Blood in the stool can mainly indicate signs of a variety of gastrointestinal diseases and systemic diseases such as leukemia. 1. Digestive tract diseases: (1) Small bowel diseases: common intestinal tuberculosis, intestinal typhoid fever, hookworm disease, acute hemorrhagic necrotizing enteritis, small bowel tumors, intussusception, small bowel necrosis and so on. (2) Colon diseases: acute bacillary dysentery, schistosomiasis, ulcerative colitis, colon cancer, colon polyps and so on. (3) Diseases of rectum and anal canal: there are rectal and anal canal injuries, radiation proctitis, rectal polyps, rectal cancer, hemorrhoids, anal fissure and so on. (4) Vascular lesions: including intestinal hemangioma, capillary dilatation of the digestive tract and so on. (5) Upper gastrointestinal diseases: such as upper gastrointestinal ulcer, gastric cancer, esophagogastric fundus varices, etc. (2) Systemic diseases: leukemia, thrombocytopenic purpura, vitamin C deficiency, hemophilia, etc. are common. If you find unexplained blood in the stool, you should consult a doctor in time, complete the examination, make a clear diagnosis and then be treated accordingly under the guidance of the doctor.