Fecal occult blood test may be positive. Carcinoembryonic antigen (CEA) and glycoconjugate antigen CA-199, CA-50, CA-242 in serum and bile have a certain positive rate in cholangiocarcinoma and can be used as an aid to diagnosis and postoperative follow-up. 1.Increased direct bilirubin laboratory examination shows the manifestation of obstructive jaundice, and elevated serum total bilirubin and direct bilirubin shows the manifestation of cholestatic jaundice. 2, the manifestation of secondary liver damage in long-term biliary obstruction, there can be secondary liver function damage, ALT and AST mildly elevated is the manifestation of secondary liver damage. The decrease in total serum protein and albumin is a manifestation of malnutrition and liver damage. Prolonged prothrombin time is a sign of biliary obstruction and secondary liver damage. γ-GT and alkaline phosphatase are increased. ALP and γ-GT are elevated when jaundice does not appear in the early stage, suggesting biliary obstruction. 3. blood tests More than half of the patients have a blood leukocyte count of 8×109/L or higher, if significantly elevated, suggesting biliary tract infection. 61% to 70% of patients may have varying degrees of Hb reduction. The main purpose of imaging examination is to diagnose the site of obstruction, determine the nature of possible lesions and estimate the extent of lesions and the relationship with surrounding tissues and organs. 4.B ultrasound Among many imaging examinations, B-mode ultrasound is the preferred diagnostic method. Real-time ultrasound examination has a high diagnostic rate for the site and degree of bile duct obstruction, and the detection rate of bile duct dilatation can reach more than 95%, which is the preferred examination. Ultrasound-guided fine-needle aspiration cytology is a simple, safe and effective method. The probe of endoscopic ultrasound (EUS) is separated from the biliary system by only one layer of the intestinal wall, which excludes interference such as overlapping of the thoracoabdominal wall and the gastrointestinal tract, and allows clearer observation of the biliary tract. IDUS (intraductal-ultrasonography) uses a miniature ultrasound probe to scan directly into the bile duct through the PTC sinus tract or ERCP route, which completely excludes the interference of obscuring bile duct tissues and provides clearer images than EUS. The accuracy rate of judging whether the pancreas and duodenum are involved is 100%. 5.CTCT is still a routine examination method, which can show the dilatation of bile ducts inside and outside the liver. Sometimes thickening of the bile duct wall, irregular narrowing of the lumen, involvement of the enlarged gallbladder as well as surrounding tissues and organs and blood vessels, or small nodular shadow protruding from the bile duct wall into the lumen are seen. It provides a basis for staging the lesion and the possibility of surgical resection. The spiral CT angiography (SCTA) technology can complete a series of thin-section vascular images in a very short time, and the three-dimensional vascular reconstruction technology also provides important information for understanding the relationship between tumor and blood vessels and whether the tumor in the liver portal can be removed. 6.Echo-endoscopy (EUS) EUS is a new diagnostic tool combining two imaging techniques: endoscopy and intracavitary ultrasound. The bile duct wall can be divided into three layers under EUS: the first layer of high echogenicity is rather mucous membrane plus interface echogenicity; the second layer of low echogenicity is smooth muscle fiber and fiber elastic tissue; the third layer of high echogenicity is loose connective tissue plus interface echogenicity. The detection rate of bile duct cancer is 96% with hypoechoic or hyperechoic masses under EUS, and it can indicate the size of the mass and the presence of lymph node metastasis. 7.Percutaneous transhepatic cholangiography (PTC) is the basic means for bile duct tumor diagnosis, which can show the location and scope of tumor and the confirmation rate is over 90%. PTC is suitable for patients with dilated intrahepatic bile ducts, and the catheter can be left in place for bile drainage (PTCD) after the operation. PTC is feasible for patients with dilated intrahepatic bile ducts as shown by ultrasound and CT examination, which can not only directly show and clarify the location of the tumor, the upper edge of the lesion and the extent of involvement of the hepatic ducts. This examination is important for preoperative determination of surgical plan, and its correct diagnosis rate can reach more than 90%. However, this test is invasive and may cause bile leakage and cholangitis. To avoid these complications, it is best to perform the test one day before the procedure, drain the contrast as much as possible after the test, and be ready to perform the procedure.