Bile duct cysts can be divided into four types: Type I: cystic or pyknotic dilatation of the common hepatic duct, common bile duct, or a portion thereof. Type II: diverticulum-like dilatation of the common bile duct wall with a thin tip attached to the common bile duct. Type III: cysts in the inner segment of the duodenal wall Type IV: multiple dilatation of the intra- and extrahepatic bile ducts IVB multiple dilatation of the extrahepatic bile ducts Type V, also known as Caroli disease, has a single or multiple cysts in the intrahepatic bile ducts. The main symptoms of bile duct cysts are obscure epigastric or right epigastric pain, jaundice, and palpable mass in the right epigastrium. As well as longer term bile duct obstruction or stone formation due to recurrent biliary duct infections, liver abscess, pancreatitis cirrhosis, portal hypertension, etc. Ultrasound examination of the abdomen can detect bile duct dilatation, stone formation, portal vein thrombosis, liver abscess, bile duct mass, etc. CT examination can clarify the staging of bile duct cyst and guide the surgical treatment plan. ERCP and MRI, MRCP can clarify the presence or absence of pancreatic duct dilatation and lesions distal to bile duct dilatation. Since choledochal cysts in adults can cause recurrent cholangitis and may lead to cancer, it is currently considered that once diagnosed, surgical treatment should be performed by resection of all extrahepatic bile ducts (type I, II, IV), cystectomy + duodenal papillotomy and plication (type III), lobectomy for type V confined to one lobe, or liver transplantation for those with biliary cirrhosis.