Time to Confirmed Completion of Bowel Preparation as a Preprocedural Indicator of Colonoscope Insertion Difficulty: A Prospective Observational Study.

Background and Aims: Runway time, defined as the interval between completion of polyethylene glycol ingestion and the start of colonoscopy, has been studied as a determinant of bowel cleansing quality. However, whether the bowel preparation course itself is associated with colonoscope insertion difficulty remains unclear. We aimed to examine the associations of bowel preparation course indicators with cecal intubation time (CIT) and loop formation. Methods: In this single-center prospective observational study, we enrolled consecutive patients undergoing unsedated colonoscopy and prospectively recorded four bowel preparation course indicators: time to first bowel movement, time to confirmed completion of bowel preparation, total number of bowel movements, and estimated stool volume. Multivariable linear regression analysis was performed using log-transformed CIT as the dependent variable and adjusting for age, sex, body mass index (BMI), and endoscopist. Associations with loop formation were examined using multivariable logistic regression analysis adjusted for age, BMI, and endoscopist. Results: A total of 185 patients were included. Among the four indicators, only the time to confirmed completion of bowel preparation was associated with insertion difficulty. In multivariable linear regression analysis, each 30-min increase in time to confirmed completion of bowel preparation was associated with longer CIT (exp(β), 1.139; 95% confidence interval [CI], 1.065-1.219). In multivariable logistic regression analysis, it was also associated with loop formation (odds ratio, 1.624; 95% CI, 1.129-2.360, per 30-min increase). Conclusions: Time to confirmed completion of bowel preparation may serve as a simple preprocedural indicator of colonoscope insertion difficulty. Trial Registration: N/A.