Histologic sequelae of endoscopic sphincterotomy: a canine experiment.

: Concern for the late formation of strictures at the site of an endoscopic sphincterotomy has delayed the acceptance of this procedure as treatment for choledocholithiasis in otherwise healthy patients. The authors addressed this issue by comparing the biochemical and histologic sequelae of sphincterotomy in 23 dogs with those in 10 sham-operated controls. Twenty-four hours after sphincterotomy, hemorrhagic, edematous mucosa surrounded the incision. Microscopically, there was an acute inflammatory exudate bridging the mucosal surfaces. Mucosal regeneration was sufficient after 1 week to cover the defect caused by the cautery, although some inflammatory changes were still evident. A widely patent sphincterotomy orifice was seen in 15 dogs followed up for 10 weeks. In three dogs, the fibres of the papilla had reunited below the incision, resulting in a choledochoduodenal fistula. Histologically, complete healing of the mucosal surface had occurred with no evidence of scar formation or chronic inflammation. Serum bilirubin and liver enzyme measurements did not show evidence of biliary obstruction due to the sphincterotomy. From the results of our study, there is no evidence to suggest that an endoscopic sphincterotomy is predisposed to late stenosis.