Endoscopic submucosal dissection for large superficial colorectal tumors using the "clip-flap method".

Background And Study Aims: Endoscopic submucosal dissection (ESD) is technically difficult because of poor visualization and instability in the cutting area. Although mucosal flap formation improves visualization of the cutting area, it is difficult to achieve, especially in colorectal ESD. To facilitate mucosal flap formation, we developed the "clip-flap method" by substituting an endoclip for the mucosal flap until it is formed.