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10.1055/a-2695-0994

We read with great interest the article by van Riswijk et al. [1] comparing 2L polyethylene glycol with ascorbate (2L PEG+Asc) versus 1L with added sodium sulfate (1L PEG+Asc) for bowel preparation. The trial concluded that 1L PEG+Asc was noninferior to 2L PEG+Asc in terms of effective cleansing and associated with higher willingness to repeat; however, there are some issues that we would like to explore.

First, runway time (the interval between the last dose and the examination) may warrant further consideration. Some studies have indicated that the superiority of split-dose bowel preparation regimens is only maintained within an appropriate runway time and have recommended the "golden 5 hours" [2]. The study necessitated that participants complete the final dose a minimum of 2 hours prior to hospital arrival. Further evaluation of runway time may enhance the persuasiveness of the findings.

Second, there are differing opinions regarding the timing of colonoscopies (morning vs. afternoon). A study has indicated that patients undergoing a colonoscopy in the morning were less likely to adhere to the split-dose bowel preparation regimen [3]. Another study suggested however that adenoma detection rates were significantly higher for morning colonoscopies than for afternoon procedures [4]. Further refinement of the assessment of colonoscopy timing may be beneficial.

Third, when conducting regression analysis of willingness to repeat the bowel preparation regimen, total fluid intake should perhaps have been incorporated alongside the other variables, as the study permitted additional fluid consumption. Fluid volume is a significant factor influencing the finding of participants' tolerability and willingness to repeat [5]. Furthermore, the article did not provide detailed criteria for classifying the “good,” “fair,” and “difficult” variable in the Mayo Florida Bowel Preparation Tolerability Questionnaire (MBTQ), which significantly impacts the willingness to repeat.

Finally, we appreciate the authors' efforts in exploring superior bowel preparation protocols and look forward to the development of further practical methods to enhance the efficacy of bowel preparation and reduce barriers to colonoscopy.

Publication History

Article published online:
22 January 2026

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Letter to this article:Reply to Liu et al.Endoscopy 2026; 58(02): 216-216
DOI: 10.1055/a-2749-8151