There are many causes of fecal bleeding such as: internal hemorrhoids, anal fissures, rectal polyps, ulcerative colitis `radioactive proctitis, rectal cancer, etc. Internal hemorrhoids: Blood in stool is the main symptom of internal hemorrhoids, the bleeding is mostly intermittent, the color of the blood is bright red, the way of bleeding is mostly shown as dripping blood, sometimes the stool with a little blood, or even jet bleeding, or pure blood without stool, the blood in stool is usually not accompanied by pain, the amount of bleeding is more or less, serious cases can have heavy bleeding, resulting in hemorrhagic anemia, the bleeding is mostly due to fecal abrasion of the mucosal surface of the hemorrhoid nucleus, or injury to the submucosal vessels, or due to constipation during defecation. The reason for bleeding is that the feces rubs the mucosal surface of the hemorrhoid nucleus, or damages the submucosal vessels, or causes excessive pressure in the blood vessels due to constipation and bleeding. Anal fissures: Anal fissures are often accompanied by significant pain and periodic pain, and examination may reveal longitudinal fissures or ulcers in the anal canal. Rectal polyps: Symptoms of both rectal polyps and internal hemorrhoids can be seen as painless blood in the stool and limited elevation of the mucosa, but rectal polyps are most often seen in children and occur at a relatively higher location than internal hemorrhoids, and polyps can be tipped and are often round or oval, while internal hemorrhoids are localized elevations. Rectal cancer: Rectal cancer blood in the stool is mostly dark red or jam-colored, but it can also be pus and blood, sometimes mixed with stool. It is often accompanied by symptoms such as increased blood in stool, anal drop and significant weight loss. Rectal swelling can be palpated by anorectal diagnosis, with unsmooth surface, irregular shape, hard texture and adhesion to surrounding tissues, which is not easy to move when pushed. The diagnosis can be confirmed by taking a biopsy for pathology. Ulcerative colitis: blood in the stool is often pus and blood mucous membrane stool, and is accompanied by diarrhea, abdominal pain, increased frequency of stool, wasting, anemia and other symptoms. In a few patients, the rectum is involved and causes urgency. Radiation proctitis: Blood in the stool is mucus and blood or blood in the stool, which is seen after radiation therapy for pelvic cancer.