There are usually the following situations: 1, fresh blood: consider lower gastrointestinal bleeding, or anal, rectal, sigmoid, descending colon bleeding; 2, dark red or tarry stool: consider upper gastrointestinal bleeding; 3, a few drops of fresh blood on the surface of the stool: if accompanied by anal pain, can be considered as a result of anal fissure, may also be caused by ruptured hemorrhoids; 4, a large amount of blood: the appearance of stool shape as well as changes in bowel habits, and a large amount of blood. And a large amount of blood, or bleeding before defecation, can consider the occurrence of colorectal cancer and other tumors; 5, pus and blood in the stool: need to consider ulcerative colitis or Crohn’s disease; 6, black tarry stool: consider gastric ulcer or duodenal ulcer rupture bleeding, that is, upper gastrointestinal bleeding problems.