Indications for gastroscopy: 1.Suspected esophagitis, esophageal ulcer, tumor, stricture, esophageal hiatal hernia and esophageal varices; 2.Suspected acute and chronic gastritis, gastric ulcer, gastric tumor, gastric cancer and duodenal bulb ulcer, bulbitis, bulb deformation, diverticulum, cancer, duodenal papillary lesion and foreign body in the upper gastrointestinal tract, all can be diagnosed by gastroscopy. Gastroscopy is feasible for the following patients: 1. upper abdominal discomfort, suspected to be upper gastrointestinal lesions that cannot be clinically diagnosed; 2. unexplained upper gastrointestinal bleeding; 3. lesions requiring follow-up diagnosis such as ulcers, atrophic gastritis, gastric precancerous lesions, etc.; 4. those requiring gastroscopic treatment. Preparation before gastroscopy: 1. routine blood tests, hepatitis B five items, coagulation four items, electrocardiogram, etc. are required before gastroscopy; 2. 8 hours of fasting before gastroscopy; 3. the patient provides a towel.