The common causes of bleeding in stool during dialysis are hemorrhoid rupture and bleeding, gastrointestinal bleeding, lower gastrointestinal bleeding and so on. 1. Hemorrhoidal rupture and bleeding: many dialysis patients are easy to combine with hemorrhoids, when there is constipation, dry stools and so on, it is easy to lead to hemorrhoidal rupture and bleeding. 2. Upper gastrointestinal bleeding: the urea in the blood of dialysis patients may diffuse to the upper gastrointestinal tract, and the ammonia produced by the decomposition of urea may cause damage to the gastrointestinal mucosa, resulting in erosion, bleeding, ulcers and other symptoms, which may lead to bleeding in the stool. 3. Lower gastrointestinal bleeding: dialysis requires the application of heparin anticoagulation, which can easily lead to platelet dysfunction, causing bleeding in the lower gastrointestinal tract such as colon and rectum, which can eventually be manifested as bleeding in the stool. When bleeding in stool during dialysis, it is recommended to receive relevant examinations in time to clarify the specific causes and carry out timely treatment under the guidance of doctors.