Lower volume bowel preparation as effective and safe as higher volume regimen for inpatient colonoscopy: Study

A randomized controlled trial compared the efficacy, tolerability, and safety of different volumes of polyethylene glycol (PEG) regimens for bowel preparation for inpatient colonoscopy.

The study found that a 1 L PEG-ascorbate regimen provided effective and high-quality bowel cleansing and was associated with a greater willingness to repeat the regimen than 2 L PEG and 4 L PEG regimens. The findings support adopting a low-volume regimen to improve completion rates and patient tolerability while preserving cleansing quality.

The study is published in Annals of Internal Medicine.

Researchers from the University of Bologna and colleagues conducted the INTERPRET trial (INpatienTs bowEl pReParation RandomizEd Trial) to better address the evidence gap around adequate bowel preparation among hospitalized patients undergoing elective colonoscopy.

Between June 2021 and January 2025, the researchers randomly assigned 665 patients across seven hospitals in Italy to receive a 1 L, 2 L, or 4 L PEG solution before their procedure, and endoscopists assessed bowel cleanliness without knowing which preparation was used. While all three regimens produced similar rates of adequate cleansing, the 1 L regimen resulted in higher-quality cleansing overall, including in the right side of the colon, where inadequate preparation increases the risk of missed lesions.

The findings suggest that lower-volume preparation may be an effective and acceptable option for inpatient colonoscopy. Whether these findings are generalizable to outpatients warrants future research.

Reference:

Leonardo Frazzoni, Paola Cesaro, Franco Radaelli, et al. Low-Volume Polyethylene Glycol for Bowel Preparation in Hospitalized Adults: A Multicenter Randomized Trial. Ann Intern Med. [Epub 5 May 2026]. doi:10.7326/ANNALS-25-05005