Black stool is mainly caused by bleeding inside the intestine, which is also known as black stool. Because some patients with enterocolitis have damage to the intestinal mucosa, such as bleeding or bleeding in the intestine, if the amount of bleeding is high, there will be black stools when the patient has a bowel movement. When there is blood in the intestine, the blood will be digested and absorbed in the intestine to produce black stool, and the degree of black stool varies depending on the amount of bleeding. If the bleeding is around 50mL, black stools are usually noticeable, but if the amount of bleeding continues to increase, the patient’s stools will be very black, such as tar-like. If the amount of bleeding continues to increase or the rate continues to accelerate, it is possible that the patient may pass dark red stools or bright red stools, etc.