There are many reasons for dark red blood in the stool: First, dark red blood in the stool indicates that the location of bleeding is far from the anus, which may be a gastrointestinal disease, if the patient has a past history of gastric ulcer, it may be a gastrointestinal ulcer, and gastroscopy can be performed to clarify the diagnosis. Second, if there are small intestinal polyps or small intestinal lesions, small intestinal diverticula, sometimes also lead to dark red blood in the stool, then you can perform small intestinal capsule endoscopy to clarify the diagnosis. Thirdly, if there are colon lesions or appendiceal lesions, they may invade the submucosal vessels and lead to bleeding, which can be diagnosed by colonoscopy. If there is dark red blood in the stool, indicating that the bleeding site is far from the anus, it should be combined with medical history, physical examination and, if necessary, gastroscopy, enteroscopy or small intestine capsule endoscopy to clarify the cause and site of bleeding, and then treat the symptoms.