Bile duct ectasia is a common congenital bile duct malformation, which used to be considered as a lesion confined to the common bile duct, so it is called congenital choledochal cyst. The diagnosis of this disease can be considered according to three main symptoms that appear intermittently from childhood, namely abdominal pain, abdominal mass and jaundice. If the symptoms appear repeatedly, the possibility of diagnosis is greatly increased. Abdominal masses are the main cystic cases, and the onset age is early. Diagnosis can be made by palpation combined with ultrasound examination. Abdominal pain is the main symptom of spindle-shaped cases. In addition to ultrasound examination, ERCP or PTC examination is needed to make a correct diagnosis. There is no obvious difference between the two types of jaundice symptoms, and both can occur.

(1) Biochemical examination The determination of amylase in blood and urine should be used as a routine examination at the onset of abdominal pain, which is helpful for diagnosis. It can be suggested that this disease may be accompanied by pancreatitis. Or suggest that the confluence of pancreaticobiliary duct is abnormal, and high concentration of pancreatic amylase returns to bile duct and directly enters the blood through capillary bile duct, resulting in hyperamylasemia. At the same time, total bilirubin, 5' nucleotidase, alkaline phosphatase and transaminase all increased, and returned to normal in remission. Liver cells were damaged in the long-term course, but it was normal in asymptomatic cases.

B-ultrasound imaging has the advantages of intuition, tracking and dynamic observation. If the bile duct dilates due to obstruction, the position and range of liquid contents and the degree and length of bile duct dilatation can be correctly found out, and the diagnostic accuracy can reach over 94%. It should be used as a diagnostic method for routine examination.

(3) Percutaneous transhepatic cholangiography (PTC) is easy to succeed in the case of hepatobiliary dilatation, which can clearly show the intrahepatic bile duct and its flow direction, and determine whether there is bile duct dilatation and the extent of dilatation. When it is applied to jaundice cases, it can identify the etiology or obstructive site, observe the pathological changes of bile duct wall and its interior, and identify the cause of obstruction according to its image characteristics.

(4) Endoscopic retrograde cholangiopancreatography (ERCP) can directly inject contrast agent into bile duct and pancreatic duct through nipple opening intubation with the aid of duodenoscope, find out the expansion range and obstruction position of bile duct, and show the length and abnormality of common duct of pancreaticobiliary duct.

(5) Gastrointestinal barium meal examination showed that the duodenum shifted to the left and front, and the duodenal frame was enlarged, showing an isolated impression. Its diagnostic value has been replaced by ultrasound examination.

(6) Injecting contrast agent directly into the common bile duct during intraoperative cholangiography can display all the images of intrahepatic and extrahepatic bile duct system and pancreatic duct, and understand the degree of intrahepatic bile duct dilatation and the reflux of pancreatic duct, which is helpful for the choice of operation and postoperative treatment.

Generally, the above inspection methods include ultrasonic examination and biochemical determination first. If the abdominal mass is palpated clinically, the diagnosis can be established. If the tumor is not palpable clinically and the diagnosis is doubtful by ultrasound, ERCP examination is needed. If limited by equipment and age, PTC inspection should be carried out and other inspection methods should be supplemented when necessary.