The reason for anal bleeding during stool is particularly varied: 1. The more common is mixed hemorrhoids, especially internal hemorrhoids bleeding, which usually lead to swelling of the hemorrhoid nucleus and rupture of the hemorrhoid vein when it is difficult to defecate or when the abdominal pressure increases, resulting in bleeding. 2. Anal bleeding during stool may also be anal fissures, where dry stool can easily damage the skin of the anal canal leading to fissures, which can appear with blood on the surface of the stool. 3. Long-term stool stimulation can easily lead to rupture of the mucosal vessels on the surface of the polyps, resulting in anal bleeding. Another reason is the history of trauma, if there is a history of trauma or foreign body invasion of the rectum and anus, it is possible to damage the rectal mucosa, resulting in blood vessel rupture and cause anal bleeding during stool. Therefore, there are many reasons for anal bleeding during stool, so it should be combined with medical history, physical examination and, if necessary, anoscopy or colonoscopy to clarify the cause or location of bleeding.