Diarrhea and blood in excretion may be caused by ulcerative colitis, bacillary dysentery, intestinal polyps, colorectal cancer and other diseases. 1. Ulcerative colitis: it can be caused by genetic, environmental, immune, infection and other factors, followed by abdominal pain, diarrhea, mucus, pus and blood stools and a series of symptoms, the longer the course of the disease can also be lethargy, anemia and other symptoms. 2. Bacterial dysentery: because dysentery bacillus infection of the gastrointestinal tract caused by an infectious disease, patients may appear mucus pus and blood stools, diarrhea, abdominal pain, acute and post-traumatic stress (lower abdomen is uncomfortable, very much want to relieve the stools, defecation after a sense of incompletion) and other symptoms. 3. Intestinal polyps: some patients may have changes in bowel habits, such as increased bowel movements, mucous blood stools and other symptoms, accompanied by abdominal distension, abdominal pain and other symptoms. 4. Colorectal cancer: it is a kind of malignant tumor of intestinal tract, which can cause blood in stool, and also changes of stool character and bowel habit, such as diarrhea or constipation. If you have diarrhea and excrement with blood, it is recommended to go to the hospital for consultation, and ask the doctor to make judgment with the specific situation to clarify the cause of the disease.