[1] Epsom & St Helier Univ Hosp NHS Trust, Carshalton SM5 1AA, England
[2] Gateshead Hlth NHS Fdn Trust, Gateshead NE9 6SX, England
[3] Portsmouth Hosp Univ NHS Trust, Queen Alexandra Hosp, Victory Inst Minimal Access Surg, Dept Colorectal Surg, Portsmouth PO6 3LY, England
[4] Univ Roma, Tor Vergata Hosp, Dept Surg, Minimally Invas Unit, Viale Oxford 81, I-00133 Rome, Italy