Pus and blood in stool has the following reasons: 1. Ulcerative colitis: the cause of the disease is not clear and the poor autoimmunity has a certain relationship. The main symptom is pus and blood in the stool, there are also symptoms of abdominal pain, the condition will be repeated, and over time there will be general weakness, weight loss and other symptoms. 2, malignant intestinal cancer: in addition to cause pus and blood in the stool, there are symptoms such as fatigue, weight loss too fast. 3, dysentery: generally eat contaminated food infected with germs. In addition to the symptoms of pus and blood in the stool, there is abdominal pain, anal burning, fever and other symptoms. 4, chronic schistosomiasis: the main symptom of pus and blood in the stool, sometimes there will be a situation similar to dysentery, and dysentery, and over time there will be poor health, anemia and other symptoms. To immediately go to the hospital to do colonoscopy and other tests, after a clear cause of the symptomatic treatment.