Congenital common bile duct cyst, also known as congenital bile duct dilatation, is a relatively common congenital biliary malformation in pediatric hepatobiliary surgery. The disease is characterized by cystic or pyknotic dilatation of a portion of the common bile duct, sometimes accompanied by dilatation of the intrahepatic bile duct. We often encounter a variety of questions from the families of children in clinical work, so we will summarize and explain these to facilitate families to have a clearer understanding of common bile duct cysts. 1.What are the common clinical manifestations of congenital choledochal cyst? The three typical symptoms of the disease are abdominal pain, jaundice of the skin and sclera and abdominal mass, but it is usually seen most often as one or two of these symptoms, and the chance of all three symptoms appearing together is less, accounting for only 20%-30%. 2.What are the commonly used tests? B-ultrasound is the most commonly used method to diagnose choledochal cyst, and its diagnostic rate is high, reaching more than 95-98%. For the majority of patients with choledochal cyst, B-ultrasound alone can make a clear diagnosis. At Guangzhou Women’s and Children’s Medical Center, we routinely check MRI water imaging scan, or MRCP (which is a method of MRI), in addition to ultrasound examination before surgery. MRCP examination can clearly show the morphology of bile ducts inside and outside the liver, which can not only make a clear diagnosis, but also show the dilatation and stenosis of intrahepatic bile ducts, which is helpful for preoperative formulation of surgical plan and avoid the corresponding postoperative problems due to the omission of intrahepatic bile duct stenosis during surgery It is also helpful for the preoperative planning of the operation and to avoid the corresponding postoperative complications caused by the missed intrahepatic bile duct strictures. The choice of surgical method Open choledochal cyst excision + bile duct reconstruction is the traditional surgical method. At present, laparoscopic surgery for choledochal cyst has been recognized as the best minimally invasive surgical method and is gradually becoming the standard surgical treatment for choledochal cyst. Laparoscopy has a magnifying effect and enables more precise surgical operations to be accomplished. Laparoscopic surgery is characterized by small intraoperative damage and fast postoperative recovery, which generally allows you to eat 2-3 days after surgery and to be discharged from the hospital in 5-7 days. 4, the timing of surgery once the diagnosis of choledochal cyst should be surgical treatment. For children found during pregnancy and delivery, abdominal ultrasound should be reviewed after birth to clarify the diagnosis of common bile duct cyst, and generally asymptomatic children do not need immediate surgery, and it is safer to wait until 3 months after birth. However, if there are symptoms such as obstructive jaundice after birth, surgery should be performed promptly within 3 months, and it is not necessary to wait until after 3 months. 5.The possible consequences of not doing surgery After the diagnosis is clear, we recommend early surgery. If surgery is not performed, symptoms such as abdominal pain and jaundice as described above may occur, and the symptoms may recur, causing unnecessary pain and, with age, may even become cancerous. Although cancer mostly occurs in adulthood, it has also been reported to occur in children and young adults.