1) Causes of reflux Normal pyloric sphincter can prevent duodenal juice from flowing back into the stomach, and cholecystokinin and gastrin can adjust the tension of pyloric sphincter. Under normal circumstances, the balance of the two hormones makes the pyloric dilator contract properly and bile reflux does not occur. In recent years, it has been found that normal people also have a small amount of reflux, but this "physiological" reflux will not cause lesions. The reasons are as follows: ① any operation that reduces or destroys pyloric function. Subtotal gastrectomy and jejunostomy are the most common causes of bile reflux gastritis, and pyloroplasty or pylorotomy and gastroduodenostomy also cause bile reflux. ② organic lesions of pylorus, such as pylorus deformation caused by ulcer. ③ After cholecystectomy, the bile bed disappears, bile continues to enter the duodenum on an empty stomach, and bile easily returns to the stomach, so the incidence of reflux gastritis increases after cholecystectomy. ④ Under the condition that there is no history of gastric surgery and the pyloric structure is intact, smoking, aspirin and other drugs can cause hormonal endocrine regulation disorder or change of gastroduodenal movement type (duodenal reverse peristalsis), and in severe cases, it can cause spontaneous bile reflux and even reflux gastritis.