Low-volume bowel prep appears as effective as high-volume for colonoscopy

No significant between-group differences were seen for low-volume versus high-volume split-dose regimens in adequacy of bowel cleansing, while low-volume regimens had higher odds of patient adherence or completion, tolerability, and willingness to repeat.


Low-volume split-dose bowel preparation regimens may be as effective as high-volume split-dose regimens before colonoscopy, according to a recent study.

Researchers performed a systematic review and meta-analysis of randomized controlled trials published through Jan. 31, 2019, that compared low-volume polyethylene glycol (PEG) and non-PEG bowel-cleansing regimens with high-volume PEG regimens, all administered as a split dose. The primary outcome was rate of adequate bowel cleansing in the overall and right colon, and the secondary outcome was adenoma detection rate. Patient adherence, tolerability, and willingness to repeat the regimen were the primary tolerability outcomes. The results of the review and meta-analysis were published Nov. 1 by Clinical Gastroenterology and Hepatology.

Seventeen trials involving 7,528 patients were included in the meta-analysis. A total of 3,749 patients received low-volume split-dose preparations and 3,779 received high-volume split-dose preparations. No significant between-group differences were seen for low-volume versus high-volume regimens in adequacy of bowel cleansing (86.1% vs. 87.4%, respectively), with a pooled relative risk (RR) of 1.00 (95% CI, 0.98 to 1.02). Low-volume regimens had higher odds for adherence or completion (13 studies; RR, 1.06; 95% CI, 1.02 to 1.10), tolerability (9 studies; RR, 1.39; 95% CI, 1.12 to 1.74), and willingness to repeat the regimen (4 studies; RR, 1.41; 95% CI, 1.20 to 1.66). No significant difference was seen in adenoma detection rate (4 studies; RR, 0.96; 95% CI, 0.87 to 1.08). Overall, the quality of the evidence was considered moderate.

Among other limitations, the authors noted that the trials in the meta-analysis excluded patients with major comorbid conditions. “Thus, caution is required when prescribing these agents to frail or severely-ill patients, whereas the isotonic high-volume regimens may be a safer choice,” they wrote. This selection bias may also apply to hospitalized patients, patients in whom previous preparation regimens have failed, those with previous resections, and those who are severely constipated or who have been treated with opioids, the authors said.

However, they concluded that low- and high-volume split-dose preparations are equally effective for cleansing the overall colon and the right colon before colonoscopy and that the former led to a better patient experience, with more patients expressing willingness to repeat it. “When coupling the equivalent efficacy with a better experience, there is compelling evidence to recommend a low-volume split regimen as an alternative to the high-volume regimen, unless additional factors, such as cost or patient preferences, supports a different choice,” the authors wrote.