Coordinated activity of the new "rectum" and anal sphincter after sphincter-saving resection of the rectum for colitis or carcinoma.

PURPOSE: The aim of this study was to determine whether coordinated activity exists across a stapled enteroanal anastomosis.

METHODS: Twenty-nine patients were studied for a median of one year after complete excision of the rectum and stapled enteroanal anastomosis; 12 patients underwent low anterior resection with coloanal anastomosis for carcinoma, and 17 patients underwent restorative proctocolectomy with ileoanal anastomosis.

RESULTS: Maximum anal resting pressures were slightly lower after coloanal anastomosis than after ileoanal anastomosis [median range, 56 (11-60) cm H2O, cf 69 (40-107) cm H2O, P = NS]. During distention of the neorectum, anal sphincter pressures at 2.5, 1.5, and 0.5 cm from the anal verge were significantly lower after coloanal anastomosis compared with after ileoanal anastomosis (P < 0.01 at each station). The volume of neorectal distention required to produce maximal inhibition of the anal sphincter was significantly less after coloanal anastomosis at 50 (range, 20-60) ml of air than after ileoanal anastomosis at 240 (range, 100-420) ml of air (P < 0.01). Minor fecal leakage and urgency of bowel action were significantly more common after coloanal anastomosis (P < 0.01).

CONCLUSION: Alterations in the dynamic response of the anal sphincter to distention of the neorectum may explain why the clinical results were better after ileal pouch-anal anastomosis than after coloanal anastomosis.