Fecal bleeding, including black stools and fresh blood, is the most common clinical manifestation of GI bleeding and often hides a variety of diseases behind it. The clinical manifestations of GI bleeding depend on the site of bleeding, the amount of bleeding and the speed of bleeding. Generally speaking, black stools mostly come from the upper GI tract, while bright red blood stools mostly come from the lower GI tract, but not absolutely. Common causes of upper gastrointestinal bleeding: 1. peptic ulcer (mainly including gastric ulcer and duodenal ulcer); 2. rupture and bleeding of esophagogastric fundic varices in cirrhosis; 3. acute gastric mucosal lesions; 4. upper gastrointestinal tumor (mainly gastric cancer and esophageal cancer). Common causes of lower gastrointestinal bleeding: 1. anorectal inflammatory lesions: including hemorrhoids, anal fissures, anorectal inflammation, etc.; 2. lower gastrointestinal tumors: mainly seen in colorectal cancer, colorectal polyps, etc.; 3. vascular lesions: ischemic enteritis, mesenteric thrombosis or embolism, etc., mainly seen in the elderly; 4. certain acute infectious diseases, intestinal parasitic diseases, blood and hematopoietic system diseases, etc. How to standardize the diagnosis and treatment of fecal bleeding? Patients often come to the gastroenterology clinic with bleeding stools, but because they lack professional knowledge, or they know some medical knowledge, or they have friends with similar clinical manifestations, they think it is caused by hemorrhoids and do not pay attention to it. Although clinically, especially in male patients, blood in the stool is often caused by hemorrhoids, it is also found that quite a few patients initially thought it was hemorrhoids and further colonoscopy resulted in colorectal cancer, delaying the best time for treatment. In addition to detailed medical history and comprehensive physical examination, relevant specialized laboratory and auxiliary examinations should be performed: 1. routine stool + occult blood examination; 2. serum tumor marker examination; 3. gastroscopy; 4. imaging examination: including ultrasound, X-ray imaging, CT, MRI, angiography, etc. Of course, not every patient must check all the above items, but for the confirmation of diagnosis of bleeding caused by gastrointestinal tumor, gastroscopy is necessary.