ERCP is the first choice for the treatment of bile duct stones. After treatment, doctors often place a nasobiliary drainage tube. The nasobiliary drainage tube is equivalent to placing one end of a plastic tube in the bile duct and the other end through the duodenum. , Stomach, mouth, nostril drainage to the body, the main purpose is to drain bile. Because after the operation in the bile duct, edema may occur at the lower end of the bile duct, including the opening of the duodenal papilla, which will lead to poor bile drainage, and acute cholangitis will occur once the bile drainage is poor. The purpose of placing the nasobiliary duct is to ensure that bile can flow out when there is edema near the surgical wound within a short time after the operation, so that postoperative acute cholangitis will not occur. Another use is that the patient suffers from acute cholangitis. In this case, the risk of taking stones in one stage is relatively high. Doctors often place a nasobiliary drainage tube in the bile duct to drain the infected dirty bile, etc. Removal of stones after the bile has cleared or the infection has fully recovered makes the procedure safer and the patient recovers faster. The drainage tube is very thin, the patient does not feel obvious pain, and the drainage tube is not placed for a long time, usually not more than a week.