Congenital cystic dilatation of the bile ducts, also known as congenital bile duct cysts, cystic dilatation of the bile ducts, choledochal cysts or idiopathic dilation of the common bile ducts, is a rare congenital anomaly that can involve the intrahepatic or extrahepatic bile ducts or both. The incidence is low in Western countries, about 1/13,000-15,000, but higher in Eastern countries, up to 1/1000 in Japan. about l/3 of patients are found in adulthood. Overall, choledochal cysts are more common than intrahepatic choledochal cysts (Caroli disease), and congenital choledochal cysts are a precancerous lesion with a cancer rate of about 2.5%-15%. However, bile duct carcinoma can still occur after choledochal cyst resection, which may be related to the abnormalities of the biliopancreatic duct confluence, that is, the carcinoma often occurs in the residual intrahepatic or pancreatic segment of dilated bile ducts, and more than half of them are due to inadequate cyst excision, and some adult patients have early carcinoma before choledochal cyst resection, so some scholars believe that complete choledochal cyst resection should be performed before puberty as much as possible. I. Causal factors or risk factors: The etiology of this disease is still unknown. Embryological theory: In 1936, Yotsuyairagi proposed that in the early embryonic stage, the bile duct epithelium proliferates unevenly, with uneven vacuolization, distal stenosis and proximal fragility forming cysts. 2. Abnormal pancreaticobiliary duct merging theory: In 1969, Babbitt proposed the common channel theory, which suggests that the pancreaticobiliary duct merging place is abnormal, forming an excessively long common channel (15 mm) or converging at a right angle opening. The high pressure pancreatic fluid flows backward into the bile duct, causing reflux cholangitis, and then the epithelium of the bile duct is shed, the wall of the duct gradually thins and expands outward, and finally the bile duct becomes cystic. 3, gastrointestinal neuroendocrine theory: In 1995, Shimotake et al. proposed that congenital bile duct cysts have significantly fewer neural stem cells in the bile duct wall than normal, and the number of reduced neural stem cells is positively correlated with the clinical symptoms and the degree of bile duct damage, and the cysts are caused by congenital gastrointestinal neuroendocrine regulation disorder. 4. A1dons-leij et al. suggested that the disease originated from congenital and acquired factors, i.e. congenital weakness of the bile duct wall, combined with multiple acquired factors causing intra-bile duct hypertension. 5, Other hypotheses. Such as viral infectious cholangitis before and after birth, intrauterine bile duct rupture, vascular accidents, etc. The typical clinical symptoms of congenital bile duct cyst are abdominal pain, jaundice and abdominal mass. 1, abdominal pain 60% to 80% of patients have abdominal pain, located in the right upper abdomen or the middle of the epigastrium, from mild dull pain, pulling pain, severe colic, often accompanied by nausea, vomiting, abdominal distension. 2, jaundice 33% to 70% of patients have jaundice, varying in depth, the depth is related to the degree of biliary obstruction, the deeper the jaundice, the more severe the obstruction is indicated. 3, abdominal mass 20% to 90% of patients have abdominal mass, the mass is usually located in the right upper abdomen, the surface is smooth. There is a cystic feeling. 4.Fever Fever and vomiting are often present during the attack, which is caused by biliary tract infection. 5.Signs Most patients have palpable abdominal masses, round, oval or pike shaped masses in the right upper abdomen, or upper abdomen, with smooth and clear borders, which can move from side to side, but often cannot move up and down, and can have clinical manifestations of acute abdomen when combined with infection, and in adults, sometimes easily confused with enlarged gallbladder. The congenital bile duct cysts are mostly seen in infants and children, 40-80% of patients are <12 years old, and 80% are female. With the development of imaging technology and the deepening of the understanding of this disease, its detection rate has increased significantly. 1, epigastric mass, abdominal pain, jaundice typical clinical symptoms. 2, B ultrasound, CT, PTC, MRCP, ERCP and intraoperative cholangiography help to diagnose congenital choledochal cysts. At present, B ultrasound is recognized as the preferred method, especially for primary hospitals, with the advantages of non-invasive, economical and reproducible, which can clearly show the size and morphology of the cyst, the degree of bile duct dilatation inside and outside the liver and the combined stones, etc. CT can accurately show the degree of bile duct dilatation inside and outside the liver and is an important auxiliary diagnostic method. The accuracy rate of MRCP can reach 100%. It is of great significance for the preoperative development of surgical plans and surgical operations. The cysts are located in the liver parenchyma and the bile ducts are inaccessible, so cholangiography and MRCP can help to differentiate them. Bile duct stones with bile duct dilatation Bile duct dilatation is less severe than bile duct cysts, and is uniformly dilated, without limited segmental dilatation. Once the diagnosis of congenital cystic dilatation of bile ducts is established, in principle, "internal drainage" should be performed at an early stage if there is no contraindication to surgery, while external drainage of cysts should be used when the patient is in poor general condition, cannot tolerate surgery and has serious complications. Different surgical methods are used according to different pathological staging. 1.Pathological staging The current common Todani staging method is to classify choledochal cysts into 5 types: Type I The common bile duct is dilated in a shuttle shape; the left and right hepatic ducts and intrahepatic bile ducts are normal, and the bile cyst ducts generally converge into cysts. It is the most common clinically, accounting for more than 90% of all choledochal cysts. Type II diverticulum-shaped cyst of the common bile duct, mostly from the lateral wall of the common bile duct, is rarely seen clinically. Type III choledochal terminal bulge, also called choledochal tumor, is a cystic prolapse of the opening of the common bile duct in the duodenum, and both the common bile duct and pancreatic duct enter the duodenum through the cyst, which is lined with duodenal mucosa. It is rare in clinical practice. It accounts for approximately 1.5% of common bile duct cysts. Type IVa multiple cysts of the intra- and extrahepatic bile ducts; Type IVb, multiple cysts of the extrahepatic bile ducts. Type V cystic dilatation of intrahepatic bile ducts (caroli disease). 2. For patients with type I cystic dilatation, cystectomy (including the dilated portion of the pancreatic segment) plus bile duct jejunostomy Rouen-Y anastomosis is now mostly recommended. Surgical principle: proximal end is cut on the basis of clean cyst with large caliber bile-intestinal anastomosis or large caliber hepatic duct jejunal end side anastomosis after bile duct plasticization. The scope of resection of the upper end of the common bile duct cyst is currently considered to require the retention of about 1 cm of the common hepatic duct with jejunal anastomosis after resection of the bile duct cyst, which can avoid postoperative anastomotic stenosis and cause painful reoperation. Some people believe that the common hepatic duct needs to be removed and then anastomosed after left and right hepatic duct shaping, but the caliber after shaping is still small, and anastomotic stricture is bound to occur after anastomosis with jejunum, which is prone to recurrent biliary tract infections after surgery. In patients with recurrent attacks and reoperation, those with serious adhesions between the cyst wall and surrounding tissues should first transect the cyst and separate the inner layer of the cyst wall from the fibrous tissue layer, similar to the operation of stripping the hernia sac, leaving the outer layer to prevent damage to the posterior portal vein and pancreatic tissue. For the treatment of the lower part of the cyst, after transection of the cyst wall, the opening of the lower bile duct in the cyst should be recognized first. If the opening is large, it is easy to peel off, but if the opening is very small (sometimes only crepitant), it needs to be carefully identified. You can also wait a little or gently massage the pancreas to encourage the flow of pancreatic fluid in order to identify the opening, which will help to estimate the downward course of the extracapsular common bile duct. Regardless of which anastomosis is used, the anastomosis requires a diameter of ≥2.0 cm. The length of the biliary collaterals of the common hepatic jejunostomy Roux-Y anastomosis should be kept at 35-40 cm to prevent reflux. 3. The commonly used methods for type II cysts include cystectomy, duodenal mastopexy and plication, and pancreaticoduodenectomy has also been reported. Type III cysts with abnormal biliopancreatic duct confluence undergo biliopancreatic duct separation at the same time of cystectomy. In recent years, endoscopic surgery has been gradually applied to the treatment of type III cysts, and has achieved better results. Type V caroli disease is still a difficult problem in treatment, and the various treatment methods currently used are difficult to achieve satisfactory results. It is generally believed that lobectomy or segmental resection is feasible for intrahepatic bile duct cysts limited to one section or lobe, and for multiple cysts in two lobes, the heavier side should be resected and the other side should be effectively drained internally; for diffuse cysts in two lobes, liver transplantation should be considered. If it is difficult to perform lobectomy, the cyst can be incised on the surface and cystic jejunostomy can be performed after removing the cystic contents such as stones. 5. Congenital bile duct cysts have a certain rate of cancer and should be taken seriously. If intraoperative cyst wall thickening or nodule formation is found, intraoperative freezing should be performed in time to exclude the possibility of carcinoma. After the diagnosis of carcinoma, cystectomy and hepatic duct jejunostomy are feasible in cases without lymph node metastasis, and cystectomy and pancreaticoduodenectomy are performed in cases with pancreatic head infiltration to improve postoperative survival quality and time. For cases with obvious local infiltration and difficulties in total cyst excision, partial cyst excision and hepatic duct jejunostomy are feasible, but the bile ducts in the hepatic sector must be enlarged and then anastomosed with jejunum to achieve the purpose of unobstructed drainage, otherwise it is equal to not completely solving the problem and the symptoms of biliary tract infection are still quite serious. 6, the previous surgical method of using bile duct cyst and duodenal anastomosis or bile duct cyst jejunostomy is wrong. The purpose of bile duct cyst and duodenal anastomosis is to make bile flow into the duodenum, but the observation results show that not only the bile cannot flow smoothly into the duodenum, but also the contents of the duodenum can flow back into the cystic cavity, making the cyst into a bag, and the contents accumulate more and more cannot be discharged, resulting in recurrent serious biliary tract infections, such surgery should be abandoned in the treatment of this disease. In patients with this surgery, the anastomosis is cut, the duodenum is repaired, the cyst is removed, and the bile duct is cured by Roux-Y anastomosis with the jejunum. In conclusion, congenital common bile duct cyst should be clearly diagnosed before surgery and treated with appropriate surgical methods according to the type of cyst and the specific situation of the cyst. Cystoduodenal anastomosis for choledochal cysts should be discarded, and cystojejunostomy is not an ideal procedure. Extrahepatic cysts should be treated along with intrahepatic cysts, and intrahepatic cysts should be treated with feasible hepatic resection and liver transplantation in severe cases, and extrahepatic cysts should be resected in cases of extrahepatic cysts. Common hepatic duct jejunostomy is a more ideal procedure at present.