To summarize and analyze the etiology of cryptogenic gastrointestinal bleeding and to explore the diagnostic value of different examination methods. Methods The clinical data of 39 cases of surgically treated gastrointestinal hemorrhage from 1992 to 2004 were retrospectively analyzed. Results All 39 patients had pathological diagnosis, all lesions were mainly benign 58.97% (23/39), lesion sites were mostly in the small intestine 89.74% (35/39) compared with the pathological findings, the diagnostic compliance rate of selective arteriography was 56% (14/25), the diagnostic compliance rate of nuclear scan localization was 38.53% (13/34), the diagnostic compliance rate of small intestine intubation segmental air-barium angiography The compliance rate was 22.58% (7/31), and the intraoperative endoscopic diagnosis compliance rate was 85.71% (6/7). Conclusion Most of the lesions of difficult gastrointestinal hemorrhage are in the small intestine, and benign lesions predominate, and preoperative selective arteriography has a high qualitative and localization diagnostic value. Cryptogenic GI bleeding is a more difficult disease to diagnose in GI bleeding. Cryptogenic GI bleeding refers to GI bleeding in which the patient has obvious vomiting and/or blood in the stool, or positive fecal occult blood, and after excluding coagulation disorders and bleeding disorders outside the GI tract, the site and nature of the bleeding cannot be clarified by conventional gastrointestinal endoscopy, X-ray plain film, barium angiography and ultrasound examination. The literature reports that cryptogenic gastrointestinal bleeding accounts for 5%-10% of GI bleeding. In this paper, we summarize and analyze the etiology and diagnosis of 39 patients with cryptogenic gastrointestinal bleeding who were admitted with complete information confirmed by surgery. From January 1992 to November 2004, 39 patients with cryptogenic gastrointestinal hemorrhage were admitted with complete data confirmed by surgery, 28 were male and 11 were female, with a median age of 58 years. 11 patients were in combined hemorrhagic shock, with blood loss of more than 1000 ml, hematocrit decreased to less than 20%, and hematocrit was less than 60 g/L. Gastrointestinal bleeding time was 2d-6m. All patients had preoperative gastroscopy and ultrasound examination. I. Methods and results Preoperative gastrointestinal endoscopy, X-ray plain film, barium contrast (GI) and ultrasound did not reveal any bleeding lesions in 39 patients, and the final surgical and pathological diagnosis was clear. All lesions were predominantly benign 58.97% (23/39), and the lesion sites were mostly in the small intestine 89.74% (35/39) compared with the pathological findings, with a diagnostic compliance rate of 22.58% (7/31) for small intestine intubation segmental gas-barium angiography, 56% (14/25) for selective arteriography, 38.53% (13/34) for nuclear scan localization The intraoperative endoscopic diagnostic compliance rate was 85.71% (6/7). The etiology of cryptogenic gastrointestinal bleeding is complex, and accurate localization of the bleeding location is the key to successful treatment. However, such cases often cannot be detected by current conventional gastrointestinal endoscopy, X-ray plain film, barium angiography and ultrasound examination of the bleeding lesion, increasing the difficulty of clinical etiology and diagnostic analysis. The literature reports that the lesion site of cryptogenic gastrointestinal bleeding is most common in the small intestine [1]. Our data show that the small intestine is the most frequent site, accounting for 89.74%, followed by the duodenum, accounting for 5.13%, and the fundus cardia and colon, each accounting for 2.56%. Gastroduodenal and colonic lesions are often missed due to the small size of the lesion and the influence of intraluminal blood stains, and routine gastroduodenoscopy often fails to reach the ascending duodenum and misses the lesion in this area. According to the nature of the lesion, the literature reports that vascular disease is the most common cause of OGB, and only a few domestic literature reports that it accounts for 20%, and most literature reports that it accounts for 2%, which may be related to the low number of special examinations such as arteriography and small bowel microscopy. In our data, there were 10 cases of vascular disease, accounting for 25.64%, with the majority of sites in the small intestine, which are benign lesions. The bleeding of vascular lesions in this group was clearly diagnosed by selective arteriography in all cases. The most common cause of OGB in China is small intestinal mesenchymal tumor (the previous literature has various diagnoses such as smooth muscle tumor, but now it is unified as mesenchymal tumor), and intestinal bleeding occurs due to mucosal erosion and ulceration of the tumor. In our case, 9 of 11 mesenchymal tumors were clearly diagnosed by selective arteriography. 4 cases of Meckel’s diverticulum and 1 case of duodenal ascending diverticulum were clearly diagnosed by nuclear scan. The previous literature characterized some of the smooth muscle tumors (now unified as mesenchymal tumors) as benign lesions, but now they are more likely to be of low grade malignancy, but benign lesions were still predominant in 58.97% (23/39) of the cases in this group. The site of OGB lesions was mostly in the small intestine, accounting for 89.74% (35/39) of the cases in this group. The lack of effective examination means for small bowel bleeding is not comparable to gastroscopy for diagnosing lesions in the esophagus, stomach and duodenal bulb, and enteroscopy for rectal and colonic lesions. In some cases, because of the critical condition, often combined with shock does not allow moving examination, increasing the difficulty of disease diagnosis. 21.1%-74.4% of the diagnostic compliance rate of X-ray barium meal imaging [2], small intestine intubation segmental gas-barium imaging can increase the positive diagnostic rate of small intestine bleeding by 73.6%; the diagnostic compliance rate of small intestine intubation segmental gas-barium imaging in our data is 22.58% (7 /The preoperative confirmation rate of superior mesenteric artery angiography (DSA) can reach 42%-75% [3]. Due to the rich vascularity of malignant tumors, superior mesenteric arteriography (DSA) is more likely to detect abnormal vessels; the diagnostic compliance rate of selective arteriography in this group was 56% (14/25), which is consistent with the literature; the diagnostic compliance rate of nuclear scan localization was 38.53% (13/34), and small intestinal microscopy is the most ideal examination, and the results of a prospective controlled study suggest that the diagnostic rate of capsule endoscopy for chronic gastrointestinal bleeding was 66% (7/31). The diagnostic rate of capsule endoscopy for chronic gastrointestinal bleeding is 66% [4], but it has not yet been promoted in China, and the operating technique and experience need to be accumulated; the diagnostic rate of intraoperative endoscopy in lower gastrointestinal bleeding is reported to be 88.9% [5], and intraoperative endoscopy has a high diagnostic value when OGB combined with gastrointestinal hemorrhagic shock does not allow further examination and decisive dissection is performed. 85.71% (6/7).