ULTRASOUND / CLASSIFICATION OF CHOLEDOCHAL CYST

The most widely accepted classification is based on the cholangiographic morphology, location and number of intra- and extra-hepatic bile duct cysts (1).

Type I IA IB IC	(80-90% of cases). - Dilatation of common bile duct. - Dilatation of all or part of the extrahepatic biliary tree. - Intrahepatic biliary tree is normal. - Gallbladder arises from the choledochal cyst. - Focal segmental dilatation of the common bile duct (usually the most distal part). - A normal segment of common bile duct is present between the cyst and cystic duct. - Fusiform dilatation of the common bile duct. - Diffuse cylindric dilatation of the common hepatic duct. - Gallbladder arises from the dilated common bile duct. - Intrahepatic biliary system is not dilated.
Type II	- Choledochal diverticulum.
Type III	- Choledochocele that involves the intraduodenal portion of the common bile duct (looks like a ureterocele in the bladder)
Type IV IVA IVB	- Cyst involves dilatation of the intrahepatic and extrahepatic bile ducts. - Cyst involves dilatation of multiple segments but is confined to the extrahepatic bile duct. Intrahepatic biliary tree is normal.
Type V	- Caroli disease (multiple cystic dilatation of intrahepatic ducts without dilatation of the common bile duct).

REFERENCES

1. Todani T, Watanabe Y, Narusue M et.al. Congenital bile duct cysts. Am J Surg 1977;134:263-269.