1. Endoscopy Unit, Azienda Ospedaliero Universitaria Pisana, 56125 Pisa, Italy
2. Gastroenterology Unit, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56100 Pisa, Italy
3. Digestive Disease Centre, Division of Surgery, Barking, Havering and Redbridge University Hospitals NHS Trust, Romford RM70AG, UK