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Therap Adv Gastroenterol. 2013 Jan;6(1):5-14. doi: 10.1177/1756283X12464100.

Split dose and MiraLAX-based purgatives to enhance bowel preparation quality becoming common recommendations in the US.

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  • 1Associate Research Scientist, Department of Epidemiology, Mailman School of Public Health, Columbia University, 722 West 168th Street, New York, NY 10032, USA.



Rates of suboptimal bowel preparation up to 30% have been reported. Liberalized precolonoscopy diet, split dose purgative, and the use of MiraLAX-based bowel preparation (MBBP) prior to colonoscopy are recently developed measures to improve bowel preparation quality but little is known about the utilization prevalence of these measures. We examined the patterns of utilization of these newer approaches to improve precolonoscopy bowel preparation quality among American gastroenterologists.


Surveys were distributed to a random sample of members of the American College of Gastroenterologists. Participants were queried regarding demographics, practice characteristics, and bowel preparation recommendations including recommendations for liberal dietary restrictions, split dose purgative, and the use of MBBP. Approaches were evaluated individually and in combination.


Of the 999 eligible participants, 288 responded; 15.2% recommended a liberal diet, 60.0% split dose purgative, and 37.4% MBBP. Diet recommendations varied geographically with gastroenterologists in the West more likely to recommend a restrictive diet (odds ratio [OR] 2.98, 95% confidence interval [CI] 1.16-7.67) and physicians in the Northeast more likely to recommend a liberal diet more likely. Older physicians more often recommended split dosing (OR 1.04, 95% CI 1.04-2.97). Use of MBBP was more common in suburban settings (OR 2.14, 95% CI 1.23-3.73). Evidence suggests that physicians in private practice were more likely to prescribe split dosing (p = 0.03) and less often recommended MBBP (p = 0.02). Likelihood of prescribing MBBP increased as weekly volume of colonoscopy increased (p = 0.03).


To enhance bowel preparation quality American gastroenterologists commonly use purgative split dosing. The use of MBBP is becoming more prevalent while a liberalized diet is infrequently recommended. Utilization of these newer approaches to improve bowel preparation quality varies by physician and practice characteristics. Further evaluation of the patterns of usage of these measures is indicated.


MiraLAX; bowel preparation; colonoscopy; liberal diet; split dose purgative

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