How to assess the amount of gastrointestinal bleeding? If the amount of bleeding is >5ml, the stool test result will show positive for occult blood in the stool. If the amount of gastrointestinal bleeding is more than 50 ml, the stool may become black in color, which is usually referred to as black stool. If the amount of bleeding in the stomach is 300 ml or more, vomiting of blood and black stools may occur. If the bleeding volume is >1000ml, because the human blood volume is 4000ml, which is greater than 20% of the human blood volume, it is called gastrointestinal hemorrhage. In case of gastrointestinal hemorrhage, the patient may show some signs of insufficient blood circulation, such as dizziness, weakness, cold sweat, and in severe cases, loss of consciousness and urinary and fecal incontinence. This is a life-threatening condition that needs to be treated as a matter of urgency. Blood and fluid transfusion must be administered immediately to maintain the volume of blood circulation and save the patient’s life.