There are many diseases that can cause bleeding in the stool, mainly internal hemorrhoids, anal fissures, polyps in the colorectum, anorectal cancer, ulcerative colitis and so on. Internal hemorrhoids usually have bright red blood in the stool, and the amount of blood is relatively large, which can be in the form of dripping blood in the stool, or in severe cases, jet-like bleeding, sometimes accompanied by blood clots. In anal fissures, the blood in the stool is usually smaller in volume and accompanied by severe pain. In colorectal polyps, the blood in the stool is bright red but does not hurt, and the blood does not mix with the stool. In colorectal cancer, blood in stool is usually dark red blood, accompanied by general wasting, weakness, and changes in stool habits, such as a sudden increase or decrease in the number of stools, and changes in the shape of stools, which can be clearly diagnosed by e-colonoscopy. In ulcerative colitis, blood in the stool is usually accompanied by mucus or pus-blood stool, which also needs to be diagnosed by e-colonoscopy.