The causes of constipation and bleeding in poop may be hemorrhoids, anal fissure, rectal polyps, rectal cancer and so on. 1. Hemorrhoids: a common anal and intestinal disease, mainly manifested as painless bleeding during defecation, itching and pain around the anus, anal swelling and other symptoms, which may be accompanied by constipation, thus manifesting as constipation and bleeding in poop. 2. Anal fissure: small ulcers formed after fissure of the anal canal skin below the dentate line. Its main manifestation is perianal pain, aggravated during defecation, accompanied by constipation, bleeding during defecation and other symptoms, which can also manifest as constipation and bleeding during poop. 3. Rectal polyps: most patients with rectal polyps have no obvious symptoms, and part of the population may show painless blood in stool, change of bowel habit, diarrhea or constipation, polyp prolapse and other symptoms. 4. Rectal cancer: refers to malignant tumors occurring in the rectum, mainly manifested as change of bowel habit, change of stool trait, blood in stool, constipation or diarrhea, and anal falling sensation and other symptoms. There are many other causes of constipation and poop bleeding, which should be taken seriously, timely consultation, identify the cause of the disease, and follow the doctor’s instructions for further treatment or therapy.