Single-day, divided-dose oral sodium phosphate laxative versus intestinal lavage as preparation for colonoscopy: efficacy and patient tolerance.

Polyethylene glycol-electrolyte lavage solutions are widely used to prepare the colon for colonoscopy. Unfortunately, some patients find this preparation difficult to complete. Recent studies of a sodium phosphate-based laxative have shown both good patient tolerance and good bowel preparation. In these studies, the laxative has generally been prescribed in two doses, with the second dose taken early the morning of colonoscopy. Because the morning dose is inconvenient for many patients, we compared giving a common polyethylene glycol-based electrolyte lavage solution the day before colonoscopy with our method of giving both doses of sodium phosphate-based laxative the day before colonoscopy: one dose at 4 PM and the second dose at 8 PM. We judged efficacy by an assessment of residual liquid and fecal matter in the colon and judged tolerance by the results of a symptom questionnaire completed by each patient immediately before the procedure. Our results in more than 200 patients showed similar efficacy ratings and similar symptom scores for both preparations, but patients rated the sodium phosphate-based preparation as easier to tolerate. In conclusion, in selected patients this new dosing method for sodium phosphate is preferable to large-volume, whole-gut lavage solutions.