Coexistence of intrahepatic bile duct dilatation is not so uncommon in congenital dilatation of the bile duct. Intrahepatic bile duct dilatation was disclosed by operative cholangiography in 39 of the 47 patients who had undergone radical operation of choledochal cypt at 2nd Department of Surgery, Tohoku University Hospital. Primary excision of the cyst was employed for these patients and intrahepatic bile duct involvement of the bile ducts had been left at the time of operation. In follow-up studies ranging 1 to 12 years after the operation, none of these 39 patients had complication such as ascending cholangitis, intrahepatic lithiasis and cancer arising from intrahepatic bile ducts. Ultrasonography of the liver taken at follow-up study revealed no dilatation in all of cases showing fusiform dilatations and in 7 of 9 cases showing cystic dilatations at the time of radical operation. The size of 2 cases of giant cystic dilatation of intrahepatic bile ducts scarcely unchanged. The results of these follow up studies will justify an employment of free drainage procedure at the porta hepatis for surgical treatment of congenital dilatation of the bile duct. Careful follow-up study should be required, however, when patient has a huge cystic dilatation of the intrahepatic bile duct.
