Submucosal endoscopy with mucosal flap safety valve (SEMF) technique: a safe access method into the peritoneal cavity and mediastinum.

Natural orifice translumenal endoscopic surgery (NOTES) is a unique emerging surgical concept expanding flexible endoscopy beyond the gut wall. The methods and technology growing from this concept may minimize trauma from surgical access to the peritoneal cavity by completely eliminating body surface incisions. Our colleagues at the Mayo Clinic have explored, over several years, the concept of using the submucosa as a working space for endoscopic interventions, such as resection of mucosal neoplasias and submucosal tumors, as well as for the acquisition of muscular tissue for etiologic analysis of motility disorders. The submucosal space can also be utilized as a protective tunnel preventing peritoneal soiling by using the free overlying mucosa, as a sealant flap, and permitting a safer offset entry into the peritoneal and thoracic cavities for NOTES. In the SEMF technique, the submucosal space is mechanically created by balloon dissection facilitated by either high-pressure CO2 gas injection or chemically 'softening' the submucosal connective tissues. This article reviews and describes SEMF in detail along with applications involving in vivo porcine models.