Clin Microbiol Infect
Missed infections: why single-site STI screening may be failing women
Clinical takeaway: Consider multisite (oral, anal, vaginal) screening for Chlamydia trachomatis and Neisseria gonorrhoeae in women undergoing STI testing, regardless of reported sexual practices or symptoms.
Extragenital STIs are often asymptomatic and can sustain transmission—missing them may delay treatment and increase complications, including infertility.
A multicenter prospective SIST'RS study of 1,498 non–sex worker women in France found that systematic three-site screening significantly outperformed traditional vaginal-only testing for detecting Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG).
Detection rates rose from 10.1% (151/1492) with vaginal testing alone to 13.8% (179/1295) with combined oral, anal, and vaginal sampling (p<0.001). For CT, detection increased from 9.2% to 12.4% (p<0.001), and for NG from 1.4% to 2.4% (p=0.008). Among participants who completed all three tests, prevalence rose from 10.0% to 12.0%, identifying 25 additional infections.
Notably, 16.4% of infections were located exclusively at extragenital sites (oral and/or anal) without vaginal involvement—meaning they would have been entirely missed by single-site screening.
Symptoms and reported sexual behaviors proved unreliable predictors: only 24% of infected women reported any symptoms, and anal infections occurred at similar rates regardless of reported anal sex. Oral and anal infections were largely asymptomatic (<10%), reinforcing the limitations of symptom-driven testing.
“Multisite testing should be considered for women to ensure accurate diagnosis and treatment,” the authors conclude, emphasizing that reliance on sexual history alone risks underdiagnosis.
Overall, the findings challenge current screening practices and suggest broader multisite testing could play a key role in reducing missed infections and curbing STI transmission.
Source: Prazuck T, et al; SIST’RS Study Group. (2026, May). Clin Microbiol Infect. Systematic three-site vs. classical single-site screening for Chlamydia trachomatis and Neisseria gonorrhoeae infections in non-sex worker women: the multicentric Sexually Infections Still Transmitted by Remote Sites (SIST'RS) study