After a sexual assault, STD testing usually starts with a baseline visit — a urine cup or self-collected swab for chlamydia, gonorrhea, and trichomoniasis, plus a blood draw for HIV, syphilis, and hepatitis. Because infections take time to show up, you'll typically repeat some tests weeks later. Forensic evidence collection and medical care are separate; you can have either or both.
| Item | Days after exposure |
|---|---|
| Chlamydia / gonorrhea (NAAT) | ~14 |
| HIV — NAT | 10–33 |
| HIV — antigen/antibody | 18–45 |
| HIV — rapid antibody | 23–90 |
The essentials
Two things happen when you seek care after an assault, and it helps to keep them apart. One is the forensic exam — collecting evidence for a possible legal case. The other is your medical care: testing, preventive medication, and follow-up to protect your health. You can choose one without the other. Declining a forensic kit does not stop you from getting tested or treated, and getting medical care does not commit you to reporting anything to police.
On the medical side, the survivor-specific approach has a logic to it. Clinicians often offer presumptive treatment — preventive antibiotics and, where appropriate, HIV prevention — at the first visit, before any test result is back. The wait for a reliable test can run weeks, and treating up front spares you a return trip and the anxiety of an uncertain interval. A baseline test at that first visit documents your status near the time of the assault, and a follow-up test later catches infections that hadn't yet become detectable.
Many STIs cause no symptoms at all, so how you feel after an assault tells you nothing reliable about whether an infection was transmitted. Testing establishes your status, so screening is the standard even when nothing feels wrong USPSTF.
How STD testing works for survivors
The mechanics of the tests are the same ones used in any STI screening. What's tailored for survivors is the timing and the option to treat preventively. Each test looks for something specific and becomes trustworthy at its own point.
What the tests are and what they feel like
Most bacterial and parasitic infections are caught from a single, low-effort sample. For chlamydia, gonorrhea, and trichomoniasis, that's a urine cup or a self-collected swab run as a NAAT (nucleic acid amplification test). For HIV, syphilis, and hepatitis, it's a quick blood draw. In practice you're in the chair for minutes, and results come back in a day or a few.
NAATs are the most sensitive method for chlamydia and gonorrhea, so they're recommended over older culture-based approaches. Modern NAATs are highly accurate, with specificity around 99 percent, so false alarms are rare CDC.
Why a baseline test matters
A test done at the first visit can't catch an infection that's only days old, and that's expected behavior rather than a failed test. The baseline records whether you already carried an infection before the assault, which matters medically and, if you pursue a case, legally. A negative baseline followed by a later positive helps clarify when an infection was likely acquired.
The window period and follow-up testing
Every test has a window period — the gap between exposure and when the infection becomes detectable. Test inside that window and you can get a falsely reassuring negative, because the infection hasn't built up enough material to register yet. This is the most common cause of a false negative, so a too-early negative should be repeated rather than trusted. Knowing when to test after exposure is what makes follow-up testing worth doing.
For chlamydia and gonorrhea, a NAAT is generally reliable about two weeks after exposure; if your baseline was sooner, retesting around that mark is reasonable. HIV is more nuanced because the window depends on the test used.
| HIV test type | Earliest reliable detection after exposure |
|---|---|
| Nucleic acid test (NAT) | About 10–33 days |
| Antigen/antibody lab test | About 18–45 days |
| Rapid antibody test | About 23–90 days |
A negative HIV result at your baseline visit doesn't close the question. Your clinician will set a follow-up based on which test was used and whether HIV prevention was started CDC, HIV Testing.
How false positives are prevented
Because a positive HIV or syphilis result carries real weight, both use a two-step process: an initial screening test, then a different confirmatory test, and the result isn't final until the confirmatory step agrees. A reactive rapid HIV test is a preliminary result that has to be confirmed with a follow-up lab test before anyone calls it a diagnosis CDC, 2024. If you're handed a reactive rapid result in a stressful moment, that's the start of confirmation, not the end of the story.
Practical details: cost, access, and where to go
You're rarely far from low-cost testing. The US has roughly 16,000 federally-funded community health centers and about 4,200 Title X family-planning clinics, alongside tens of thousands of other public STI clinics, most offering free or income-based sliding-scale care HRSA. Doctors' offices, health departments, and Planned Parenthood all test as well, and at-home or self-collection kits exist if a clinic visit feels like too much right now.
- Hospital emergency departments and many clinics can do a forensic exam and baseline testing in the same visit — ask for a SANE (sexual assault nurse examiner) if one is available.
- Title X and federally-funded health centers bill on income, so cost shouldn't be the reason you skip care.
- If you use an at-home kit, mind the window period; testing too early just means you'll need to repeat it.
- You can get tested without filing a police report; medical care is yours to access regardless of what you decide about reporting.
A common, costly mistake is treating one early negative as the final word. The infection may simply not have been detectable yet. Keep the follow-up appointment your clinician schedules. That visit, not the first one, is often when a quietly transmitted infection actually shows up.
What this article does not cover
This is the testing-and-timing picture, not a treatment manual. Specific antibiotic and HIV-prevention regimens, the forensic-exam protocol step by step, and counseling or advocacy resources are handled by survivor-care teams and other pages. If you're navigating identity-specific concerns about exams and anatomy-based screening, see std testing for trans & nonbinary people for guidance written for those situations.
When to see a clinician
Seek care as soon as you reasonably can, ideally within a few days. Time-sensitive prevention — HIV post-exposure prophylaxis and emergency contraception — works best when started early, and forensic evidence is most useful when collected soon after the assault. Go sooner if you have pelvic or genital pain, fever, unusual discharge, bleeding, or any injury that needs attention. Even if days or weeks have passed, it is never too late to get a baseline test and arrange follow-up; testing later is far better than not testing at all.