The rectoanal inhibitory reflex (RAIR) is important in gas and stool evacuation. We examined RAIR features in patients with chronic constipation who exhibited bloating with and without abdominal distension, to determine if alterations in RAIR may be a factor in the pathogenesis of abdominal distension. 75 female patients with chronic constipation with or without abdominal distension were included in the study. The presence or absence of abdominal distension was assessed according to the Rome II questionnaire. All patients underwent both RAIR and rectal sensitivity testing, and specific RAIR parameters were analysed. Patients were divided into two groups: abdominal bloating with distension (D, n=55) and abdominal bloating without distension (ND, n=20). D had a longer time to the onset of anal sphincter inhibition (latency of inhibition, Li) (p=0.03) compared to ND. In logistic regression analysis, a combination of age, Li and the time measured from onset of inhibition to the point of maximum inhibition (Tmax) predicted abdominal distension (p=0.002). There were no differences between groups for the time from point of maximum inhibition to recovery (Trec) and for the percentage of internal anal sphincter relaxation. This is the first study to examine the role of RAIR in patients with abdominal distension. Females with constipation and abdominal distension exhibited differences in the temporal characteristics of, but not in the degree of, anal sphincter relaxation compared to patients without distension. Since this study was uncontrolled, further studies are necessary to determine the contribution of altered anorectal reflexes to abdominal distension.
- abdominal distension
- rectoanal inhibitory reflex