Underwater Resection of Colorectal Neoplasia: Taking the Plunge Into a New Technique

Abstract

FigureIntroduction: The optimal method for safe and effective endoscopic resection of benign colorectal neoplasia is dictated by lesion size, location and configuration, with the ideal goal of en bloc resection to reduce the risk of local neoplastic recurrence. Resection of colorectal lesions is traditionally performed with the colon fully distended with gas. Submucosal injection of fluid is also often utilized for larger lesions to assist with safe resection. Methods: An emerging approach to polypectomy involves gas exclusion in a partially distended, water filled lumen, without the use of submucosal injection.Observed and theoretical advantages to this technique can be broadly divided into 4 categories: 1) Enhanced visualization and detection: - Water creates a natural magnification affect, enhancing detection of lesions and allowing detailed examination of vasculature, pit patterns and mucosal irregularities. - The buoyancy of mucosal lesions in a fluid filled lumen suspends polyps, even flat ones, above the surrounding tissue. 2) Separation of mucosa and muscularis propria (MP) - The MP retains its circular shape even when the lumen is collapsed, creating natural separation between the mucosa and deeper muscle layer. - The need for submucosal injection prior to mucosal resection is eliminated as the chance for muscle injury is decreased with the natural separation of layers. - Wall tension is reduced in a collapsed lumen, allowing the MP to retain its full thickness, further decreasing the chance of perforation. 3) Alterations in polyp size, morphology and configuration - The mucosal surface area in a distended or collapsed colon remains constant, so the mucosa must involute and invaginate in a non-distened lumen, altering the normal mucosal topography and reducing the footprint of mucosally based lesions, increasing the success of en bloc resection. 4) Reduced resource utilization - Fewer endoscopic accessories used with elimination of submucosal injection. - Less frequent endoscopic follow up exams with higher en bloc resection rates. - Decreased need to refer difficult or large polyps to other providers. Results: We present 4 examples of underwater resection of colorectal lesions. Conclusion: Underwater resection of colorectal lesions is a novel approach. It has potential advantages that may assist with safer, more efficient, effective and less resource intensive therapy. It is easily learned by endoscopists familiar with conventional techniques and is another tool in the armamentarium for polypectomy.