The characteristics of GI bleeding stools are closely related to the amount of bleeding: 1) Very small amount of bleeding, in which case the stool is not abnormal and is completely normal to the naked eye. 2) When the amount of bleeding reaches a certain level, black stools and tarry stools may appear, especially when there is a small amount of bleeding in the upper gastrointestinal tract, which should be excluded due to the consumption of food and drugs that make the stool black. 3, when the amount of bleeding and more, there will be blood in the stool and direct blood in the stool, mainly fresh blood stool, may also be clotted, the final want to confirm the diagnosis or according to the stool routine.