There are many reasons for anal bleeding, the first one, this situation should be asked medical history, whether there is a history of foreign body invasion into the anorectum, if the patient exists hit, fall, foreign body invasion into the anus, will find some traumatic fissures in the perianal area, if the invasion of blood vessels, will lead to anal bleeding. The second, whether previous hemorrhoidectomy or other anal surgery, after anal surgery, due to incomplete intraoperative hemostasis, postoperative ligature line off, and sometimes dry stool easily stimulate the trabecular blood vessels, causing bleeding. The third common cause of anal bleeding may also be mixed hemorrhoids, especially bleeding caused by internal hemorrhoids, long-term constipation or dry stools, eating chili peppers or drinking a lot of alcohol, resulting in swelling of the hemorrhoid nucleus and rupture of the hemorrhoid vein, blood is usually not mixed with feces. The fourth common cause of anal bleeding may also be rectal polyps, rectal adenomas, and even rectal malignancies can also cause bleeding. Therefore, there are many causes of anal bleeding, which should be combined with medical history, rectal examination and, if necessary, colonoscopy to clarify the cause and location of bleeding.