Congenital cystic dilatation of the common bile duct: relationship to anomalous pancreaticobiliary ductal union.

Thirty patients from 15 to 69 years of age with congenital cystic dilatation of the common bile duct were studied. The diagnosis was made by intravenous cholangiography in 70% of the patients and by percutaneous transhepatic cholangiography and/or endoscopic retrograde cholangiopancreatiography in the entire group. Cystic dilatation was also noted in the intraphepatic bile ducts in 12 patients. A union between the common bile and main pancreatic ducts occurred at a high position in 17 of 18 patients in whom both ducts were adequately opacified, forming an abnormally long common channel. One patient with choledochodele had a normal union. The anomalous unions were of two types: the pancreatic duct entering the common duct and the common duct entering the pancreatic duct. The mode of union was correlated with the degree of extrahepatic bile duct dilatation, age of onset, and frequency and severity of symptoms. It is postulated that the congenital anomaly in the union of the two duct systems is the cause of the disease and the congenital choledochocele has a different etiology.