Bowel Bubble Formation with Oral Sulfate Solution for Colonoscopy Bowel Preparation Using Same-Day and Split-Day Regimens: The B-BOSS Study.

Background and Objectives: Bowel bubble formation during colonoscopy can impair mucosal visualization and reduce procedural efficiency. However, its clinical significance remains incompletely characterized. This study aimed to evaluate the prevalence of severe bowel bubbles in the proximal colon and their impact on colonoscopic quality in patients undergoing bowel preparation with oral sulfate solution (OSS), using either a same-day regimen (SAR) with 480 mL OSS or a split-day regimen (SPR) with 960 mL OSS. Methods: This retrospective study was conducted between October 2024 and December 2025 across two affiliated institutions. Patients who underwent colonoscopy with OSS-based bowel preparation were included. SAR was used for screening, symptomatic evaluation, and surveillance colonoscopy. SPR was applied exclusively to patients with a prior history of sodium picosulfate-related abdominal pain or inadequate bowel preparation with SAR. Sodium picosulfate was prescribed on the day before colonoscopy in the SAR group and a low-residual diet was administered in both the SAR and SPR groups. The prevalence of severe bubbles in the proximal colon was evaluated, and their impact on colonoscopic quality was examined. Results: A total of 176 SAR cases and 51 SPR cases were analyzed. The rate of severe bubbles in the proximal colon was identical between both regimens (17.6%). Compared with cases without severe bubbles, those with severe bubbles had significantly longer cecal insertion times (median [IQR]: 7.0 [5.0-10.0] vs. 9.0 [7.0-13.0] min, p = 0.018) and total procedure time (20.0 [16.0-25.0] vs. 24.0 [19.0-30.0] min, p = 0.024). Preparation-to-colonoscopy time was also longer in cases with severe bubbles (5.0 [4.0-5.5] vs. 5.0 [5.0-6.0] h, p = 0.041). Adenoma detection rates were 73.2% in cases without severe bubbles and 67.5% in those with severe bubbles (p = 0.571). Conclusions: Severe bowel bubble formation tended to be associated with longer cecal insertion and total procedure times, and was more frequently observed with a longer preparation-to-colonoscopy interval.