Dividing bowel preparation solution into two doses resulted in better overall quality of the preparation, better polyp and adenoma detection rates, and better colonoscopy completion rates than seen with single-dose administration, in which large volumes of solution must be ingested over the course of a short time. 

Recent studies using split-dose preparations (SDPs) for bowel cleansing in advance of colonoscopy suggest a significant improvement in quality of preparation and in patient compliance. However, to the knowledge of a research team led by Suryakanth R. Gurudu, MD, of the Division of Gastroenterology and Hepatology at Mayo Clinic Arizona, Scottsdale, the effects of SDP on other quality indicators of colonoscopy had not previously been reported.

Gurudu and colleagues sought more information by conducting a retrospective study involving 4,975 persons undergoing screening colonoscopy at a tertiary-care medical center before (3,560 patients) or after (1,615 patients) the implementation of SDP. The bowel preparation choices for split-dosing were 4-liter polyethylene glycol (PEG) electrolyte solution (patients were instructed to drink 3 liters the night before the colonoscopy and the final liter on the day of the procedure, at least 4 hours before the scheduled procedure time) or MoviPrep solution (Salix Pharmaceuticals, Inc., Raleigh, North Carolina; patients were instructed to prepare the solution as per the manufacturer’s directions and drink half of it the night before the procedure and the other half on the day of the test, at least 4 hours before the scheduled colonoscopy time). All patients also were instructed to avoid eating a high-fiber diet for 2 days before taking the bowel preparation, to drink only clear liquids for the entire day before colonoscopy, and to take nothing by mouth for at least 3 hours before the test.

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SDP use increased significantly, from 9% to 74%, after implementation. Compared with the pre-SDP group, both polyp detection rates and adenoma detection rates significantly improved in the post-SDP group (44.1% to 49.5% and 26.7% to 31.8%, respectively). Bowel preparation quality improved significantly in the post-SDP group as well, as did the colonoscopy completion rate (from 93.6% to 95.5% in the post-SDP group).

The researchers did note in their report for Gastrointestinal Endoscopy (2012;76[3]:603-608.e1) that the study was limited by its retrospective design and by the fact that not all the same endoscopists were used in both periods. Nevertheless, they concluded that systemwide implementation of an SDP as the primary choice for colonoscopy significantly improved overall quality of the preparation, polyp and adenoma detection rates, and colonoscopy completion rates.