Risk factors for inadequate bowel preparation before colonoscopy: A retrospective cohort study

Bowel preparation is a critical step in colonoscopy and endoscopic surgery. Adequate and effective bowel cleansing significantly improves lesion detection rates while reducing operative risks and complications.

To investigate the current state of inadequate bowel preparation in patients undergoing colonoscopy, identify the contributing factors, and develop interventions.

This study was designed as a retrospective cohort study. A convenience sampling method was used to select 484 patients who underwent colonoscopy at Beijing Chao-Yang Hospital, Capital Medical University, from October 2023 to October 2024. General patient data, disease-related variables, and the Boston bowel preparation scale were collected. Logistic regression analysis was conducted to identify the factors associated with inadequate bowel preparation.

Among the 484 patients, the rate of inadequate bowel preparation was 25.8% (125/484). Influential factors for poor bowel preparation included history of colorectal surgery [odds ratio (OR) = 5.814], low-residue diet 1 day prior (OR = 0.145), time interval from last dose to start of examination (OR = 1.447), total exercise time after medication (OR = 0.992), and total number of bowel movements after medication (OR = 0.900) (all P < 0.05).

This study highlights several modifiable and non-modifiable factors influencing bowel preparation, such as surgical history and behavioral adherence. The findings support implementing dietary adjustments, optimized laxative timing, physical activity guidance, and tailored strategies for high-risk patients to improve bowel cleansing and enhance the diagnostic accuracy of colonoscopy.