In the emergency department, there are often patients with unbearable abdominal pain, generalized chills, profuse sweating, pale face, bending over and pressing the hand to the heart fossa, and intermittent vomiting. The doctor asks for medical history, many have a history of cholecystectomy, conducts ultrasound examination of the upper abdomen, the liver is fine, and finds that the patient’s common bile duct is mildly dilated and a double light band can be seen at the lower end of the common bile duct, which turns out to be biliary ascariasis, and the doctor gives pain and antispasmodic drugs, and then gives fluids and other treatments before the symptoms are controlled. Some people ask, why is this so? Ascaris lumbricoides is one of the most common parasitic worms in the human body, and although it usually haunts the human intestinal cavity, it is also fond of drilling and prefers alkali to acid. When the environment in which the roundworm lives changes, such as when it is too hungry or cold, it will take advantage of the opening of the lower end of the common bile duct and burrow into the human bile duct, which will then cause severe epigastric cramps and become one of the common acute abdominal conditions in surgery. In normal people, before cholecystectomy, the intestinal opening of the bile duct is open and closed because of the presence of the gallbladder, while after cholecystectomy, the opening of the bile duct is continuously open, and the bile is alkaline, so it is easier for biliary roundworms to enter the bile duct and cause biliary colic, plus in the case of an empty stomach, the roundworms like to go in the direction of the duodenum where the bile duct opens, so it is easier for biliary roundworm disease to occur. This disease can cause biliary stones, and also acute pancreatitis, jaundice and cholangitis, which can be life-threatening if not treated in time. After gallbladder removal, the intestinal environment changes, so we routinely deworm the intestines before surgery to prevent the occurrence of biliary roundworms to biliary obstruction in the near future after gallbladder surgery. After patients are discharged from the hospital, they often forget to check the stool for roundworm eggs and fail to carry out deworming treatment in time, resulting in the occurrence of biliary ascariasis.