Direct bilirubin is also known as conjugated bilirubin. When indirect bilirubin is transported to the liver with blood, it is rapidly taken up by hepatocytes and transformed into direct bilirubin in hepatocytes through conversion and metabolism, and then secreted into the capillary bile ducts, entering the gallbladder with bile and entering the intestine according to the digestive needs, any problem in the middle can cause an increase in direct bilirubin for the following reasons: 1. Due to congenital or acquired hepatocyte (such as viral hepatitis, drug-related liver disease, pregnancy, alcoholic liver disease, etc.) bile excretion disorders, so that direct bilirubin can not be well discharged to the capillary bile ducts, resulting in direct bilirubin into the blood, direct bilirubin in the blood is elevated. 2, various causes of biliary obstruction, such as biliary stones, roundworms, tumors, inflammation and surgical trauma caused by bile duct stenosis, bile discharge into the intestine is blocked, the obstruction of the upper bile ducts, there is a large amount of bile stagnation, bile duct expansion, pressure rise, bile through the rupture of small bile ducts and capillary bile ducts and flow into the tissue interstitial and blood sinus, causing the rise of direct bilirubin in the blood. Elevated bilirubin can cause jaundice, which can be divided into occult jaundice and overt jaundice depending on the degree of bilirubin elevation. Regardless of the cause of bilirubin elevation, we should actively search for the cause and provide symptomatic treatment to reduce the damage caused by bilirubin elevation.