Polyethylene glycol versus sodium phosphate in bowel cleansing for colonoscopy: a randomized trial

There have been conflicting results regarding the adverse effects of established bowel cleansing regimens. The aim of the present study was to compare the effects of three bowel cleansing regimens on subjective well-being, electrolyte balance, cardiac arrhythmia, and the microscopic post-cleansing appearance of the colonic mucosa.

A total of 231 consecutive outpatients were randomly assigned to receive bowel preparation for colonoscopy with either 4 l polyethylene glycol (PEG; group I, n = 76); 2 l PEG plus 10 mg Bisacodyl (group II, n = 71); or 90 ml sodium phosphate (group III, n = 84). After bowel preparation, the participants completed a questionnaire on symptoms. Endoscopists blinded to the regimen used gave scores for the quality of cleansing at endoscopy, ranging from poor (0) to very good (5). Blood samples were taken before and after bowel cleansing, electrocardiographic monitoring was used during colonoscopy, and mucosal biopsy samples were taken in the sigmoid colon.

Bowel preparation in group II was poorer (mean score 3.26) than in groups I (3.88) and III (4.01); P < 0.001 (II vs. III), P < 0.001 (I vs. II). The frequency of arrhythmias and post-cleansing mucosal inflammation was similar in all three groups. Lower serum potassium and higher serum phosphate concentrations were found in group III in comparison with the other groups ( P < 0.001).

No differences were detected regarding the effectiveness and safety of bowel preparation with PEG alone and sodium phosphate in individuals without cardiac, renal, or hepatic failure, despite a significantly stronger alteration of the electrolyte balance with sodium phosphate.