Blood on the surface of stool may be due to anal fissure, hemorrhoids, intestinal tumors and other diseases. 1. Anal fissure: Patients may have anal fissure due to lesions or trauma around the anus. After the occurrence of anal fissure, due to the existence of wounds in the anus, the patient will have blood on the surface of the stool during bowel movement. Some patients may also experience strong pain in the anal area. 2. hemorrhoids: hemorrhoids in the rupture will also cause the surface of the stool with blood, but also accompanied by local itching and pain. Mostly seen in internal hemorrhoids, mixed hemorrhoids. 3. Intestinal tumors: intestinal tumors, such as rectal tumors, with the growth of the tumor, the tumor surface will be ulcerated, and when there is an ulceration, there will be blood on the surface of the stool when the patient is having a bowel movement. 4. Rectal polyps: When the surface of rectal polyps is scratched by dry and hard stools, resulting in bleeding, it can be manifested as blood on the surface of stool. Blood on the surface of the stool may also be due to proctitis and other diseases, the patient should go to the hospital in time for examination, to clarify the cause of the disease, and then follow the doctor’s instructions for treatment.