The color of normal bile is golden yellow, dark green, clear and without impurities. If the color of bile shows colorless and transparent, clinically it is called white bile, which is mainly caused by the absorption of bile pigment in bile after obstruction of gallbladder duct and the increase of mucus secretion by gallbladder mucosa, and a small number of patients with bile duct obstruction may also have white bile. If the color of bile is obviously deepened, brownish-black and thick, it is mostly seen in obstructive jaundice, such as cholangiocarcinoma, pancreatic head cancer and periampullary cancer. Not only will there be more obvious yellow staining of the skin, mucous membranes and sclera, but also thick tea-colored urine and clay-like stools. If the bile has a purulent change and there is turbid material in the bile, it is commonly seen in secondary biliary infections caused by bile duct stones, mainly due to gram-negative bacilli. The presence of bloody fluid in the bile often indicates the presence of biliary bleeding, which may be closely related to bile duct tumors and stones. Biliary hemorrhage is often cyclic, accompanied by abdominal pain and jaundice.