Gastroscopy is a common diagnostic method for gastric diseases, but it is an invasive test and requires anesthesia for the patient. The patient’s blood count should be checked before the examination, and if the patient’s hematocrit is found to be too low, gastroscopy should be avoided to avoid accidents during anesthesia. Gastroscopy may require biopsy or removal of gastric polyps, so the coagulation function of the patient should be known before the examination to avoid coagulation disorders after the removal. In elderly people, an electrocardiogram should be performed to avoid the anesthetic affecting the heart during gastroscopy, and in patients with cirrhosis of the liver, an abdominal ultrasound should be performed to understand the fluid in the abdominal cavity and the presence of other infections.