STD Testing by Urine PCR: 7 Infections, No Swab

Dernière mise à jour : 15 août 2026

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A steady stream of patients come to me for advice after a high-risk sexual encounter. Most are men, largely because men tend to develop symptoms while women often have none at all — or only something vague like an unusual odour or mild itching. That difference matters more than it sounds: it means a woman can carry and pass on an infection without ever suspecting it.

Chlamydia and gonorrhoea are the two commonest sexually transmitted infections in the world, with over 200 million new cases a year. They are transmitted through vaginal, oral and rectal contact. In men, urethral discharge and pain on passing urine typically appear 3–14 days after exposure.

Why the test changed

Testing used to mean a urethral swab — a cotton tip inserted about 4 cm into the urethra, uncomfortable enough that it discouraged plenty of men from being tested at all, and only around 50% accurate depending on who took it.

Today the standard is NAAT (nucleic acid amplification testing) using PCR, which finds the organism’s genetic material in a simple morning urine sample and reaches up to 98% accuracy. No instrument goes anywhere near the urethra. If the swab is what has been putting you off, that obstacle no longer exists.

The 7 infections detected in one urine sample

• Chlamydia trachomatis
• Neisseria gonorrhoeae
• Trichomonas vaginalis
• Mycoplasma genitalium
• Mycoplasma hominis
• Ureaplasma urealyticum
• Ureaplasma parvum

What this test does ne pas cover

This is the part that matters most, and it is the reason a urine PCR panel is not the same thing as “a full STD check”. The panel above does not detect HIV, syphilis, genital herpes or HPV. Those need separate testing — blood tests for syphilis and HIV, and clinical assessment for herpes and warts.

A clear urine PCR result after a high-risk encounter is genuinely reassuring about seven infections. It is not a clean bill of health, and treating it as one is the mistake I most want to prevent. Decide what to test for with a doctor, based on what actually happened.

When to take the test

Timing changes the result. Testing too soon after exposure can give a negative even when infection is present, because there is not yet enough genetic material to detect — the window period. For chlamydia and gonorrhoea, testing is generally reliable from about 1–2 weeks after exposure; the blood-borne infections above have their own, longer windows.

Two practical points: hold your urine for at least an hour before giving the sample, since freshly flushed urine dilutes what the test is looking for; and if you have symptoms now, do not wait for a window period to pass before being seen.

The good news, stated accurately

All seven infections on this panel are bacterial or parasitic, and all of them are curable with the right antibiotic. That is a genuinely encouraging thing to be able to say. It applies to this panel — HIV, herpes and HPV are managed rather than cured, which is another reason to know which test you have had.

Two things make the difference between treatment working and the same infection returning a month later: finishing the full course, and your partner being treated at the same time. Reinfection from an untreated partner is the commonest reason a cured infection reappears.

Si vous avez eu un rapport sexuel à haut risque ou si vous souhaitez un dépistage IST confidentiel et indolore par test d'urine PCR multiplex, le Dr Soarawee Weerasopone propose des consultations spécialisées au siège de l'hôpital de Bangkok. Prendre rendez-vous. Les rendez-vous à l'hôpital Samitivej Sriracha peuvent être pris en appelant le service d'urologie au 088-022-1445.

Questions fréquemment posées sur les tests PCR d'IST sur urine

Avis de non-responsabilité : This content is written and reviewed by Dr. Soarawee Weerasopone, a board-certified urologist at Bangkok Hospital Headquarters. It is intended for educational purposes only and does not constitute medical advice. No medical advice, diagnosis or prescription is provided through personal messaging channels. Always consult a qualified healthcare professional before starting any medical treatment.