Who needs STI screening, how often, and whether home tests are accurate
US guidelines recommend routine chlamydia and gonorrhea screening for sexually active women under 25 and older women at higher risk. Self-collected swabs match clinician-collected ones closely.
Two questions dominate practical decisions about sexually transmitted infection testing: who should be screened routinely, and whether the at-home kits now sold widely are trustworthy. On the first, the US Preventive Services Task Force recommends screening for chlamydia and gonorrhea in all sexually active women 24 or younger, and in women 25 or older who are at increased risk of infection [s1]. On the second, a meta-analysis found that samples people collect themselves are about as accurate as those a clinician collects [s2].
Both answers come with important boundaries — around who the recommendation does and does not cover, and around what "accurate" means for a screening test.
Who the guideline says to screen, and how often
The Task Force gives its chlamydia and gonorrhea screening recommendation a "B" grade — meaning it recommends the service — for sexually active women 24 years or younger, and for women 25 or older "who are at increased risk for infection" [s1]. Increased risk is defined in familiar terms: having a new sex partner, more than one partner, or a partner who has a sexually transmitted infection [s1]. The recommendation applies to sexually active women, including those who are pregnant [s1].
The guideline is equally clear about where the evidence runs out. For screening men, it concludes "the current evidence is insufficient to assess the balance of benefits and harms" — an "I" statement, meaning no recommendation either way, not a recommendation against [s1]. That gap reflects a lack of trials in men, not proof that screening men is useless.
The recommendation is risk-based rather than calendar-based, which is the source of most confusion about "how often." Age under 25 plus sexual activity is itself the trigger for routine screening; over 25, it is the presence of ongoing risk factors that determines whether and how frequently to test [s1]. Because chlamydia and gonorrhea are frequently symptomless, the rationale for screening the young and the higher-risk is that infections would otherwise go undetected until they cause complications [s1].
Whether at-home and self-collected tests are accurate
The rise of mail-order and pharmacy STI kits raises a fair question: is a sample you collect yourself as good as one a clinician takes? A systematic review and meta-analysis compared self-collected against clinician-collected specimens for chlamydia and gonorrhea, analysing accuracy by specimen type [s2].
Self-collected vaginal swabs performed best. Compared with a clinician-collected cervical swab, self-collected vaginal swabs for chlamydia had a sensitivity of 92% (95% CI 87-95) and a specificity of 98% (95% CI 97-99) — the highest of the specimen types examined [s2]. Self-collected urine was slightly less sensitive for chlamydia at 87% (95% CI 81-91), with high specificity of 99% [s2]. For gonorrhea, self-collected urine in men had a sensitivity of 92% (95% CI 83-97) and specificity of 99% [s2]. The review concluded the accuracy of vaginal self-collected swabs "supports the use of vaginal swab as the recommended specimen of choice in home-based screening for chlamydia and gonorrhea" [s2].
Reading those accuracy numbers correctly
A sensitivity of 87-92% is high, but it is not 100%, and that matters for how a home test should be read. Sensitivity is the share of true infections the test catches; a self-collected urine sample missing around 13% of chlamydia cases means a negative home result is reassuring but not a guarantee, particularly after a recent exposure [s2]. Specificity near 98-99% means false positives are uncommon, so a positive result is likely real and warrants confirmation and treatment [s2].
The evidence also covers only the collection step and only chlamydia and gonorrhea — not every infection a "full panel" home kit claims to detect, and not the quality of any particular commercial product's laboratory processing [s2]. The kits' value lies in removing a barrier to getting tested at all, using a sampling method the evidence supports, not in replacing clinical assessment when symptoms are present.
Put together, the guidance is coherent: routine screening is aimed at sexually active women under 25 and at older women with ongoing risk, self-collected vaginal swabs are an accurate way to obtain the sample, and a home test is a screen — a strong reason to seek care on a positive, and no reason to ignore symptoms on a negative [s1] [s2].
This article is informational and is not medical advice. Decisions about STI screening, and the interpretation of any test result, should involve a clinician.
Sources
- Screening for Chlamydia and Gonorrhea: US Preventive Services Task Force Recommendation Statement — US Preventive Services Task Force, 2021-09-14
- Self-Collected versus Clinician-Collected Sampling for Chlamydia and Gonorrhea Screening: A Systematic Review and Meta-Analysis — PLOS One, 2015-07-13
Sources
- Screening for Chlamydia and Gonorrhea: US Preventive Services Task Force Recommendation Statement — US Preventive Services Task Force , September 14, 2021
- Self-Collected versus Clinician-Collected Sampling for Chlamydia and Gonorrhea Screening: A Systematic Review and Meta-Analysis — PLOS One , July 13, 2015
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