The newly developed 1L polyethylene glycol with ascorbate (PEG-ASC) solution (CleanviewAl; Taejoon, Seoul, South Korea) offers the advantage of reduced volume for colonoscopy bowel preparation. However, the high content of sodium ascorbate and sodium sulfate in the solution raises concerns about potential hypernatremia. This study aimed to compare the efficacy and safety of the 1L PEG-ASC preparation when administered with 1L versus 2L of additional water in patients undergoing screening or diagnostic colonoscopy

This study was a prospective, consecutive enrollment of patients undergoing screening or diagnostic colonoscopy across three Korean academic hospitals. Patients were randomly assigned to one of two groups: the 1L group (n=87) ingested 1L of PEG-ASC solution and 1L of water, and the 2L group (n=83) ingested 1L of PEG-ASC solution and 2L of water. The primary endpoints were the assessment of overall bowel cleansing success and right colon cleansing using the Boston Bowel Preparation Scale (BBPS). The secondary endpoints were the evaluation of tolerability and safety (including treatment-related adverse events and changes in serum electrolytes/renal function).

A total of 170 patients were enrolled. The two groups were comparable in terms of gender ($p=0.233$) and age ($p=0.917$). There were no significant differences in the mean overall BBPS score or the right colon BBPS score between the 1L and 2L groups, indicating comparable cleansing efficacy. Interestingly, the polyp detection rate (PDR), and specifically the detection of polyps larger than 1cm, was higher in the 1L group compared to the 2L group. However, there was no difference in the number of polyps detected in the right colon. The difficulty of ingestion (tolerability) was reported as easier in the 1L group. Subgroup analysis revealed no significant changes in serum BUN, creatinine, sodium, potassium, and chloride levels between the two groups. In terms of treatment-related adverse events, thirst was more frequent in the 1L group, while vomiting was more frequent in the 2L group. All reported adverse events were self-limited and recovered without intervention.

The study found no significant difference in bowel preparation efficacy or overall safety between ingesting 1L or 2L of water in conjunction with the 1L PEG-ASC solution. The 1L water intake regimen was associated with better tolerability (easier ingestion) and an unexpectedly higher polyp detection rate. Therefore, the lower-volume water intake regimen (1L water) may be preferable, but the choice of bowel preparation method should ultimately be tailored to the specific needs and preferences of each patient.