There are many causes of anal bleeding during stool, which should be combined with medical history and physical examination and, if necessary, anoscopy or colonoscopy to clarify the cause. First, if there is a history of trauma or foreign body invasion into the anorectum, it is possible that the foreign body may puncture the rectal mucosa and cause bleeding. Second, if you have mixed hemorrhoids, the nucleus of the hemorrhoid tends to swell when you have difficulty in defecating or when the abdominal pressure increases, and the vein ruptures, causing bleeding. Thirdly, dry stool can easily damage the skin around the anus and lead to fissures, and blood will be carried on the surface of the stool when wiping it. Fourth, in the case of rectal polyps, rectal adenomas or malignant tumors, the stimulation of long-term stool can cause the rupture of the submucosal vessels of the rectum, resulting in bleeding. Therefore, there are many reasons for blood in the stool, which should be combined with examination, and if necessary, colonoscopy or gastroscopy should be performed to clarify whether there are gastric and duodenal ulcers, or small intestine capsule endoscopy to observe whether there are small intestine polyps or diverticula. Because these diseases may cause anal bleeding when relieving stool.