An Electrosurgical Endoknife with a Water-Jet Function (Flushknife) Proves Its Merits in Colorectal Endoscopic Submucosal Dissection Especially for the Cases Which Should Be RemovedEn Bloc

Background . Previously, we reported that the Flushknife (electrosurgical endoknife with a water-jet function) could reduce the operation time of colorectal endoscopic submucosal dissection (ESD) however, suitable situation for the Flushknife was obscure. This subgroup analysis of a prospective randomized controlled trial was aimed to investigate the suitable situation for the Flushknife. Methods . A total of 48 superficial colorectal neoplasms that underwent ESD using either the Flexknife or the Flushknife in a referral center were enrolled. The differences of operation time between the Flexknife and the Flushknife groups in each subgroup (tumor size, location, and macroscopic type) were analyzed. Results . Median (95% CI) operation time calculated using survival curves was significantly shorter in the Flushknife group than in the Flexknife group (55.5 min [41, 78] versus 74.0 [57, 90] min; P = 0.039, Hazard Ratio HR: 0.53; 95% CI (0.29–0.97)). In particular, the HR in patients with laterally spreading tumors-nongranular type (LST-NG) in the Flushknife group was significantly smaller than in the Flexknife group (HR: 0.165→0.17; 95% CI (0.04–0.66)). There was a trend of decreasing HRs according to larger lesion size. Conclusions . The Flushknife proved its merits in colorectal ESD especially for the lesions which should be removed en bloc (LST-NG and large lesion).