ANORECTAL ANGLE ENHANCES FECAL CONTINENCE

This study was performed with an in vitro model to assess the relative importance of sphincter pressure and anorectal angulation in maintain ing faecal continence. Water and semisolid material were infused separ ately into porcine intestine compressed by an inflatable cuff until le akage was observed. Angulation of the bowel with respect to the cuff w as 180 degrees and then 90 degrees. With water, holdback pressure was independent of angulation. In contrast, when semisolid material was us ed, angling the bowel to 90 degrees increased holdback pressure by at least 100 per cent. Measurements taken in solid tubes demonstrated tha t both a restriction in the tube and an unconstricted 90 degrees bend produced a resistance to flow of the semisolid material which was depe ndent 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.