The Impact of Split-dosed Bowel Preparation on Polyp Detection Rate in the Right Colon: Results of a Randomized Controlled Study

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Purpose: Split-dosed bowel preparation has been shown to improve cleansing efficacy compared to single-dosed bowel preparation. Little data exists evaluating the effect of split-dosing on polyp detection versus single-dosing. The miss rate for right sided colon polyps appears higher than that for left sided polyps and inadequate bowel preparation of the right colon may in part be responsible for this. The aim of this study is to compare bowel cleansing efficacy and polyp detection rates in the right colon between split-dosed versus single-dosed bowel preparation regimens using Miralax/Gatorade and Golytely. Methods: Subjects were randomized into 4 groups: 4L Golytely single-dosed, 4L Golytely split-dosed, 238g Miralax in 64 Oz of Gatorade single-dosed, and Miralax/Gatorade split dosed. Colonoscopies were recorded using video recording software and de-identified. Colonoscopy videos were evaluated for efficacy of cleansing by 2 blinded endoscopists. Two validated bowel preparation scales were used to assess bowel cleansing: the Boston Bowel Prep Scale (BBPS) (0-9 best) and the Ottawa Scale. Data on polyp number and histology was collected for each subject. Results: Data from 221 patients were analyzed (86.2% male, mean age 59.2). 72.4% of split-dosed bowel preparations achieved a BBPS of 8 or 9 compared to 27.5% of the single dosed bowel preparations (p < 0.05). The number of polyps detected per patient was significantly higher with a BBPS of 8 or 9 compared to BBPS of 7 or lower (2.51 vs 1.64 p = 0.05). The number of polyps and adenomas detected per patient in the right colon (proximal to splenic flexure) was significantly higher with a BBPS of 8 or 9 compared to BBPS of 7 or lower (polyps 1.07 vs 0.75, adenomas 0.89 vs 0.62, p < 0.05). Conclusion: Split dosing of either Miralax and Gatorade or Golytely achieved a BBPS of 8 or 9 in significantly more patients than the same regimen singledosed. The number of polyps detected per patient for the whole colon and in the right colon was significantly higher in patients achieving a BBPS of 8 or 9. Split-dosing likely results in increased polyp detection in the right colon compared to single-dosing. This may have implications for improved early detection of colorectal neoplasia using colonoscopy.