Preparation before colonoscopy: a randomized controlled trial comparing different regimes.

A good bowel preparation is essential for optimal visualization of the large intestine. Several preparations with a difference in composition and volume are available. We compared five methods for bowel cleansing quality and patients' acceptability. Adult ambulatory outpatients scheduled for elective colonoscopy were randomized to receive 4-l polyethylene glycol (PEG) solution (Klean-prep), 2-l PEG solution+ascorbic acid (Moviprep), or a sodium phosphate (NaP) solution, Phosphoral. Patients with the PEG solutions were also randomized to receive simethicone (Aeropax), to investigate whether this improves the bowel cleansing efficacy. Before colonoscopy patients completed a questionnaire about the acceptability and tolerability of the preparation. Endoscopists blinded to the type of preparation gave a bowel cleansing score. Data were available for 461 patients. 2-l PEG+ascorbic acid was noninferior to 4-l PEG in bowel cleansing quality of rectosigmoid and colon. NaP was noninferior to 4-l PEG in bowel cleansing quality of rectosigmoid but inferior for the whole colon. Compliance was significantly less in the group with 4-l PEG compared with the 2-l PEG and NaP group. No difference was found for abdominal cramps. Taste was significantly better in the 2-l PEG group. Simethicone did not improve the bowel cleansing quality. 2-l PEG+ascorbic acid was noninferior to the 4-l PEG solution in bowel cleansing quality and was better in taste and compliance. NaP was inferior to 4-l PEG in bowel cleansing quality. Addition of simethicone gave no improvement.