Flatus Incontinence and Fecal Incontinence: A Case-Control Study

BACKGROUND: Incontinence to gas can be a troublesome symptom impacting quality of life for patients even in the absence of fecal incontinence. Whether isolated flatus incontinence represents part of the spectrum of true fecal incontinence or a separate condition with a different pathophysiology remains unclear.OBJECTIVE: This study aimed to evaluate the clinical features and anorectal physiology in women presenting with severe isolated flatus incontinence compared to women with fecal incontinence and healthy asymptomatic women.DESIGN: This was a retrospective case-control study of prospectively collected data.SETTINGS: Data from participants were obtained from a single tertiary Neurogastroenterology Unit in Sydney, Australia.PATIENTS: Data from 34 patients with severe isolated flatus incontinence, 127 women with fecal incontinence, and 44 healthy women were analyzed.MAIN OUTCOME MEASURES: The primary outcomes were clinical (including demographic, obstetric, and symptom variables) and physiological differences across the 3 groups.RESULTS: Patients with flatus incontinence were significantly younger (mean 39 versus 63 years; p = 0.0001), had a shorter history of experiencing their symptoms (p = 0.0001), and had harder stool form than patients with fecal incontinence (p = 0.02). Those with flatus incontinence had an adverse obstetric history and impaired anorectal physiology (motor and sensory, specifically rectal hypersensitivity) but to a lesser extent than patients with fecal incontinence.LIMITATIONS: This study was limited by its retrospective design and modest sample size.CONCLUSIONS: Anorectal physiology was impaired in patients with flatus incontinence compared to healthy controls, but to a lesser extent than in those with fecal incontinence, raising the possibility that flatus incontinence could be a precursor to fecal incontinence. As clinical and physiological findings are different from healthy controls (including the presence of visceral hypersensitivity), isolated flatus incontinence should be considered a distinct clinical entity (like other functional GI disorders), or possibly part of an incontinence spectrum rather than purely a normal phenomenon.