Background The proportion of infectious urethritis associated with oral sex is unknown.

Methods We conducted a retrospective study of MSM diagnosed with symptomatic urethritis attending an STD Clinic between 2001–2010. We categorised men according to their urethral exposures in the previous 60 days: (1) only insertive oral sex and no insertive anal sex (IOS); (2) only protected insertive anal intercourse and insertive oral sex (PIAI); (3) unprotected insertive anal intercourse with or without oral sex (UIAI); (4) no insertive sex (oral or anal). We calculated the proportion of urethritis cases by groups as a minimum estimate of the proportion of cases attributable to oral sex.

Results Between 2001–2010, 4,091 MSM were diagnosed with urethritis, had complete records for categorization, and were included in this analysis. Men reported the following urethral exposures: 13% IOS, 21% PIAI, 65% UIAI, and < 1% no urethral exposure. Among 1,506 cases of gonococcal urethritis, 72% occurred among men reporting UIAI and 27.8% (95% CI 25.5% - 30.1%) occurred in MSM reporting oral sex as their only urethral exposure (9.4% IOS and 18.4% PIAI) in the last 60 days. Of the 787 cases of chlamydia urethritis, 71% were in men reporting UIAI, 8.8% IOS and 19.6% PIAI, making 28.3% (95% CI 25.2% - 31.6%) of chlamydial urethritis cases attributable to oral exposure in the prior 60 days. Among 1,999 cases of NGNCU, UIAI accounted for 59% of cases; oral sex accounted for 43.1% (95% CI 40.9% - 45.3%). 17% and 24% of NGNCU cases occurred in men reporting IOS and PIAI, respectively.

Conclusion While usually considered a safer sexual practise, our findings suggest that a large proportion of all cases of urethritis are attributable to insertive oral sex. These findings highlight the importance of screening the oropharynx and counselling MSM about the risks of oral sex.