Obstructive jaundice is jaundice due to obstruction or stricture of the bile ducts within or outside the liver and generally requires surgical treatment, also known as “surgical jaundice”, which can be caused by various benign or malignant lesions of the biliary tract and is characterized by dilatation of the bile ducts at the upper end of the obstruction. When bile duct obstruction occurs, compensatory dilation of the biliary system may occur to relieve the elevated pressure in the bile duct, followed by scleral or cutaneous jaundice. Therefore, the determination of “biliary tract dilatation” is the key to identify the presence or absence of biliary tract obstruction. Ultrasound is the most convenient, rapid, inexpensive, and non-invasive imaging method to examine the biliary tract for dilatation, with an accuracy rate of more than 90%. CT and MRCP are also non-invasive and can provide clinicians with an objective basis for biliary tract disease, and are often used to further define the location of obstruction. Although percutaneous hepatic puncture cholangiography (PTC) and transduodenoscopic retrograde cholangiopancreatography (ERCP) can help determine the presence or absence of bile duct dilatation, they are generally not used as routine examinations due to their invasive nature, and are used to further define the site and nature of obstruction and the treatment of certain diseases. In terms of laboratory tests, elevated serum direct bilirubin and total bilirubin can be found, especially the elevation of direct bilirubin is clearly correlated with the severity of biliary obstruction, and transaminases can parallel the elevation of bilirubin, suggesting different degrees of hepatocyte damage. Bile acids, alkaline phosphatase and alanyl transferase are also sensitive indicators for determining biliary obstruction and cholestasis, but in patients with active hepatitis combined with biliary obstruction, it is difficult to distinguish between medical and surgical jaundice from serum enzymatic tests alone. Briefly, in general, the presence or absence of bile duct dilatation in jaundiced patients can be detected by ultrasound examination in primary units, and if dilatation is present, further consultation in surgery is recommended.