Upper gastrointestinal bleeding occurs when the amount of upper gastrointestinal bleeding reaches 200-300ml. Upper gastrointestinal bleeding is commonly caused by ruptured fundic veins, gastric perforation, gastric ulcer, gastric cancer, etc. These diseases can cause damage to the blood vessels in the stomach wall, and therefore bleeding can occur. When the amount of bleeding in the upper gastrointestinal tract is relatively small, the blood enters the lower gastrointestinal tract along with the food, so there is no vomiting of blood. However, when the bleeding volume exceeds 250 ml, the blood cannot be emptied through the pylorus in time, so the phenomenon of vomiting blood will occur, accompanied by black stools. In some people, the amount of gastrointestinal bleeding can be as large as 1000ml, which makes the patient not only vomit blood, but also suffer from hemorrhagic shock, which requires timely resuscitation treatment, otherwise it will pose a threat to the patient’s life.