Half at Night and Half in the Morning—a Better Way To Prepare for Colonoscopies

Gastroenterologists and other physicians are virtually unanimous in appreciating the vital importance of colonoscopy screenings. In preparation for colonoscopies, we direct patients to drink a large volume of bowel-cleansing liquid, usually in one day. Past studies have shown that splitting this dose—drinking half the night before and half in the morning before the procedure—leads to better bowel cleansing compared with drinking the entire dose the night before. Yet barriers still remain to the acceptance of split dosing, including the perceived patient inconvenience of consuming two separate doses. My colleagues and I wanted to learn whether the split-dose preparation is more convenient for patients, and whether it would lead to finding more precancerous polyps. Split dosing is already recommended by the U.S. Multi-Society Task-Force on Colorectal Cancer, and our study provides additional support for its benefits by demonstrating that it decreases total bowel prep ingestion time, reduces the intensity and duration of bowel movements, and is associated with less sleep disruption. The results were clear to us in confirming the superior performance of the split dose, not only in overall bowel cleansing, but in detecting dangerous polyps. Our team, including Carol Burke, MD, found that endoscopists reported “excellent” or “good” cleansing in 95.6% of the split-dose group, a full 10 percentage points above the single-dose group, which achieved those ratings in only 85.5% of cases. The split-dose method also resulted in a higher overall rate of finding polyps and adenomas. However, the most dramatic difference was specifically seen in detecting another serious and potentially life-threatening condition—the presence of sessile serrated polyps (SSPs). In screening patients from both groups, the physicians found SSPs at a rate four times higher in the split-dose group than in the single-dose group (9.9% vs. 2.4%). We regard our results as additional evidence for practitioners to confidently adopt split dosing as a standard procedure. For patients who aren’t given this option, we recommend they ask their GI about it. The improved ability to detect SSPs is too significant a benefit to overlook in our continuing effort to eliminate colorectal cancer. Nicholas Horton, MD, is a PGY-2 resident in internal medicine at the Cleveland Clinic. He completed medical school at the Wright State University Boonshoft School of Medicine, in Dayton, Ohio. He plans to pursue a fellowship in gastroenterology, and has a particular academic interest in colorectal cancer prevention and inflammatory bowel disease. Dr. Horton presented data from this study, “Sessile Serrated Polyps Are Detected More Often With Split Versus Single Dose Low Volume Bowel Preparation: Results From a Prospective Trial,” at the 2016 Digestive Disease Week (abstract Su1663). The study received outside funding from Salix Pharmaceuticals.