Nine diseases causing hematochezia: 1. Hemorrhoids or anal fissure and anal fistula are generally bright red in color, and they are not mixed with feces and contain no mucus. It is characterized by bleeding after defecation, especially when the stool is hard. 2. Bacillary dysentery stool is often purulent, a small amount at a time, often accompanied by urgency; The chronic phase is intermittent mucus and purulent bloody stool. 3. Amoebic dysentery is mostly jam-like, or dark red, with a large amount, often accompanied by purulent mucus. Most patients have fever, abdominal distension, abdominal pain and acute diarrhea. 4. Schistosomiasis has a history of contact with epidemic water, often manifested as chronic diarrhea, purulent stool or bloody stool. 5. Ulcerative colitis stools are generally mucus purulent bloody stools, and severe cases can be bloody watery stools. 6. Intussusception discharges mucus and bloody stool, often without stool. 7. Rectal cancer. When the stool becomes thin, accompanied by mucus and pus, the possibility of colon cancer should be suspected. 9. When rectum, colon polyp rectum, S-shaped colon or descending colon polyp, it indicates that fresh blood is attached to feces. These people should be wary of bloody stools.