There are four types of blood in the toilet: first, hemorrhoids, one of the common rectal perianal diseases, clinical manifestations are mostly blood dripping from the anus after the stool or stool mixed with fresh blood, and rarely occurs severe anal pain. Second, rectal malignant tumor, manifested as intermittent blood in the stool or black stool and accompanied by changes in stool characteristics, such as diarrhea or unformed stool. Third, anal fissure, common in patients with long-term constipation, manifested as post-poo anal drip blood accompanied by severe anal pain and the pain can increase during defecation. Fourth, benign rectal tumors such as rectal adenomas or polyps, when the local capillaries break can appear blood in the stool, the bleeding volume is reduced and can mostly stop on its own. When there is blood in the toilet, you should go to a regular medical institution for fiberoptic colonoscopy in time to clarify the site and cause of bleeding, early detection and early treatment to avoid serious clinical complications.