STI Screening: Which Tests, When, and for Whom?

The most dangerous feature of sexually transmitted infections fits in one word: silence. HIV, syphilis, chlamydia, HPV, hepatitis B and C — most cause no symptom for months, sometimes years, while remaining transmissible and progressing. Screening is therefore the only way to know. Here is the practical guide, as we apply it in our medical analysis laboratory in Tangier: which test for which infection, when, and how it works.

Which test for which infection?

• HIV — a blood test (serology); reliable about 6 weeks after the risk with current tests. Our article: the HIV test in practice;
• syphilis — a blood test (serology); see our article syphilis: the simple test;
• chlamydia and mycoplasma — PCR on first-catch urine or a local swab; our article: chlamydia, the silent STI;
• HPV — PCR with genotyping in women, as part of cervical screening; our article: positive HPV test;
• hepatitis B and C — blood test (serology B, serology C); for followed patients, the viral load takes over.

Your doctor can prescribe a grouped STI panel — often the simplest: one visit to the laboratory covers the essentials.

When to get screened?

The right reflex in four situations: after unprotected sex or a condom accident; at the start of a new relationship, ideally both partners; facing any symptom however discreet (burning, discharge, sore, swollen node); and during pregnancy, where several screenings are part of follow-up. Beware of testing too early: each infection has its detection window (from days for chlamydia PCR to weeks for HIV and syphilis). After a dated risk, the doctor or the laboratory tells you the right moment — sometimes an immediate first test then a control.

How does it work at the laboratory?

No appointment needed, with a prescription — and in full confidentiality: results are given to you alone. One blood draw covers HIV, syphilis and hepatitis; first-catch urine or a local swab covers chlamydia and mycoplasma. If a result comes back positive, two reflexes: see your doctor (most STIs treat very well, and earlier is better), and inform partner(s) so they get tested — that is what breaks the chain of transmission.

Frequently asked questions

I have no symptoms — do I need a test?

That is precisely the heart of the problem: most STIs are silent. The absence of symptoms says nothing — only the test informs. After a risk or at the start of a relationship, screening is the right reflex even when feeling fine.

How long after a risky encounter should I test?

Each infection has its window: on the order of one to two weeks for chlamydia by PCR, several weeks for HIV and syphilis. The right schedule — sometimes an immediate test then a control — is set with the doctor according to the date of the risk.

Is screening confidential?

Yes, fully: medical secrecy applies and results are handed to you alone.

Do I need to fast?

No — no STI test requires fasting. For chlamydia on urine, not urinating in the previous 2 hours is the only instruction.

What if a test is positive?

See your doctor promptly: most STIs treat simply, all the better when early. Informing partners so they get tested and treated too is part of the treatment — otherwise the infection circulates in a loop.

How often should I get screened?

No single rule: after each risk, at each new relationship, and regularly with multiple partners. Your doctor can set a rhythm suited to your situation.