In order to solve the problem of diagnosis and treatment of pancreaticobiliary diseases after complex gastrointestinal surgery, the Department of Gastroenterology has applied balloon-assisted endoscopic technology to perform minimally invasive endoscopic treatment for patients who have developed or recurred pancreaticobiliary system diseases after complex gastrointestinal surgery (e.g., biliary-intestinal anastomosis, WHIPPLE) who have come to our hospital in the past two years, and has accumulated more than 50 cases with a success rate of more than 90%. The anatomical structure of the intestinal tract is obviously changed after complex surgery of the digestive tract, so the conventional endoscope cannot complete the ERCP diagnostic operation due to the length and/or angle problems. The Gastroenterology Department first uses a single-balloon small intestinal scope (adapted from our double-balloon small intestinal scope using only the cuff balloon) to insert the scope to the lesion site (postoperative biliary-intestinal and pancreatic-intestinal anastomosis), then withdraws the small intestinal scope while retaining the cuff, and then inserts a thin diameter colonoscope through the trocar to the lesion site, and completes ERCP through the operating jaws of the colonoscope. ERCP technique through duodenoscopy is currently However, the application of this technique is often difficult in patients after gastrointestinal surgery. There are a few reports on how to perform ERCP in patients after the more difficult Bi-II major gastrectomy, but there are no reports on how to perform ERCP after complex gastrointestinal surgery. ERCP cannot be performed using conventional duodenoscopy, and the risk of reoperation is high and difficult for such patients with pancreaticobiliary diseases, so it is worth exploring how to perform effective endoscopic minimally invasive treatment. In recent years, there are a few reports of ERCP operation using small intestinal microscope, but therapeutic small intestinal microscope and its accompanying ERCP accessory are needed, which are expensive and difficult to obtain because of the infrequent use of such equipment. (The length of the intestinal tube is shortened because it is tightly compressed on the external trocar), and then a shorter colonoscope can be used to reach the lesion, so that the conventional ERCP attachment can be extended to the head end of the colonoscope and further intubation and lithotripsy can be performed. This method has not been reported in China or abroad. Its novelty and value lies in the use of relatively inexpensive and readily available equipment for the minimally invasive treatment of patients with pancreaticobiliary disease after complex gastrointestinal surgery, which solves patients’ practical problems.