Methods: In this study the investigators propose to use an endoscopic technique that eliminates the need for open or laparoscopic surgery and provides a more robust endoscopic repair than is possible with traditional endoscopic tools. Patients who are scheduled to undergo surgery for intestinal fistulas will be screened for study eligibility. Patients who are scheduled to undergo complex polypectomy, or submucosal dissection will be screened for study eligibility and informed about all possible therapies in case of an iatrogenic perforation (open - laparoscopic surgery, endoscopic clipping, endoscopic closure with tissue anchors). A commercially available flexible endoscope will be inserted through the mouth and the fistula or perforation will be closed using the Tissue Approximation System (Ethicon Endo Surgery, Cincinnati, OH).