Sexually Transmitted Infection (STI) Tests
Reviewed
Also called: STD screening, STI screening, STD testing, Sexually transmitted disease tests
STI tests detect infections passed through sexual contact, including chlamydia, gonorrhea, herpes, HIV, and HPV. Testing can identify infections even without symptoms, allowing treatment and preventing spread.
Specimen: Blood, urine, swab (vaginal, cervical, penile, urethral, oral, anal), or cerebrospinal fluid (lumbar puncture)
Why this test may be ordered
- To check for STIs when you have symptoms such as painful urination, discharge, sores, or itching
- To screen for STIs if you are sexually active and at higher risk (e.g., under 25, multiple partners, men who have sex with men, pregnant)
- To detect infections that may not cause symptoms but can lead to long-term health problems if untreated
- To confirm infection after a partner is diagnosed with an STI
Preparation and collection
No special preparation for a blood test. Women may need to avoid douches and vaginal creams for 24 hours before a urine or swab test. You may need to empty your bladder before a lumbar puncture. Your provider will give specific instructions.
Blood sample from a vein in your arm; urine sample in a sterile cup; swab from the infection site (vagina, cervix, penis, urethra, mouth, or anus); or lumbar puncture (spinal tap) for advanced syphilis or herpes affecting the brain or spinal cord.
Blood test: slight pain or bruising at needle site, usually resolves quickly. Urine or swab tests: no known risks. Lumbar puncture: possible back pain or headache lasting hours to a week or more; your provider can suggest treatment for pain.
Understanding results
Your test result will show whether an STI was detected. Discuss the result with your healthcare provider to understand what it means for your health and next steps.
- Positive: An STI was detected in your sample. Limitation: False positives can occur; confirmatory testing may be needed. A positive result does not indicate which specific STI without further testing. Next step: Follow your provider's treatment plan exactly as prescribed. Inform your sexual partners so they can get tested and treated if needed.
- Negative: No STI was detected in your sample. Limitation: False negatives can occur if tested too soon after exposure (window period) or if the sample was not collected from the infection site. A negative result does not rule out all STIs. Next step: Continue preventive measures (e.g., condom use, vaccination). If you have symptoms or ongoing risk, discuss repeat testing with your provider.
- STI tests may not detect infections during the window period (time between exposure and when the test can find the infection).
- False-positive and false-negative results are possible; your provider may recommend confirmatory testing.
- Not all STIs are included in a single test; you may need multiple tests based on your risk factors.
- At-home test results should be discussed with a provider for confirmation and treatment.
What to do next
If your result is positive, take all prescribed medicine as directed and notify your sexual partners. If negative but you have symptoms or ongoing risk, talk to your provider about repeat testing. Continue using condoms and consider vaccination for HPV and hepatitis B.
- Which STIs am I being tested for, and why?
- How long after exposure should I wait to be tested for accurate results?
- What should I do if my test result is positive?
- Do I need to be tested again in the future?
- Can I get an STI even if my partner has no symptoms?
Evidence source
U.S. National Library of Medicine: Sexually Transmitted Infection (STI) Tests