Bleeding from the small intestine occurs when the feces are mainly thin and thick, with blood in the feces, and some people have black feces. The main role of the small intestine is to absorb the nutrients in food, once bleeding occurs in the small intestine, the function of the small intestine will be impaired, unable to absorb the nutrients in the food, the food will be discharged into the large intestine as it is and excreted through the peristaltic movement of the large intestine, the nature of the feces is relatively dilute and thick, and some people will be accompanied by a foamy form. When the peristalsis of the intestines is too rapid, the blood is not oxidized and therefore some blood is carried in the stool. A small proportion of patients with small bowel bleeding have relatively slow stool expulsion, the blood is retained in the intestinal system for a relatively long time, so it will be oxidized by the intestinal fluid secreted by the intestinal tract, and the stools of these people are mainly tarry stools. Some of the small intestinal bleeding is mainly occult bleeding, the amount of bleeding is relatively small, the shape of the stool is relatively normal, but when the patient is examined in the stool, a positive occult blood test can be found.