1 Proctology Unit, Division of Digestive Surgery, University Hospitals of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211, Genève 14, Switzerland.
2 Clinique de Grangettes, 7 chemin des Grangettes, 1224, Chêne-Bougeries, Switzerland.
3 Proctology Unit, Division of Digestive Surgery, University Hospitals of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211, Genève 14, Switzerland. Frederic.ris@hcuge.ch.