Blood in stool of bowel cancer patients is not continuous, but mostly intermittent. Blood in stool is mainly caused by tumor surface breaking and bleeding, so the tumor surface will break within a period of time, but the human body has healing effect, that is, after a period of time, the tumor surface breaking will heal partly by itself and bleeding can stop by itself. Therefore, the patient should have blood in stool intermittently or occasionally with blood in stool, usually not every time when he/she has a bowel movement. It may be accompanied by increased frequency of stool and diarrhea. Therefore, when patients find blood in stool, they should do colonoscopy, CT and other related examinations in time.