Effects of large-balloon dilation on the major duodenal papilla and the lower bile duct: histological evaluation by using an ex vivo adult porcine model.

BACKGROUND: Several articles have reported the usefulness of large-balloon dilation after endoscopic sphincterotomy in removing bile duct stones. Its histological effect on the duodenal papilla and the lower bile duct, however, is not well established. OBJECTIVE: To elucidate the histological consequence of large-balloon dilation. DESIGN: Animal experiment. SETTING: A referral center. MATERIALS AND INTERVENTIONS: After the evaluation of normal anatomy of the major duodenal papilla and the lower bile duct in resected specimens from pigs, large-balloon dilation (12-20 mm) after small sphincterotomy was performed, and serial tissue sections were assessed for morphological changes. MAIN OUTCOME MEASUREMENTS: Macroscopic and microscopic findings of the duodenal papilla and the lower bile duct after large balloon dilation, with special interest in ductal wall disruption and perforation. RESULTS: The porcine specimens were comparable in size to humans. Balloons with diameters 12 mm or larger caused disruption of the ductal walls, and those 15 mm or larger resulted in perforation of the surrounding adipose tissue. The frequency of disruption and perforation increased in proportion to the balloon diameters. LIMITATIONS: Other sequelae including hemorrhage, pancreatitis, acute inflammatory changes, and late fibrosis could not be investigated in our ex vivo porcine model. CONCLUSIONS: Dilation with large balloons can tear the bile duct wall and cause potential impairment of sphincter function and overdilation of small extrahepatic bile ducts.