Role of pressure and pancreatic reflux in the aetiology of choledochal malformation.

BACKGROUND

The aetiology of choledochal malformation is not known. Babbitt's hypothesis remains a popular concept, and assumes that activated pancreatic juice refluxes through the common pancreatobiliary channel causing mural damage and subsequent biliary dilatation. This hypothesis was tested clinically by evaluating the relationship between epithelial histology, choledochal pressure and degree of pancreatic reflux.

METHODS

Children with choledochal malformation (cystic, type 1c; fusiform, type 1f; both intrahepatic and extrahepatic dilatation, type 4) operated on between January 1999 and October 2009 were identified. Where practical, choledochal pressure was measured on entry to the abdominal cavity, by puncture of the common bile duct, and bile was sampled for amylase content. Archival bile duct sections were scored using a semiquantitative epithelial lining/mural score (ELMS).

RESULTS

A total of 90 children with choledochal malformations were operated on during the study interval. Histology was available for 73 children (median age 2·9 (interquartile range 1·3-7·9) years), 29 with type 1c, 31 with type 1f and 13 with type 4 malformations. There was a significant stepwise increase in pressure with choledochal morphology (median pressure 13, 17 and 20 mmHg for types 1f, 1c and 4 respectively; P = 0·037). There was an inverse relationship between choledochal pressure and bile amylase activity (r(s) = - 0·45, P < 0·001). High ELMS values were associated with higher choledochal pressure (P = 0·057) and low bile amylase activity (P = 0·002).

CONCLUSION

High choledochal pressure (not bile amylase) was associated with more severe histopathological changes and choledochal morphology. These findings suggest that distal bile duct obstruction (and therefore high intraluminal pressure) contributes more to the key features of choledochal malformation than does pancreatic reflux.