Prospective, randomized, endoscopic-blinded trial comparing precolonoscopy bowel cleansing methods

Recent reports have suggested that precolonoscopy bowel preparation is easier to tolerate if a small volume solution is used. Therefore, the aim of this study was to compare three oral solutions for colonoscopy to determine any changes in either patient compliance or cleansing ability.

Four hundred fifty patients were prospectively randomized to receive either a standard 4-liter polyethylene glycol solution, a newer sulfate-free 4-liter polyethylene glycol solution, or a 90-ml oral sodium phosphate preparation. Before and after bowel preparation all patients were weighed, and serum electrolytes as well as phosphate, magnesium, calcium, and osmolarity were measured. In addition, a detailed questionnaire was used to assess side effects and patient satisfaction. Endoscopists blinded to the type and quantity of preparation used scored the type of residual stool and the percentage of bowel wall visualized for each segment of colon and for the overall examination. Nurses recorded all procedure times as well as the quantity of irrigation and aspiration.

Four hundred twenty-two age-matched and sex-matched patients completed all phases of the trial. There were no clinically significant changes in weight or in any biochemical parameters. There was, however, asymptomatic hyperphosphatemia in the sodium phosphate group (P < 0.01). The length of time to the cecum was similar for all three groups, with a higher volume of fluid suctioned for sodium phosphate (P < 0.01). Overall, endoscopists scored sodium phosphate as "excellent" or "good" in 90 percent vs. 70 percent and 73 percent after the polyethylene glycol or sulfate-free lavage, respectively (P < 0.01). Particulate or solid stool was found in all segments of the colon more frequently after both large volume preparations than after sodium phosphate (P < 0.05). There were no significant differences in the frequency or intensity of any of the 11 side effects questioned. Eighty-three percent of the patients who received the sodium phosphate preparation stated they would take this same preparation again, vs. only 19 percent and 33 percent for polyethylene glycol and the sulfate-free lavage, respectively (P < 0.01).

The smaller volume oral sodium phosphate was not associated with any clinically significant problem, caused no increase in the incidence of side effects, was preferred by patients, and was more effective in colonic cleansing. However, the hyperphosphatemia seen may limit its use in patients with impaired renal function.