PROSPECTIVELY EVALUATING ANAL-SPHINCTER FUNCTION AFTER ILEAL POUCH-ANAL CARNAL ANASTOMOSIS

The decreased anal sphincter pressure that occurs after ileal pouch-an al canal anastomosis (IPAA) has usually been attributed to damage of t he internal anal sphincter. We hypothesized that the operation damages both the internal and the external anal sphincter. Resting pressure i n the anal canal (a function of internal and external sphincters), ana l squeeze pressure (a function of external sphincter only), and the re ctal-anal inhibitory reflex (involving the internal sphincter) were me asured manometrically in 10 patients with ulcerative colitis (4 women and 6 men; clean age, 33 years; range: 20 to 49 years). The patients w ere studied while a awake before IPAA, under general anesthesia with s triated muscle blockade just before incision, awake 2 months later bef ore ileostomy takedown, and again under anesthesia with blockade just before takedown. The operation decreased maximum resting; anal pressur e while awake and during anesthesia with blockade. The decrease was de tected in the proximal anal canal but not in the distal anal canal. In addition, the operation impaired anal squeeze pressure and abolished the rectal-anal inhibitory reflex. We conclude that IPAA damages both the internal and the external anal sphincter.