Changes of Bile Duct Mucosa after Choledochoduodenostomy in Rats

Abstract

This study investigated the changes of bile duct mucosa in rats after choledochoduodenostomy. Wistar rats were divided into three groups: group I (n = 6) was treated with sham operation as control; group II (n = 10) was treated with common bile duct ligation without choledochoduodenostomy, and group III (n = 12) had both common bile duct ligation and choledochoduodenostomy creation 4 days after common bile duct ligation. From our observations, retrograde induced cholangitis due to enteric reflux into the common bile duct is the possible cause of chronic inflammation after choledochuduodenostomy. At the end of the study, Choledocholithiasis developed in 5 of 12 rats. Severe dysplasia was present in the bile duct mucosa in 6 of 12 rats in group III, but not in group I or II. A technique for silver staining of nucleolar organizing regions (AgNOR) was applied. This technique demonstrated differences in AgNOR counts between normal mucosa and dysplasia. Under AgNOR stain, the number of AgNOR was significantly greater than in the normal or benign counterparts and gradually increased from the normal bile duct mucosa group to the severe dysplasia group (group I 2.1 +/- 0.8, group II 3.2 +/- 1.0, group III 5.3 +/- 1.1). All of these observations suggest that 'sump syndrome' and bile stasis could occur after choledochoduodenostomy in rats and can result in chronic inflammation of the bile duct. It has been well established that calcium bilirubinate is the major type of choledocholithiasis in Orientals. beta-Glucuronidase from bacteria, such as Escherichia coli present in the biliary tree, hydrolyzes bilirubin diglucuronide to bilirubin. Bilirubin combines with calcium in the bile flow to form calcium bilirubinate. Bacterial infection plays a key role in calcium bilirubinate stone formation. Since choledochoduodenostomy did increase reflux cholangitis, and bacterial infection would increase mucin overproduction, bile deconjugation and eventually new calcium bilirubinate stones would be formed. The dysplastic changes in the bile duct mucosa could possibly be related to the prolonged exposure to the biochemically altered infected bile. Thus choledochoduodenostomy might not be the perfect choice in treating calcium bilirubinate choledocholithiasis in Orientals.