What is meant by unexplained gastrointestinal bleeding? It is simply defined as recurrent or persistent gastrointestinal bleeding in which the cause of the bleeding is not identified by conventional endoscopy (gastroscopy and colonoscopy). Some people may wonder why there are still “unexplained” bleeding when today’s medicine is so advanced that it is fully capable of examining people from the inside out. The reality is that there are not only a lot of them (especially in our hospital, where patients are screened from the grassroots level), but they are also a headache, not only for the gastroenterologists but also for the gastrointestinal surgeons. Recently, we have encountered several cases of unexplained gastrointestinal bleeding in the ward, including patients whose hemoglobin dropped to 40g/L and fainted; patients who went into shock from hemorrhage and were transferred to the hospital one day immediately after the operation because the cause of bleeding was not found in the local hospital’s emergency caesarean section + intraoperative colonoscopy; and more patients who had several recurrent episodes of gastrointestinal bleeding over several years, each of which was resuscitated and went through multiple They had gone through gastroscopy, colonoscopy, capsule endoscopy, small intestine microscopy, abdominal vascular intervention, abdominal CT, nuclear imaging, etc., and spent a lot of money and had their intestines cleaned again and again, but still could not make a clear diagnosis. It is true that today’s medicine has advanced, and the small intestine, which was previously inaccessible, can now be accessed through capsule endoscopy and small bowel microscopy, but are patients really benefited? I don’t think so. Small bowel microscopy is a very painful thing, not only for the patient, but also for the doctor. The small intestine, which is about 6 meters long, hovers over the abdomen and is examined in two steps, entering transanally if the lesion is estimated to be near the lower part of the intestine, and entering through the mouth if the lesion is estimated to be superior. Due to technical reasons and factors such as intestinal adhesions, it is difficult to really “meet” the upper and lower parts of the patient. In other words, it is difficult to examine the small intestine thoroughly. During this process, it is difficult for the patient to undergo such a painful examination while awake. Simple intravenous anesthesia can not last for several hours, so we now generally choose general anesthesia by tracheal intubation. The risk of bleeding and perforation during the procedure is much higher than that of colonoscopy, and the time and effort required by the examining physician is no less than that of a surgeon performing a dissection. Even after such a difficult examination, it is still possible to find nothing, or to find some lesions but have difficulty in determining the relationship between the lesions and the gastrointestinal bleeding. What should be done in such cases? Some people say that selective abdominal angiography is the best way to detect the lesion and to immediately embolize the vessel to stop the hemorrhage. However, I have encountered a patient with bleeding who was hospitalized for repeated bleeding, and each time he went to the hospital after massive bleeding, no problem was found. Each time he was discharged from the hospital, the doctor told him that the next bleeding must be sent to the hospital as fast as possible, and that he should try not to use drugs to stop the bleeding, because the bleeding volume should be at least 0.5 ml/min or more during the imaging to detect more accurately the contrast agent spilling from the vessel into the signs of intestinal tract. The patient’s family said that it was hard to describe the desperation of seeing the blood flowing out of the patient’s body during the transportation to the hospital and the whole process of admission and imaging because no hemostatic drugs were used. Even so, no specific bleeding lesion was found during the final angiogram. What should be done then? For painless gastrointestinal bleeding, most of the factors considered to be due to ruptured blood vessels (such as hemangioma, vascular malformation, gastrointestinal diverticulum, etc.), the treatment options of internal medicine are really limited. The best hope is to find the site of bleeding and ask the surgeon to remove it. But nowadays, because surgeons are busy doing surgery for intestinal tumors, they are not sure about the cause of these GI bleeding, and it takes a long time to do the dissection, and the bleeding may continue after the surgery, so the family may complain about the patient who is not treated well, and it is not done if it can be done. Then our gastroenterologists can only see such patients again and again, and arrange various tests again and again, in vain.