How do rates of fecal incontinence differ between populations with and without history of long-term anal sex?
Executive summary
Population studies and large surveys consistently find higher reported rates of fecal incontinence (FI) among people who report receptive anal intercourse compared with those who do not, but the effect sizes vary by sex, study design and how anal sex and FI are measured [1] [2] [3]. The association remains after statistical adjustment in some national data sets, yet all studies are observational and limited by self-report, cross‑sectional designs and potential confounding [1] [4].
1. The evidence in numbers: what the surveys report
A nationally representative U.S. survey (NHANES 2009–2010) found that women reporting any lifetime receptive anal intercourse had FI at a rate of about 9.9% versus 7.4% in women who did not report anal intercourse, while men reporting anal intercourse had substantially higher crude rates (about 11.6% vs. 5.3% in men) according to media summaries of the same analysis [2] [5] [1]. A very large convenience survey of men who have sex with men (MSM) in France reported FI prevalences of 12.7% in men reporting receptive anal intercourse several times per week versus 5.7% in those not engaging in RAI [6] [4]. Smaller clinical and registry‑based samples of women report FI prevalences around 15% in cohorts with anal penetrative intercourse, though sampling frames vary [7] [8].
2. The strength of the association after adjustment
In the NHANES analysis, receptive anal intercourse remained associated with higher odds of FI after multivariable adjustment: prevalence odds ratio (POR) ≈1.5 for women (95% CI 1.0–2.0) and POR ≈2.8 for men (95% CI 1.6–5.0), indicating a stronger adjusted association in men in that data set [1]. The large MSM survey describes dose‑related patterns—more frequent RAI and specific practices (chemsex, fisting, BDSM) associate with higher FI rates—but its nonrandom sampling and one‑month FI window limit causal inference [4] [6].
3. Mechanisms proposed and physiological data
Authors and commentators propose that repeated anal stretching or trauma from penetrative practices could reduce anal sphincter resting pressure or cause minor sphincter injury, producing urgency or leakage symptoms; studies have reported lower manometry pressures in men reporting anal intercourse and more urgency-type symptoms in some cohorts [9] [5]. Narrative reviews of pelvic‑floor effects summarize heterogeneous evidence that consensual anal penetrative intercourse can be a risk factor for anodyspareunia and FI in both sexes, particularly when practices are frequent, rough, or combined with substances [10] [4].
4. Confounders, measurement limits and alternative explanations
All reported associations come from observational, often self‑reported surveys: FI definitions vary (many use leakage at least monthly), “anal intercourse” is often recorded as lifetime ever vs. never rather than frequency/duration, and MSM convenience sampling bias and response framing can inflate prevalences [1] [4] [11]. Other risk factors—age, obstetric injury, neurological disease, socioeconomic status, bowel habits, concurrent high‑risk practices (fisting, chemsex), and reporting differences—could explain part or all of the observed differences, and some studies explicitly note these limitations [10] [4].
5. Practical interpretation and research gaps
Clinically, the literature supports asking about anal sexual practices when evaluating FI because a history of receptive anal intercourse is associated with higher reported FI and may influence diagnostic focus [1] [2]. However, data do not prove causation or quantify “long‑term” exposure effects precisely: longitudinal, objectively measured studies of anal sphincter structure/function, controlling for age, obstetric history and other confounders, are lacking and highlighted by reviews as a research priority [10] [4]. Until better prospective data exist, clinicians and researchers should interpret elevated FI rates among people reporting receptive anal intercourse as a signal for targeted assessment rather than definitive proof of causation.