Anorectal angle enhances faecal continence

Abstract

This study was performed with an in vitro model to assess the relative importance of sphincter pressure and anorectal angulation in maintaining faecal continence. Water and semisolid material were infused separately into porcine intestine compressed by an inflatable cuff until leakage was observed. Angulation of the bowel with respect to the cuff was 180 degrees and then 90 degrees. With water, holdback pressure was independent of angulation. In contrast, when semisolid material was used, angling the bowel to 90 degrees increased holdback pressure by at least 100 per cent. Measurements taken in solid tubes demonstrated that both a restriction in the tube and an unconstricted 90 degrees bend produced a resistance to flow of the semisolid material which was dependent on flow rate. These data suggest that liquid is retained in the rectum by occlusion pressure alone, whereas the retention of semisolid material is enhanced by angulation.

Anorectal Sensation and Continence

“…The puborectalis muscle contracts both in response to an increase in intra-abdominal pressure and in response to rectal filling (16). This apparent discrepancy may be due to the nature of the stool, since Hajivassiliou et al (22) have shown that the anorectal angle has a greater role in the maintenance of semisolid than liquid stool continence. There are conflicting data with regard to the importance of the anorectal angle in the clinical maintenance of continence.…”

Preoperative MRI sphincter morphology and anal manometry: can they be markers of functional outcome following anterior resection for rectal cancer?

“…It is interesting, given the effect of puborectalis on anorectal angle, that the latter was not significant on univariate analysis ( P = 0.08), considering that there is evidence for its role in affecting continence [20]. It is perhaps more important to focus on the reduction in anorectal angle when the pelvic floor contracts as opposed to the normal resting angles observed in this study.…”

A Physical Simulation to Investigate the Effect of Anorectal Angle on Continence

“…Notably, in vitro studies have shown that increasing ARA reduces the occlusion pressure required to hold back solids and semi-solids [22,23]. Similarly, another study reported increased retention of semisolid material when increasing ARA in an ex vivo porcine rectum, but no effect for water [23].…”

“…Notably, in vitro studies have shown that increasing ARA reduces the occlusion pressure required to hold back solids and semi-solids [22,23]. Similarly, another study reported increased retention of semisolid material when increasing ARA in an ex vivo porcine rectum, but no effect for water [23]. The question of whether the ARA or sphincter occlusion pressure is a greater contributor to continence remains unanswered, despite previous studies comparing the two [24,25].…”