There are four main possibilities for occasional bowel bleeding: 1. Hemorrhoids, one of the common rectal perianal diseases, manifesting clinically as blood dripping from the anus after stool or blood on the surface of the stool, rarely with severe anal pain. 2. Malignant tumors of the rectum, manifesting as intermittent blood in the stool or black stool, accompanied by generalized wasting and other systemic symptoms. 3. Anal fissures, seen in patients with long-term constipation, manifesting as blood dripping from the anus after stool, accompanied by severe pain in the anus, and the pain can increase during defecation. 4. 4.Benign rectal tumors, such as rectal adenoma, can appear when the local capillaries are broken, the bleeding will be reduced and can stop on its own. When there is occasional blood in the stool, you should go to a regular medical institution for fiberoptic colonoscopy in time to clarify the site and cause of bleeding, so as to achieve early detection and early treatment to avoid serious clinical complications.