Reply to Liu et al.

10.1055/a-2736-7661

We thank Drs. Wanqi Liu and Guang Ji for their interest in our work [1] and their constructive comments, which we address below. The authors correctly point out that optimal efficacy is achieved with a runway time of 4–6 hours before colonoscopy, with recent literature suggesting that a shorter interval of 2–4 hours may be even more effective [2]. In our study, participants were instructed to start the second dose 4 hours before colonoscopy and to finish no later than 2 hours before the procedure. We therefore believe that the applied regimen aligns with current evidence. Nonetheless, future studies should assess patient-reported runway time and potential barriers in more detail.

Regarding colonoscopy timing, we agree that same-day preparation may be appropriate for afternoon procedures, while a split-dose regimen remains the standard for morning colonoscopies [3] [4]. Early morning procedures may be challenging for patients and their willingness to repeat the bowel preparation and colonoscopy. Given the randomized design and large sample size, colonoscopy timing was likely balanced between the two groups.

We acknowledge the authors’ point on total fluid intake. As this variable did not meet the multicollinearity assumption in regression analyses, we were unable to include it as an independent predictor.

Finally, we used the validated Mayo Florida Bowel Preparation Tolerability Questionnaire, which was the only validated tool available during protocol design. While other Likert-based instruments have since emerged [5], we adhered to the original wording. As the primary outcomes did not differ significantly between the groups, any potential influence on our results is likely to be only minimal.

To conclude, our study aimed to investigate the efficacy of a 1L bowel preparation regimen and to multidimensionally assess the factors that drive the tolerability of bowel preparation. Incorporating patient experience into preparation strategies remains, in our opinion, essential to optimize colonoscopy quality and patient adherence.

Publication History

Article published online:
22 January 2026

• References

• 1 van Riswijk MLM, Indemans FA, Hawinkels K. et al. Comparing low volume versus intermediate volume bowel preparation and their impact on work and tolerability: an open-label, noninferiority randomized controlled trial. Endoscopy 2025;
• 2 Kim HM, Kim HS, An YE. et al. Effect of bowel preparation completion time on bowel cleansing efficacy: Prospective randomized controlled trial of different bowel preparation completion times precolonoscopy. Dig Endosc 2024; 36: 1347-1354
• 3 Pasquale L, Grande G, Zagari RM. et al. Day before late regimen vs standard split dose of low-volume PEG-CS for early morning colonoscopy: Multicenter randomized controlled trial. Endosc Int Open 2025; 13: a25158539
• 4 Martel M, Barkun AN, Menard C. et al. Split-dose preparations are superior to day-before bowel cleansing regimens: a meta-analysis. Gastroenterology 2015; 149: 79-88
• 5 Tontini G, Spada C, Radaelli F. et al. Bowel preparation for colonoscopy: the patient point of view. Dig Dis 2025;