The INTERPRET trial found that a 1-liter polyethylene glycol (PEG) plus ascorbate prep delivered better high-quality bowel cleansing than 2-L and 4-L formulations in hospitalized adults — and patients were more willing to repeat it. The findings challenge the long-held assumption that more volume means better results, even in difficult-to-prepare inpatients.
The "more is better" approach to inpatient bowel prep may be due for a rethink. The randomized INTERPRET trial, published in Annals of Internal Medicine, found that a split-dose 1-liter PEG plus ascorbate regimen achieved comparable overall cleansing — and significantly better high-quality cleansing — compared to 2-L and 4-L preparations in stable hospitalized adults undergoing elective colonoscopy. Patients in the 1-L group were also more willing to repeat the prep.
Hospitalized patients are notoriously harder to prepare for colonoscopy due to age, reduced mobility, comorbidities, and medications that impair bowel function. Despite this, current 2025 US guidelines still recommend high-volume PEG for inpatients — a recommendation based on low-quality, outpatient-derived evidence. The trial's lead author believes these results will push practice toward lower-volume, patient-centered protocols.
By the Numbers:
Why it matters: Poor bowel prep in inpatients leads to missed lesions, repeat procedures, longer hospital stays, and higher costs. This trial offers strong evidence that a lower-volume regimen can improve both quality and patient experience — without adding burden.
