Background Chlamydia trachomatis is the most commonly diagnosed STI in the UK. While men-who-have-sex-with-men are known to be at-risk of rectal chlamydia infection (ReCT), the prevalence and risk-factors in women are incompletely-understood. This may have important implications for testing and treatment approaches since azithromycin and doxycycline are considered first-line regimens for uncomplicated urogenital infections, whereas doxycycline is the preferred treatment for ReCT.

Objectives Undertake a systematic review to: 1) calculate ReCT positivity (number ReCT positive/number tested) among women in different testing settings; 2) determine the proportion of women diagnosed with ReCT with: a) concurrent urogenital infections and; b) a history of anal-intercourse.

Methods Medline, Embase, CINAHL, PsychINFO and the Cochrane Database were searched for articles published January 1997-September 2015. Studies reporting ReCT positivity in women aged ≥15 years in high-income countries were included and relevant data extracted.

Results Fifteen studies were included (14 among women attending sexual health services). Populations tested varied e.g. 4/15 studies included only women with a history of anal-intercourse. Among all studies, ReCT positivity ranged from 0.5%–77% (median 13%). Among women with ReCT, 7%–100% had a concurrent urogenital infection; 16%–100% reported anal-intercourse (where data were available; Table 1)

Conclusion ReCT infections have been found in a substantial proportion of women in the populations tested. In these studies, urogenital testing alone would have missed up to 31% of chlamydia infections. Further work to establish need, criteria and feasibility for routine ReCT testing in women is needed to ensure chlamydia infections are not missed or inadequately treated.