Blood inside the stool may be caused by the following conditions: First, anal fissure caused by dry stool, the main symptom is blood dripping when defecating or blood after wiping, blood attached to the surface of the stool, accompanied by a strong tearing pain when defecating. Second, severe attacks of internal hemorrhoids, the main symptom is blood in the stool, bright red blood, but can not be mixed with the stool, accompanied by pain, especially in the case of serious hemorrhoids, the amount of bleeding will increase, the need for timely treatment, if left unattended may appear anemia. Third, the bleeding symptoms caused by colon and rectal lesions, and possibly peptic ulcers, colitis, it is recommended to go to the hospital anorectal specialist for examination, and then timely treatment accordingly.