testing or additional tests may be advised
• UK standard: Result reported as Equivocal or Low-level Detected