ABSTRACT
Objective To investigate precise and regulable animal model of benign bile duct strictures.Methods Mini pigs were divided into four groups as sham surgery group, conventional surgery group, small caliber group and large caliber group according to random number table, with 6 pigs in each group.For the small caliber group, outside diameter 3.0mm catheter were inserted into bile duct and partial sutured.For the large caliber group, outside diameter 6.0mm catheter were inserted into bile duct and partial sutured.Conventional surgery group were treated with 5-0 absorbable suture on distal bile duct and controlled stricture severity visually.For sham surgery group, bile duct were exposed without suture.Observe the general condition of four groups.Test liver function on 1st, 3rd, 7th, 14th, 21st and 28th day postoperative.Perform cholangiography on 30th day postoperative.All four groups were put to death to observe the histological changes of liver and bile duct.Results Liver function of sham surgery group showed no obvious change during observation.On 28th day postoperative, compared to conventional surgery group, the liver enzymes ALT, AST, γ-GT, ALP, bilirubin level of small caliber group elevated(P<0.05)and the liver enzymes ALT, AST, γ-GT, bilirubin level of large caliber group elevated(P<0.05),while ALP level lowered(P<0.05).Cholangiography showed bile duct stenosis of different degree on 6 pigs of small caliber group with average diameter 2.7mm (from 2mm to 4mm).As for large caliber group, 5 pigs showed stenosis with average diameter 5.5mm (from 5mm to 7mm).3 pigs of conventional surgery group showed no obvious bile duct stenosis.The 6 pigs of sham surgery group showed no bile duct stenosis.According to designed stenosis standard, the success rate of small caliber group and large caliber group are both higher than conventional surgery group.(P<0.05).30 days after surgery, all 6 pigs of small caliber group had postoperative intraperitoneal adhesion, hepatomegaly, obvious expansion of intrahepatic bile duct and gallbladder expanded by 4~5 times.5 pigs of large caliber group had hepatomegaly, slight dilation of intrahepatic bile duct, obvious expansion of gallbladder, clear choledochal edema, sutured tissue thickening and visible bile duct stenosis.HE staining with the small caliber group showed hepatocyte spotty degenerative necrosis, expanded cholestatic intrahepatic small bile duct, swelling hepatocyte and fibrous septa.HE staining with the large caliber group showed intrahepatic small bile duct slightly expanded and hepatocyte arranged basically normal.VG staining with the small caliber group showed excessive accumulaton of collagen fibers outside bile duct mucous cells, randomly and densely arranged and irregularly shaped.VG staining with the large caliber group showed increased collagen fibers in bile duct submucosa, densely and banded arranged.Conclusion This animal model of mini pig is an relatively ideal large animal model of biliary stricture with high surgical success rate and few postoperative complications.