Procedure

All patients enrolled received the same split-dose low-volume bowel preparation (2 L polyethylene glycol + simethicone + electrolytes).

All endoscopic examinations were performed by the same experienced endoscopist with the same model of colonoscope, using a combination of intravenous midazolam and fentanyl at a starting dose of 3 mg and 50 µg, respectively.

We used specifically designed questionnaires to collect data on the tolerability of the bowel preparation and endoscopic procedure; they were administered by a blinded endoscopy nurse. Within 1 hour before the procedure, subjects were asked to fill in a questionnaire to evaluate bowel preparation tolerability; immediately after the procedure, when woken up, they were asked to complete the questionnaire to assess the tolerability of the endoscopic procedure. Bowel preparation tolerability, abdominal pain, and discomfort experienced during colonoscopy, and overall endoscopic procedure tolerability was measured using a Visual Analogue Scale (VAS) from 0 to 100 mm. VAS was recorded by the same endoscopy nurse trained by a single education module, to provide objective, consistent evaluation across all CD/UC/SS subjects.

For each colonoscopy, we recorded indication, examination completion (defined as terminal ileum intubation), disease activity, using a Mayo endoscopic score for UC¹⁶ and Simple Endoscopic Score for Crohn’s Disease (SES-CD) for CD,¹⁸ adjustment to sedation dose, and the amount of additional midazolam and fentanyl. Quality of bowel preparation was assessed by Boston Bowel Preparation Scale (BBPS)¹⁹: adequate if BBPS BP6, with a minimum of 2 for each segment. Well-tolerated bowel preparation and endoscopic procedure were defined by a VAS > 70 mm.