Stool bleeding it has particularly many causes: the first, there may be internal hemorrhoids, internal hemorrhoids are varicose vein masses, if the stool is dry or abdominal pressure increases, it is generally easy to cause the hemorrhoid nucleus to swell during stool, hemorrhoid vein rupture and cause bleeding. Second, it may be anal fissures, such as dry stools that tend to damage the skin of the anal canal leading to fissures, which tend to cover the surface with blood when defecating. Third, blood in the stool, there may also be rectal polyps or rectal adenomas, long-term stool irritation is prone to rupture the mucosal vessels on the surface of the polyps and lead to bleeding. Fourth, there may be malignant tumors of the rectum and colon, which, if prolonged, tend to invade the mucosa and submucosal blood vessels and cause bleeding. There is also ulcerative colitis, rectal mucosal co-infection, which can locally cause some blood vessels to rupture resulting in stools with pus and blood. Therefore, there are many causes of blood in the stool, so it should be combined with medical history and physical examination, and if necessary, anoscopy or colonoscopy to clarify the site and cause of bleeding.