The preparation used in the study is a combination of a 2 L sulphate-free iso-osmotic formulation of of PEG-4000 added with citrates and simethicone (PEG-CS) (Lovol-esse; AlfaWassermann, Bologna, Italy. Kit contains 4 pouches, each containing 64.5gr of PEG, to be dissolved in 2 L of water.), and bisacodyl 5 mg tablets (Lovodyl; Alfa-Wassermann, Bologna, Italy).