Fresh blood in the stool may be caused by anal fissure, internal hemorrhoids, rectal polyps, intestinal cancer and so on. 1. Anal fissure: the stool is relatively dry and hard, it is not easy to discharge when defecating, too much force, resulting in the anal edge of the skin is propped up and cracked, bleeding bright red blood, usually accompanied by intense pain in the anus. 2. internal hemorrhoids: the nature of internal hemorrhoids is a vascular mass surface has a lot of tiny capillaries, defecation abdominal pressure increases, these capillaries pressure will also increase, triggered by rupture, out of bright red blood, most of them will not be accompanied by pain, only internal hemorrhoids prolapse caused by incarceration, can be accompanied by pain, anal swelling. 3. Rectal polyps: when polyps grow in the rectum near the anus, the friction caused by fecal discharge leads to erosion of mucous membrane and the discharge of fresh blood. 4. Bowel cancer: the invasion of cancer cells to intestinal tissues causes erosion and bleeding, tumor corruption and erosion, which will lead to blood in stool, accompanied by symptoms such as emaciation and anemia. It is recommended to consult the doctor in time, do detailed examination, clarify the cause of the disease and give appropriate treatment.