The rectum, anal sphincter and puborectalis muscle show different contraction wave forms during prolonged measurement with a simulated feces.

Contractile patterns in rectum, puborectalis muscle and anal sphincter must be studied to understand defecation. Six subjects had contractile waveforms studied with Fecobionics. Symptom questionnaires, balloon expulsion test and anorectal manometry were done for reference. The Fecobionics bag was filled in rectum to urge-to-defecate volume and measurements were done for 4 h before the subjects attempted to evacuate the device. Pressures and bend angle (BA) variations were analyzed with Fast Fourier Transformation. Four normal subjects exhibited low frequency waves (< 0.06 Hz) for pressures and BA. The waves were uncoordinated between recordings, except for rear and bag pressures. Peak wave amplitudes occurred at 0.02-0.04 Hz. Pressures and the BA differed for peak 1 (p < 0.001) and peak 2 amplitudes (p < 0.005). The front pressure amplitude was bigger than the others (rear and BA, p < 0.05; bag, p < 0.005) for peak 1, and bigger than bag pressure (p < 0.005) and BA (p < 0.05) for peak 2. One subject was considered constipated with lower front pressure amplitudes compared to normal subjects and increased amplitudes for other parameters. The sixth subject was hyperreactive and differed from the other subjects. In conclusion, the rectum, anal sphincter and puborectalis muscle showed different contraction waves during prolonged measurements. The data call for larger studies to better understand normal defecation, feces-withholding patterns, and the implications on anorectal disorders.