Choledochal cysts are congenital bile duct anomalies involving cystic dilatations of the biliary tree that can involve the extrahepatic biliary radicles, the intrahepatic biliary radicles, or both.

Todani and colleagues classified Choledochal cyst into five major types and several subtypes. Type I cysts are a dilatation of the extrahepatic bile duct. They are the most common type and seen in 75–85% of cases. Type I cysts may be further classified as cystic (IA), focal (IB) or fusiform (IC). The type II cyst is diverticulum of the common bile duct. Type III is represented by a cystic dilatation of the intramural portion of the common bile duct known as choledochoceles. Type IVA lesions involve both the intra and extrahepatic portions of the bile ducts, and type IVB are multiple cysts limited to the extrahepatic bile ducts. Type IVA cysts are the second most common type after type I. Type V is synonymous with Caroli disease and describes the abnormalities of the intrahepatic bile ducts, resulting in multiple segmental intrahepatic cystic biliary dilatations.

Ultrasound (US) is the best initial method for evaluating the entire intrahepatic and extrahepatic biliary system and gall bladder. US shows a choledochal cyst as a characteristic cystic or fusiform dilatation of common hepatic duct or the intrahepatic ducts or sometimes a cyst in the porta hepatis, separate from the gallbladder. MRCP is emerging as a highly sensitive, safe, and noninvasive diagnostic preoperative technique for the detection of choledochal cysts. MRCP is rapidly replacing diagnostic ERCP in various pancreaticobiliary diseases. 

Laparoscopic surgery has revolutionized the treatment of choledochal cysts (CDC). 

Although hepaticoduodenostomy seems to be technically easier and delivering bile directly into the duodenum is more physiological, hepaticoduodenostomy has been questioned by some because of the post-operative cholangitis and bile gastritis.