The Rectum, Anal Sphincter and Puborectalis Muscle Show Different Contraction Wave Forms During Deferment of Simulated Feces

Abstract

Abstract Introduction. The contractile interaction of rectum, puborectalis muscle and anal sphincter must be studied to understand evacuation and consequences of deferred defecation. Methods. Six subjects were recruited to study contractile waveforms during deferred defecation with Fecobionics. The subjects filled out symptom questionnaires and had the balloon expulsion test and anorectal manometry done for reference. The Fecobionics bag was filled to urge-to-defecate volume in rectum. The subjects were asked to defer defecation for 4hrs. Pressures and bend angle variations were analyzed with Fast Fourier Transform (FFT). Two subjects were considered either constipated or hypersensitive. Results. The remaining four normal subjects were 23.8 ± 1.9yrs. Low frequency signals (< 0.06Hz) were found for pressures and bend angle. The waves were largely uncoordinated between recordings, except for rear and bag pressures. The frequency domain analysis showed waves with amplitude around 0.02-0.04Hz. Differences were found between the pressures and the bend angle both for peak 1 (ANOVA F = 9.403, p < 0.001) and peak 2 amplitudes (F = 5.48, p < 0.005). Post hoc tests showed that the front pressure amplitude was bigger than the others (rear and bend, p < 0.05; bag, p < 0.005) for peak 1, and bigger than bag pressure (p < 0.005) and bend angle (p < 0.05) for peak 2. The constipated subject had lower front pressure amplitudes compared to normal subjects. The other parameters had increased amplitudes. The hypersensitive subject also differed from normal subjects. Conclusions. The rectum, anal sphincter and puborectalis muscle showed different contraction waves during deferred defecation. The data call for larger studies to better understand the implications on anorectal disorders.