Oral sodium phosphate versus sulfate-free polyethylene glycol electrolyte lavage solution in outpatient preparation for colonoscopy: A prospective comparison

Background: Biochemical abnormalities induced by oral sodium phosphate and the risk of cardiac arrhythmias as potential sequelae have yet to be investigated. Methods: We studied 98 outpatients scheduled to undergo diagnostic colonoscopy and prospectively randomized them to receive oral sodium phosphate or sulfate-free polyethylene glycol electrolyte lavage solution (SF-PEG-ELS) as recommended by the manufacturers. Results: Forty-nine patients received sodium phosphate and 49 received SF-PEG-ELS. There was no significant difference in tolerance or quality of preparation as judged by blinded endoscopists. Significant changes in serum sodium, potassium, chloride, calcium, ionized calcium, and inorganic phosphorus levels were noted following sodium phosphate preparation when compared to values before preparation. A significantly greater number of patients who received sodium phosphate preparation had serum potassium and ionized calcium levels that fell into the abnormal range. Ambulatory electrocardiogram monitors placed 24 hours before the preparation and removed after colonescopy showed no increase in ventricular premature contractions or other serious arrhythmias in either group during preparation or colonoscopy. Conclusions: (1) Sodium phosphate and SF-PEG-ELS are equally well tolerated and effective in preparation for outpatient colonoscopy, and (2) sodium phosphate preparation at the recommended dose causes significant alterations in serum sodium, potassium, chloride, calcium, ionized calcium, and phosphorus levels.