EXPERIMENTAL STUDIES OF ENDOSCOPIC MUCOSAL RESECTION FOR COLORECTAL TUMOR

-THE OPTIMUM VOLUME FOR INJECTION AND THE AREA OF RESECTION-

Abstract

Endoscopic mucosal resection (EMR) is a technique used to simplify the resection of sessile colonic polyps. However, there have been no ex vivo studies which confirm the safety of EMR, the location and form of pooling of fluid into the submucosa after injection, the depth of the cutting line or the optimum volume for the injection. We carried out submucosal injection ex vivo and in vivo to investigate these issues. Initially, up to 10 ml saline was gradually injected into the submucosa of ten resected colonic wall samples. Ultrasonography were taken after injecting every 1 ml of saline to determine the height and width of the resulting bleb. In a second study, the resected specimens were frozen in liquid ammonia, cut into tissue blocks and examined under a microscope. In a third study, 29 adenomas were resected by EMR and the relationship between the diameter of each lesion and the thickness of the submucosal layer was measured. As a result, the ratio of height to width reached a maximum at saline volumes of 4-7 ml. Histologically, injected submucosal layer was not separated, but the solution percolated downward through it. A correlation was found between the size of the tumor, the area of resection and the thickness of the submucosa. In conclusion, 1) the optimum volume for the injection was 4-7 ml, and 2) the larger the lesion was resected by EMR, the deeper it was resected.