1. Proctology and Pelvic Floor Clinical Centre, Cisanello University Hospital, Pisa, Italy
2. Proctology and Pelvic Floor Clinical Centre, Cisanello University Hospital, Pisa, Italy and General and Colorectal Surgery, Yarmouk University, Irbid, Jordan
3. Proctology and Pelvic Floor Clinical Centre, Cisanello University Hospital, Pisa, Italy and Cirugia Coloproctologica, Hospital de la Fuerza Aerea de Chile, Santiago de Chile, Chile
4. U.O.C General and Obesity Surgery, University of Study of Campania “Luigi Vanvitelli” Naples, Naples, Italy
5. Department of General Surgery, University of Magna Graecia of Catanzaro - School of Medicine and Surgery, Catanzaro, Italy
6. Section of Statistics, University Hospital of Pisa, Pisa, Italy