New classification system for radical rectal cancer surgery based on membrane anatomy

Figure 4 The lateral resection lines of type B1 and type B2 surgeries in cadaver dissection. A: The aggregated pelvic plexus can be separated from the urogenital fascia to complete a nerve-sparing type B1 procedure (white dotted line); B: The diffuse pelvic plexus is in tight contact with the urogenital fascia and has to be resected together with the urogenital fascia, which corresponds to the type B2 procedure (yellow dotted line).