An Experimental Study On Flip-flop Repair Of The Extrahepatic Bile Duct Defect With Parietal Pedicled Peritoneal Graft

Objective: Extrahepatic bile duct injuries after open and laparoscopic cholecystectomies cause significant morbidity and mortality. Common bile duct injuries can be repaired by various autograft. In the experimental, we used the pedicled peritoneal graft to flip-flop repair the extrahepatic bile duct defect, and observed the change of blood biochemical parameters. The tissues of liver, the pedicled peritoneal graft and common bile duct, especially the repaired segment were harvested for light microscopic examination and the expression of TGF-β1 was studied by using Immunohistochemical SP staining method to evaluate the healing process of bile duct and morphological changes in liver. The experimental was to explore the feasibility of using pedicled peritoneal graft to flip-flop repair the extrahepatic bile duct defect and to find an ideal material and a good procedure for the clinical management of the bile duct injury.Methods: The experimental was carried out on twenty male rabbits of which weighting 2.2～2.5kg. The first part of the study involved intentionally creating an incomplete obstruation of the common bile duct by ligature and a conventional cholecystectomy was performed. Three days after the ligation, as the second part of the experimental study, a celiomtomy was performed and 0.8-1.0cm of the anterior one-third to two-third of the bile duct was resected to establish the model of bile duct infect. The appropriate pedicled peritoneal graft was harvested near the abdominal incision with the similar dimension of the bile duct defect and sutured to the edges of the excised bile duct.The rabbits were observed the change of appetite, action, spirit, dejecta and so on. Blood samples were obtained during the preoperative and postoperative phase of the study for measure TBil, DBiL, TBA, AST and ALT levels.Laparotomy was performed again at following interval: 1 weeks (n=4), 2 weeks (n=4), 3 weeks (n=4), 5 weeks (n=4), 12 weeks (n=4). The tissues of liver, the pedicled peritoneal graft and common bile duct, especially the repaired segment were harvested for light microscopic examination and the expression of TGF-β1 was studied by using immunohistochemical SP staining method.Results: Two rabbits died on the postoperative 9th day and 15th day. The other eighteen rabbits were healthy at the time of killing with normal appetite and body weight without jaundice. By 3 days after ligation, there was an increase in serum biochemical levels. AST and ALT were 33.58±2.76U/L, 58.23±6.30U/L, lightly increased over preoperation. By 7 days, AST and ALT were 24.20±1.59 U/L, 43.93±3.98 U/L, being of no evident difference to preoperation. By 3 days after ligation, TBiL,DTiL and TBA were 14.8±2.62umol/L, 5.58±0.57 umol/L, 4.93±0.76 umol/L, significantly increased over preoperation(P<0.05). By postoperative 1 weeks, the serum Bilirubin and bile acid decreased obviously, being of no evident difference to preoperation(P>0.05).By postoperative 2 weeks, the bile duct especially the repaired segment was found to be surrounded by fibrous tissue and adhesions from the liver to the duodenum. The repaired segment could be recognized clearly, and the inner surface was dyed by bile. Proximal end of the common bile duct had lightly edema, and broadened obsoletely. By prosthesis 5 weeks, the pedicled peritoneal graft was found to surrounded by connective tissue and adhered closely with the surrouding tissues. The repaired segment could be ambiguous recognized. The inner surface could be recognized by fovea centralis. The peripherals were the transitional mucosas of the bile duct. By postoperative 12 weeks, the repaired segment could be recognized hardly, the smooth inner surface was covered by mucosas of the bile duct. The bile duct wall was similar to the normal rabbit's common bile duct.At repaired operative 1 weeks, manipulus inflammatory cells around hepatocytes and light swelling of hepatocytes were been found.By the second week, hepatocytes swelling and inflammatory cells relieved obviously. The edge of the patch showed signs of tissue incorporation with deposition of native collagen. Biliary epithelium was evident at the edges of graft. The predominate cells included macrophages, histiocytes, fibroblasts, and polymorphonuclear cells.By the third week, the hepatic tissue did not show any changes. Cholerythrin accumulate in the cholangiole and Kupffer's cells were not been discoveried. It showed increasing signs of incorporation. The inflammatory response lessened with the cellular infiltrate comprised predominantly of fibroblasts and scant macrophages. The bile duct wall was composed of fibrous tissue similar to the normal rabbit's common bile duct.By the fifth week, mostly of the inner surface of the graft was covered with biliary tract epithelium. The inflammatory response lessened obviously with the cellular infiltrate comprised predominantly of fibroblasts and scant macrophages, and integrity micrangiums was visited.By the twelveth week, the inner surface of the graft was almost covered with biliary tract epithelium.In the repaired segment, TGF-β1 was expressed strongly within 2 weeks, the number of masculine cells were 63.8±5.2. By 5 weeks, the number of masculine cell was 40.5±6.1. By 12 weeks TGF-β1 were expressed weakly(18.3±2.7), which had no significant difference from preoperation (P>0.05).Conclusion: Experimental result confirms that the survival rate of Peritoneum was high and interchange adaptive capacity was strong after flip-flop repair of the extrahepatic bile duct defect with parietal pedicled peritoneal graft. The surface of peritoneum was vegetative covered by the Biliary epithelium gradually. Peritoneum was an ideal repaired material because of such advantages as abundance, potential ability of regeneration, antibacterial effect, convenience and so on. And the operation was simply and convenient. The low expression of TGF-β1 in the later postoperative period, which indicated impossibility of biliary stricture. Flip-flop repair of the extrahepatic bile duct defect with parietal pedicled peritoneal graft was a good procedure for repair of bile duct defect.