1. Epsom and St. Helier University Hospitals NHS Trust, Carshalton SM5 1AA, UK
2. Gateshead Health NHS Foundation Trust, Gateshead NE9 6SX, UK
3. Department of Colorectal Surgery, Victory Institute of Minimal Access Surgery, Queen Alexandra Hospital, Portsmouth Hospitals University NHS Trust, Portsmouth PO6 3LY, UK
4. Department of Surgery, Minimally Invasive Unit, Università degli Studi di Roma, Tor Vergata Hospital, Viale Oxford 81, 00133 Rome, Italy