Diseases such as anal fissure, hemorrhoids, colorectal cancer or polyps, enteritis or Crohn’s disease can cause a mixture of stool and blood. 1. Anal fissure: Bleeding from anal fissure is caused by dryness of stool and rupture of anal canal stimulated by defecation, so there will be blood in stool. 2. Hemorrhoids: Hemorrhoids have the symptom of blood in stool, and the blood often adheres to the surface of feces. 3. Colorectal cancer: there may be no bloody stool in the early stage of the lesion. When the tumor gradually increases and infiltrates into the deep part, it may be accompanied by bleeding, even hemorrhage, and the blood is often mixed with feces. 4. Rectal polyps: small polyps usually seldom bleed, but when the polyps increase in size and the surface of mucous membrane is damaged, they may be accompanied by bleeding, which is usually eliminated with feces, but the bleeding is less, and it may be repeated at the same time. 5. Ulcerative colitis and Crohn’s disease: this disease is most common in the colon, especially the rectum and sigmoid colon. The lesions are predominantly submucosal and submucosal, and mucopurulent bloody stools are common. Usually bleeding from anal and rectal lesions is mixed with stool, and the blood is usually adherent to the stool. Colonic lesions, on the other hand, tend to result in adequate mixing of stool and blood, but the two mix less adequately when the bleeding is heavy and the location of the bleeding is close to the rectum. Therefore, the appearance of stool and blood mixing, you should go to the hospital, a clear diagnosis to be treated accordingly.