Ans. is 'd' i.e., Rupture may lead to biliary peritonitis Choledochal cyst* A choledochal cyst is an isolated or combined congenital dilatation of the extrahepatic or intrahepatic biliary tree.Classification of Choledochal cystType I- a type I cyst is characterized by fusiform dilatation of the bile duct.- this is the most common typeType II- a type II cyst appears as a diverticulum protruding from the wall of the CBD.Type III- a type III cyst is dilatation of the biliary tract within the duodenum; also k/a choledochoceleType IV Type IV A- multiple dilatation of the intrahepatic and extrahepatic bile ducts.Type IV B- multiple dilatation involving only the extrahepatic bile ducts.Type V- consists of multiple dilatation of the intrahepatic bile ducts; also known as Carolis disease.* Choledochal cysts are seen to be frequently associated with an anomalous junction of the pancreatic and biliary duct.Clinical Presentation* More common in females than in males (4:1)* Typically choledochal cysts present in children beyond the toddler age group.* The classical triad presents only in a minority of patients; it consists of:# Abdominal pain# Jaundice# Abdominal mass* If the disorder is left undiagnosed, patients may develop cholangitis or pancreatitis. Cholangitis may lead to the development of cirrhosis and portal hypertension.Complications caused by choledochal cyst* Recurrent cholangitis* Portal vein thrombosis with resultant portal hypertension* Pancreatitis* Cyst rupture with biliary peritonitis (very rarely)* Gall stones* Malignancy* Cirrhosis with portal hypertension Diagnosis* ERCP is the most reliable investigation but is invasive* MRCP is the best noninvasive investigationTreatment* Cholecystectomy + Cyst excision with reconstruction via a biliary-enteric Roux-en-Y anastomosis is the treatment of choice for all choledochal cysts except type III (choledochocele) and intrahepatic cysts of type IV & type V (Carolis disease)* Treatment of type III (Choledochocele)# Transduodenal sphincteroplasty or sphincterotomy# cyst excision* Treatment of intrahepatic cysts of type IV & V# If the intrahepatic cysts are localized, hepatic lobe is resected# If the intrahepatic cysts are diffuse only effective treatment is liver transplantation.