A low-residue diet before colonoscopy tends to improve tolerability by patients with no differences in preparation quality: a randomized trial.

Background: The pre-colonoscopy diet traditionally involves 24 h of a clear liquid diet (CLD) in combination with a lavage solution; however, this preparation is poorly tolerated.

Aim: To compare the impact on the quality of bowel cleansing and tolerability of a CLD versus a low-residue diet (LRD).

Methods: We performed a randomized trial. Subjects were randomized to CLD or LRD the day before of elective colonoscopy. All subjects received a 4-L preparation of single-dose PEG beginning 16 h prior to colonoscopy. The Boston bowel preparation scale was used to evaluate bowel cleansing; an adequate-quality preparation was defined as a score ≥ 2 per segment.

Results: A total of 205 subjects were included with a mean age (SD) of 55.6 (12.6) years; 133 (64.9%) of them were female. A total of 105 subjects were randomized to receive CLD and 100 to LRD. No significant differences in bowel preparation quality were observed between groups according to the section of colon: right colon (70% vs. 73%, p = 0.08), transverse colon (82% vs. 79%, p = 0.062), or left colon (80% vs. 78.7%, p = 0.28). There was a tendency toward less-frequent nausea (p = 0.08) and vomiting (p = 0.07) in patients with LRD. No differences between groups regarding ADR (12% vs. 10%) were noted.

Conclusions: An LRD before colonoscopy resulted in a tendency toward improved tolerability by patients, with no differences in the quality of bowel preparation.