Blood in the stool is the most common symptom of anorectal disease. According to the bleeding site, the amount of bleeding and the speed of bleeding and blood in the intestine stay time, the same, its blood and stool color also varies. If the stool with fresh blood, it is definitely a lesion of the colon and anal canal. The following conditions can appear as painless bleeding after stool: 1. Hemorrhoids: The main manifestation is blood in the stool and the prolapse of hemorrhoid mass. Blood in the stool is characterized by painless intermittent post-poo bleeding. If thrombosis, infection and impaction occur, it can be accompanied by severe anal pain, but if none of the above is present, there is no pain. 2, rectal polyps: bleeding in the stool or bleeding after defecation, generally the amount of blood in the stool is not much, not mixed with feces, blood attached to the surface of the feces, appearing red. The polyp occurs above the dentate line and is innervated by the autonomic nerve and is painless, while the polyp below the dentate line is innervated by the internal nerve of the pubic area and is painful if it is sensitive to pain. 3.Bacterial dysentery: one of the causes of blood in the stool, small amount, often mixed with stool, pus and blood stool, bright red, more frequent stools, with a sense of urgency, may be accompanied by fever, diarrhea, nausea, vomiting, etc. 4, rectal cancer: mostly seen in middle-aged and elderly people, intermittent or repeated episodes of blood in the stool, gradually aggravated. The surface of stool can be mixed with mucus, pus and blood, and the shape of stool is changed. Generally, bleeding after stool with bright red color and no pain is mainly considered as the above situation. It is recommended to consult a doctor in time to do colonoscopy to find out the cause of blood in stool and treat it symptomatically to avoid excessive blood loss and damage to health.