When defecating, there are small lumps protruding outward from anus with bleeding, sometimes dripping down, sometimes jetting out, the amount can be large or small, showing a certain periodicity, but no anal pain, mostly hemorrhoidal bleeding; Blood in stool occurs in the process of defecation or after defecation, the blood color is bright red, the blood and feces do not mix, dripping out or wiping the blood on the handkerchiefs, and there is a sharp pain in the anus after defecation, then the blood in stool caused by fissure is mostly anal fissure. Tumor, there is a typical characteristic of change of stool habit and trait. Rectal cancer, due to its low position, the blood in stool caused by it is most similar to hemorrhoidal bleeding. The blood in stool is bright red, attached to the surface of stool in the form of drops, but most of them are mixed with mucus and dark blood clots in blood or stool, accompanied by bad smell, persistent, accompanied by anorectal dropping and generalized emaciation in the late stage, with an increase in the number of stools, and constipation and diarrhea appearing alternately. Rectal polyps, children blood in the stool is mostly caused by this disease. Polyp-induced blood in the stool, blood color bright red, painless, blood and stool do not mix, some patients in the surface of the stool with grooves, polyp growth to a certain length can be out of the anus with the stool. Ulcerative colitis, dysentery and other diseases can also cause blood in the stool, this kind of colorectal inflammatory diseases caused by blood in the stool is mostly mixed with mucus or pus and blood in the stool, and accompanied by lower abdominal pain, fever, frequent stools and symptoms, such as acute and severe, more common in adults.