Abstract:Abstract: Objective?To evaluate the effects and safety of underwater endoscopic resection for gastrointestinal tumors.?Methods?After searching the PubMed, a search engine of the National Library of Medicine, Underwater endoscopic mucosal resection, Underwater endoscopic submucosal dissection and Underwater peroral endoscopic myotomy, respectively, relevant documents were retrieved and the cases were summarized.?Results?40 related articles were retrieved and enrolled in 452 cases, including 413 cases of underwater endoscopic mucosal resection (UEMR), 37 cases of underwater endoscopic submucosal dissection (UESD), underwater peroral endoscopic myotomy (UPOEM) in 2 cases. There were 468 lesions in 413 UEMR patients, with a successful resection rate of 98.5%. The en bloc resection rate was 61.1%, and the R0 resection rate was 94.3% in the en bloc resection; There were 39 lesions in 37 UESD patients and all the lesions were completely dissection by UESD; 2 cases of UPOEM were performed to create a tunnel and underwater myotomy successfully. Postoperative complications included bleeding, perforation, duodenal stricture formation, hyponatremia, aspiration pneumonia and postpolypectomy syndrome.?Conclusion?Underwater endoscopic resection appears to be an easy, safe and effective technique. In the future, more clinical studies and long-term follow-up data are needed to clarify the advantages and indications of underwater endoscopic resection compared with conventional EMR or ESD.