Low incidence of deep vein thrombosis after double-balloon endoscopy and colorectal submucosal dissection: Multicenter, prospective study - Tomoya Sugiyama; Takahito Katano; Takaya Shimura; Masahide Ebi; Takanori Ozeki; Takashi Mizushima; Yoshikazu Hirata; Keisuke Ito; Keiji Ozeki; Yoshiharu Yamaguchi; Ryo Ishihara; Kazuhiro Yamamoto; et al. (Endoscopy International Open)