The causes of frequent blood in stool are as follows: First, rectal and perianal lesions: may be caused by some lesions in the rectum and perianal area, which can be benign lesions, such as hemorrhoids, anal fissures, proctitis, etc., or malignant tumors in the rectum and perianal area, such as anal canal cancer, rectal cancer, etc. Second, upper gastrointestinal tract diseases: If it is black stool, it may also be caused by bleeding diseases in the upper gastrointestinal tract, such as gastritis, gastric ulcer, gastric cancer, etc. Generally, the amount of bleeding is relatively small and after mixing with gastric juice, the blood becomes black. If you have frequent blood in the stool, it is recommended to go to a regular specialized hospital for systematic examination in a timely manner. First of all, the site of bleeding should be roughly defined. If it is upper gastrointestinal tract, gastroscopy is generally recommended to make a clear diagnosis. If lower gastrointestinal bleeding is suspected, colonoscopy is generally recommended to make a clear diagnosis and then take corresponding treatment measures according to different etiologies for timely treatment.