Bowel preparations administered the morning of colonoscopy provide similar efficacy to a split dose regimen, according to a study conducted by a team of researchers led by Danny Avalos, MD, of Texas Tech University Health Sciences Center, Division Gastroenterology, El Paso, TX.

The researchers conducted a meta-analysis of 15 randomized controlled trials comparing the efficacy of same-day versus split dose bowel preparations for colonoscopy. They found no difference between the categorical outcome for any same-day, high-quality bowel preparation vs. any split preparation (RR 0.95 [0.90;1.00], P=0.62). 

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Results showed that adenoma detection rate (ADR) did not differ between groups (RR 0.97 [0.79;1.20], P=0.81). Additionally willingness to repeat (RR 1.14 [0.96,1.36], P=0.14) and tolerability (RR 1.00 [0.96;1.04], P=0.98) did not differ.

Bloating was less frequent among the same-day preparation group, (RR 0.68 [0.40;0.94, P=0.02). Same-day preparation was also associated with less interference with sleep. Otherwise, adverse events did not differ.

The researchers concluded that there were no “clinically significant differences among recipients of same day or split dose regimens.” They added, “Given lack of clinical differences, patient preference should dictate timing of colonoscopy preparation.”


Avalos DJ, Castro FJ, Zuckerman MJ, et al. Bowel Preparations Administered the Morning of Colonoscopy Provide Similar Efficacy to a Split Dose Regimen: A Meta Analysis. J Clin Gastroenterol. 2017 Sep 6. [Epub ahead of print]