Increased fatigability of external anal sphincter in inflammatory bowel disease: significance in fecal urgency and incontinence

Abstract

Background and aims: Fatigability of external anal sphincter (EAS) has not been studied in inflammatory bowel disease (IBD) patients. We evaluated EAS fatigability in IBD patients with and without fecal incontinence (FI) and urgency, and correlated fatigability with demographic and clinical factors, and EAS endosonography.

Methods: Fifty-eight consecutive IBD cases and 14 healthy volunteers completed Bristol stool form and a FI severity scale. Groups I, II and III included 27 patients with urgency including 13 with concomitant FI, 31 patients without FI or urgency, and 14 controls, respectively. We performed stationary pull-through manometry with an 8-channel water-perfused catheter. Fatigue rate (FR) was calculated by linear regression during a 20-s anal squeeze, and fatigue rate index (FRI) as the ratio of squeeze pressure increment to FR. EAS thickness and deficits were evaluated with an endoanal 10-MHz probe. Patients underwent sigmoidoscopy.

Results: Group I demonstrated a higher Bristol score, more frequent defecations, and more EAS defects compared to group II. Resting, peak squeeze pressures and EAS thickness did not differ between groups. FR was increased in group I versus II, and in group II versus III; FRI was decreased in group I versus II and in group II versus III (p<0.001, adjusting for age and BMI). Gender, oral glucocorticoids, presence of proctitis, perianal disease and EAS defects did not interact with group membership on FR or FRI.

Conclusions: IBD is associated with increased fatigue rate and decreased fatigue rate index. These differences were even more striking in patients with incontinence or urgency.