Development of a swine model for benign stenosis of the bile duct by endoscopic application of intraluminal thermal injury

Background. A simple animal model is desirable for the study of endoscopic therapies used in the management of biliary strictures. The aim of this study was to identify a method for inducing benign biliary stenoses in a porcine model by using endoscopic techniques. Methods: Endoscopic retrograde cholangiography was performed in 9 swine. Intraluminal injury was applied to the common hepatic duct with graded applications of either a heat probe or a multipolar probe. Cholangiography was repeated at 7-day intervals. If a stricture was not identified by 28 days, injury was created at another site in the common hepatic duct by using a higher energy dose. After a stricture was identified, the animal was killed and bile duct samples were obtained for histopathologic evaluation. Results: Thirteen thermal injuries were created in the 9 animals. Six of 7 heat probe treatments and 1 of 6 multipolar probe treatments resulted in a stricture (p = 0.025, Fisher exact test). Applications of the heat probe at 10 or 15 J produced a stricture in 6 of 6 cases. All strictures were indistinguishable histopathologically from benign strictures in humans. Conclusions: The application of intraluminal thermal injury with a heat probe results in a reproducible animal model of benign biliary stenosis.