Blood in the stool even if blood. The causes of blood in stool can be seen in upper gastrointestinal diseases such as esophageal cancer; lower gastrointestinal diseases such as intestinal tuberculosis; systemic diseases such as leukemia and so on. 1. Upper gastrointestinal diseases ①Esophageal diseases: such as esophageal cancer, esophageal foreign body, rupture of esophagogastric fundus varices, and mucosal tear of esophageal cardia. ② gastroduodenal diseases: acute erosive hemorrhagic gastritis, peptic ulcer, gastric cancer. Diseases of liver, gallbladder and pancreas: pancreatic cyst, pancreatic abscess, gallbladder cancer, bile duct cancer, pancreatic pseudocyst, etc. 2. Diseases of lower gastrointestinal tract Diseases of small intestine: Crohn’s disease, intestinal tuberculosis, intestinal typhus, acute hemorrhagic necrotizing enteritis, hookworm disease, small intestinal polyps, intestinal ulcer, intussusception, etc. ② colon diseases: ulcerative colitis, colonic diverticulitis, colon cancer, colon polyps, acute bacillary dysentery, amoebic enteropathy, schistosomiasis, ischemic colitis, etc.. ③ Rectal-anal tube diseases: non-specific proctitis, rectal cancer, hemorrhoids, anal fissure, anal fistula, radiation proctitis, rectal polyps, rectal-anal tube injuries. ④ gastrointestinal vascular malformations: such as vascular degeneration and genetic capillary dilatation. 3. Systemic diseases: vitamin C and K deficiency, uremia, epidemic hemorrhagic fever, leukemia, thrombocytopenic purpura, hemophilia, sepsis and so on. If there is any discomfort, it is recommended to go to the hospital as soon as possible, according to the specific conditions, to develop individualized diagnosis and treatment plan.