Effect of four-day psyllium supplementation on bowel preparation for colonoscopy:A prospective double blind randomized trial [ISRCTN76623768]

BACKGROUND: Patients with new onset constipation or presumed hemorrhoid bleeding frequently require the use of both fiber supplements and diagnostic colonoscopy. We sought to determine whether preliminary fiber supplementation would alter the tolerability or efficacy of a standard bowel preparation for colonoscopy METHODS: A prospective, double blind, randomized trial was designed to compare a short course of a psyllium-based supplement versus placebo prior to a colon lavage. Patients were given an unlabeled canister of powder, and instructed to take 1 tablespoon with 8 oz of water bid for 4 days before colonoscopy. A 4-liter polyethylene based glycol lavage was self-administered over 4 hours on the day prior to colonoscopy. A questionnaire on pre-study bowel habits and side effects was completed. Efficacy of the preparation was visually evaluated on a pre-determined scale. RESULTS: There were no significant differences between the two groups in gender, race, age, pre-study stool frequency or consistency. Tolerability was equivalent but efficacy of the bowel preparation was worse in the psyllium group compared to placebo (P < 0.05). CONCLUSIONS: In non-constipated patients psyllium based fiber supplementation should not be initiated in the few days prior to endoscopy using a polyethylene glycol preparation.