I. Hemorrhoids: Blood in the stool usually occurs during or after defecation, in the form of dripping blood or jets, bright red blood, often with constipation. Anal fissure: blood is bright red, dripping out or blood after wiping with hand paper, and there is severe pain in the anus after stool. There is often constipation. Rectal and colon polyps: blood is bright red, painless, and blood does not mix with stool. Fourth, ulcerative colitis: often diarrhea, bleeding mixed with mucus or pus-blood stool, often accompanied by abdominal pain. Rectal cancer: often have diarrhea, pus and blood stool, blood is bright red or dark red, attached to the surface of the stool in the form of droplets; and accompanied by anorectal cramps. Among the many anorectal diseases that cause blood in the stool, the most likely to be misdiagnosed are internal hemorrhoids and rectal cancer. Clinically, 80% of patients with early stage rectal cancer have been misdiagnosed as internal hemorrhoids. Therefore, patients must not take the symptoms of blood in stool lightly, but go to regular hospitals for examination as soon as possible to confirm the diagnosis and treat the symptoms.