Submucosal Endoscopy - A Novel Approach to En Bloc Endoscopic Mucosal Resection

Abstract

Background: The submucosal layer is of eminent importance for polypectomy and endoscopic mucosal resection in the gastrointestinal tract. Submucosal infiltration is the critical step of tumor invasion and subsequent metastasis. A mucosal neoplastic lesion has to be stripped off the underlying muscular layer during an endoscopic resection. Herein we describe for the first time the development of submucosal endoscopy (SE), a novel and innovative method, that allows diagnostic and therapeutic endoscopy of the submucosal space (SS) in the esophagus (E). Materials and Methods: SE was performed in pigs under general anesthesia. After placing a plastic tube in the proximal E for a quick access a right-angled area was marked with a diathermic probe to define a mucosal piece for resection. After local infiltration of the submucosa with epinephrine (1:100000) a 1-2 cm transverse incision was performed with a Storz normal calibre videoendoscope (NCVE) 2-3 cm proximal and distal of these margins. Through the proximal incision we entered the SS with a flexible Storz small calibre videoendoskop and dissected the net-shaped submucosal connective tissue in a longitudinal direction with a blunt forceps. Coarse fibres and blood vessels were coagulated and severed. The lifted mucosa was subsequently separated with the NCVE and an insulated-tip needle-knife. The resected particle was retrieved with a snare. Finally the animals were euthanized and the explanted E was tested for leakages by inspection and hard filling with water. Results: Overall 15 mucosal pieces were resected. The size of the resected pieces varied from 1,6 cm × 0,9 cm to 7,4 cm × 1,7 cm. All of them could be completely resected en bloc. The mean time for resection of one mucosal piece was 36 min (median time 25 min, range 16-108 min). The endoscopic view in the SS was excellent. The blunt and diathermic dissection of the submucosal connective tissue was unproblematic. In the SS inspection of the muscularis and of the underside of the mucosa was easily accomplishable. There were no bleeding and no perforation of the muscularis. Conclusions: Diving into the SS for SE is a novel, innovative and practicable method for the dissection of mucosal neoplastic lesions. We demonstrate, that mucosal areas of various sizes could be resected en bloc without complications. The sight in the SS was surprisingly good. We speculate that the penetration of a tumor into the SS would accurately be assessed by SE. Lesions limited to the mucosa would get resected en bloc according to oncologic standards by this novel method. Human trials will show whether peritumorous inflammatory changes may impede submucosal dissection.