Pierre Chapuis1, Ming Zhang2, Les Bokey3. 1. Department of Colorectal Surgery, Concord Hospital and the Discipline of Surgery, Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia. 2. Department of Anatomy, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand. 3. Department of Colorectal Surgery, Liverpool Hospital and School of Medicine, Western Sydney University, Sydney, New South Wales, Australia.