The so-called blood in stool is caused by many reasons, such as hemorrhoids, anal fissure, ulcerative colitis, rectal polyps, intestinal tumors, etc. Hemorrhoids: usually manifested as blood in stool or bleeding after stool, accompanied by pain, moisture and other manifestations. 1. Hemorrhoids: usually manifested as feces with fresh blood or bleeding after stool, accompanied by pain, moisture and other manifestations, mostly due to dry stool force, constipation, squatting and other causes of blood in the stool. 2. Anal fissure: if the patient’s stool is too dry, in the process of defecation, squeezing to the anus, it will lead to partial or total cracking of the anal canal skin, causing bleeding symptoms, the blood color is bright red, and it occurs mostly in the anus at 6 points and 12 points. 3. Ulcerative colitis: it is often manifested as mucus, pus and blood stool, accompanied by abdominal pain, diarrhea, change of stool properties and other symptoms. 4. Rectal polyps: often manifested as blood in the stool, anal mass prolapse and other symptoms, some patients may also have diarrhea, constipation, abdominal pain and other symptoms. 5. Intestinal tumor: in addition to blood in stool, there are also changes in stool characteristics, such as thinning of stool, emaciation, etc. If there are symptoms of blood in stool, the patient may have symptoms of diarrhea, constipation and abdominal pain. If you have symptoms of blood in stool, you should go to the hospital in time for relevant examination, so as to make a clear diagnosis and give reasonable treatment as soon as possible.