The discharge of black stool with blood may be dietary, drug related, or may be digestive system diseases, blood system diseases and other causes of gastrointestinal bleeding. 1. Food and drug related:Consumption of large amounts of black sesame, mulberry and other black foods can lead to black stools; consumption of bismuth, iron and other drugs can also make stools black. 2. Digestive system diseases: peptic ulcer, cirrhosis, rupture and bleeding of esophagogastric varices, gastric cancer and other upper gastrointestinal bleeding, hemoglobin in the intestinal tract to react, resulting in black stools; colorectal cancer, intestinal polyps, ulcerative colitis, hemorrhoids, and other lower gastrointestinal bleeding, the blood in the intestinal tract stays for a short period of time, resulting in red blood stools. 3. Blood system diseases: hemophilia, leukemia, myelodysplastic syndrome, thrombocytopenic purpura, allergic purpura, coagulation anomalies and other diseases can easily lead to gastrointestinal bleeding, resulting in black stools or blood in the stool. The discharge of black stool with blood should be promptly to the hospital, under the guidance of the doctor treatment.