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. The ERCP technique performed 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 difficult Bi-II major gastrectomy, but there are no reports on how to perform ERCP after complex gastrointestinal surgery in China. ERCP cannot be performed with conventional duodenoscopy, and the risk of re-operation for such patients with pancreaticobiliary diseases is high and difficult, so it is worth exploring how to perform effective endoscopic minimally invasive treatment. The Gastroenterology Pancreaticobiliary Disease Group has creatively used a combination of two endoscopes in these patients, i.e., the diagnostic small bowel scope is first inserted to the lesion site, then the cuff is retained and the small bowel scope is withdrawn (the length of the intestinal tube is shortened because it is tightly compressed on the external trocar), and then a shorter colonoscope is used to reach the lesion site, so that the conventional ERCP accessory can be extended to the head end of the colonoscope. Further intubation and lithotripsy are then performed. This method has not been reported in China or abroad. Its novelty and value lies in the use of relatively inexpensive and easily available equipment for minimally invasive treatment of patients with pancreaticobiliary disease after complex gastrointestinal surgery, which solves patients’ practical problems.