 The primary endpoint of the study will be to compare the accuracy of two procedures FICE with target biopsies only, versus conventional white light colonoscopy with recommended targeted and random biopsies in the endoscopic surveillance of patient with long-standing UC. Accuracy will be measured based on the number of patients with confirmed neoplasia using each technique. The combined histological outcome following the two procedures will represent the gold-standard diagnosis for each patient. Secondary outcomes will be the number of patients with false-positive findings, the number of neoplastic lesions detected, the number of false-positive lesions per patient for each technique and the total time required for each procedure. 