Aim: To introduce and evaluate a new method to repair bile duct defect with a degradable stent and autologous tissues.
Methods: Eight Ba-Ma mini-pigs were used in this study. Experimental models with common bile duct (CBD) defect (0.5-1.0 cm segment of CBD resected) were established and then CBD was reconstructed by duct to duct anastomosis with a novel degradable stent made of poly [sebacic acid-co-(1,3-propanediol)-co-(1,2-propanediol)]. In addition, a vascularized greater omentum was placed around the stent and both ends of CBD. Cholangiography via gall bladder was performed for each pig at postoperative months 1 and 3 to rule out stent translocation and bile duct stricture. Complete blood count was examined pre- and post-operatively to estimate the inflammatory reaction. Liver enzymes and serum bilirubin were examined pre- and post-operatively to evaluate the liver function. Five pigs were sacrificed at month 3 to evaluate the healing of anastomosis. The other three pigs were raised for one year for long-term observation.
Results: All the animals underwent surgery successfully. There was no intraoperative mortality and no bile leakage during the observation period. The white blood cell counts were only slightly increased on day 14 and month 3 postoperatively compared with that before operation, the difference was not statistically significant (P = 0.652). The plasma level of alanine aminotransferase on day 14 and month 3 postoperatively was also not significantly elevated compared with that before operation (P = 0.810). Nevertheless, the plasma level of γ-glutamyl transferase was increased after operation in both groups (P = 0.004), especially 2 wk after operation. The level of serum total bilirubin after operation was not significantly elevated compared with that before operation (P = 0.227), so did the serum direct bilirubin (P = 0.759). By cholangiography via gall bladder, we found that the stent maintained its integrity of shape and was still in situ at month 1, and it disappeared completely at month 3. No severe CBD dilation and stricture were observed at both months 1 and 3. No pig died during the 3-mo postoperative observation period. No sign of necrosis, bile duct stricture, bile leakage or abdominal abscess was found at reoperation at month 3 postoperatively. Pigs had neither fragments of stent nor stones formed in the CBD. Collagen deposit was observed in the anastomosis by hematoxylin and eosin (HE) and Masson's trichrome stains. No severe cholestasis was observed in liver parenchyma by HE staining. Intestinal obstruction was found in a pig 4 mo after operation, and no bile leakage, bile duct stricture or biliary obstruction were observed in laparotomy. No sign of bile duct stricture or bile leakage was observed in the other two pigs.
Conclusion: The novel method for repairing bile duct defect yielded a good short-term effect without postoperative bile duct stricture. However, the long-term effect should be further studied.
Keywords: Autologous tissue; Bile duct defect; Biliary reconstruction; Degradable stent; Omentum.