There are several possible reasons for blood in the stool: 1, anal fissure or hemorrhoids. Anal fissures or hemorrhoids bleeding usually appear at the end of the stool bleeding or dripping blood, blood color is relatively bright red and separate from the stool, mostly seen in dry stool or constipation patients. 2, digestive bleeding. Peptic ulcer or portal hypertension and other causes of gastrointestinal bleeding, the blood color is dark red, mixed evenly with the stool, serious blood stool. 3, intestinal infections caused by blood in the stool. Mostly seen in ulcerative colitis, bacillary dysentery and other intestinal diseases, can be manifested as pus and blood stools, need to be further through routine stool examination, colonoscopy to clarify the specific causes of bleeding and bleeding sites, and then targeted treatment.