An STI test typically involves one or more of three simple sample types: a urine sample, a swab, or a blood draw. Which combination you get depends on what infections are being checked and where on your body they might be. The whole process is usually quick, and most of it you can do yourself.
What Infections Are Tested and How
There is no single test that checks for every STI at once. Different infections require different sample types, so a full screening usually combines methods.
- Urine sample: Used to detect chlamydia and gonorrhea. This is the most common test for these two infections, especially in men.
- Swabs: Used for chlamydia, gonorrhea, and sometimes herpes or HPV. Swabs can be taken from the vagina, throat, or rectum depending on the type of sexual contact you’ve had.
- Blood draw: Used for HIV, syphilis, hepatitis B, and sometimes herpes. A small sample is taken from a vein in your arm, just like any routine blood test.
Your provider will ask about your sexual history to decide which tests and which body sites to include. For men who have sex with men, the CDC recommends annual screening at all sites of contact, including the urethra, rectum, and throat, regardless of condom use. For women, rectal and throat testing may be added based on sexual behaviors. This isn’t about judgment. Infections at these sites often cause zero symptoms, so testing is the only way to catch them.
What the Urine Test Is Like
If you’re being tested for chlamydia or gonorrhea through urine, you’ll pee into a small cup. The key detail: you need the first part of the stream, not a midstream sample. That initial flow picks up infected cells from the urethra, which is exactly what the lab needs to detect the infection. Fill the cup about one-third full, then pass the rest into the toilet.
You should wait at least 20 minutes after your last trip to the bathroom before collecting the sample. Don’t clean or wipe your genitals beforehand. An early morning sample isn’t required, and you can test at any time of day as long as you haven’t urinated too recently.
What Happens With Swabs
Swab tests sound more intimidating than they are. For vaginal swabs, many clinics now let you collect the sample yourself in a private room. You insert a soft swab about an inch, rotate it gently for about 15 seconds, then place it in a transport tube. That’s it. Self-collected vaginal swabs are highly accurate, detecting chlamydia with 92% sensitivity compared to clinician-collected samples.
Throat swabs work like a strep test. A swab is rubbed against the back of your throat for a few seconds. Rectal swabs involve inserting a small swab just inside the anus and rotating it briefly. Both of these can also be self-collected in many clinics, and studies show self-collected rectal swabs match clinician-collected ones closely, with about 88% sensitivity for chlamydia and gonorrhea.
If a clinician performs a vaginal swab, it may be done during a pelvic exam with a speculum, similar to a Pap smear. This is less common now for routine chlamydia and gonorrhea screening since self-collection works so well.
What the Blood Draw Covers
A standard blood draw checks for infections that travel through the bloodstream rather than living on a specific body surface. HIV, syphilis, and hepatitis B all require blood testing. Herpes blood tests exist but aren’t part of routine screening for most people, since the results can be hard to interpret without symptoms.
The blood draw itself is routine: a needle in your arm, a small vial or two, and a bandage. Some clinics offer rapid HIV testing using a finger prick or oral cheek swab, which can return a preliminary result in about 20 minutes. A standard lab-processed blood test is more sensitive, though, especially for recent exposures.
When to Test After Exposure
Testing too soon after a potential exposure can produce a false negative. Each infection has a detection window, which is the minimum time needed for the test to pick it up reliably.
- Chlamydia and gonorrhea: Detectable within one week in most cases. Waiting two weeks catches nearly all infections.
- HIV (blood test): A lab-based blood test that looks for both the virus and antibodies can detect most infections within two weeks, and catches almost all by six weeks. An oral swab test takes longer, typically reliable at one month and most accurate at three months.
- Syphilis: Blood tests pick up most cases at one month, with three months needed to catch nearly all.
If you’re testing after a specific exposure and it’s only been a few days, your provider may suggest waiting or doing an initial test now with a follow-up later to cover the window period.
How Long Results Take
Most STI test results come back within five to ten days from a standard lab. Some clinics offer rapid HIV tests with same-day results, but the majority of tests (chlamydia, gonorrhea, syphilis, hepatitis) go through a laboratory and take several business days. Your clinic will let you know how you’ll receive results, whether by phone, patient portal, or follow-up visit.
What Happens If a Test Is Positive
A positive result for chlamydia or gonorrhea means a course of antibiotics. These infections are curable, and treatment is straightforward. You’ll also be asked to notify recent sexual partners so they can get tested and treated. This matters because reinfection is common if a partner carries the infection without knowing. Even after both you and your partner complete treatment, the CDC recommends retesting in three months to confirm the infection is gone.
For infections detected by blood test, the follow-up depends on what’s found. Syphilis is also curable with antibiotics. HIV requires ongoing treatment but is highly manageable with modern medication. Hepatitis B may resolve on its own or may need long-term management depending on the type of infection. In every case, your provider will walk you through specific next steps based on your result.
Self-Collection and At-Home Testing
Self-collection has become increasingly common, both in clinics and through mail-order test kits. At-home kits typically include swabs, a urine cup, and sometimes a finger-prick blood collection device. You collect your own samples following the included instructions, then mail everything to a lab in a prepaid package.
The accuracy of self-collected samples is reassuringly close to clinician-collected ones. For chlamydia, self-collected vaginal swabs achieve 92% sensitivity. Male urine self-samples detect chlamydia with 88% sensitivity and gonorrhea with 92% sensitivity. The one area where self-collection is slightly less reliable is urine testing in women for gonorrhea, where sensitivity drops to about 79%, which is why vaginal swabs are generally preferred for women when possible.