Shorter preparation to procedure interval for colonoscopy improves quality of bowel cleansing

Background The timing of bowel preparation for colonoscopy influences the quality of bowel cleansing and the success of the procedure. Aim We aimed to determine whether the interval between the end of bowel preparation and the start of colonoscopy influences preparation quality. Methods We retrospectively analysed 1785 colonoscopies performed between January 2010 and January 2011. The quality of bowel cleansing was compared between those who had a less than 8-h interval between the end of bowel preparation to the start of the procedure versus those who had a greater than 8-h interval. Univariate and multivariate logistic regression analyses evaluated quality of bowel cleansing, preparation to procedure time, age, gender, hospital inpatient or outpatient status, indication for colonoscopy, caecal intubation rate, and segmental polyp detection. Results Fifty-three per cent of the cohort was male. Eighty-nine per cent were outpatients. Bowel cleansing was reported as satisfactory/good in 87% and poor in 13%. A <8-h preparation to procedure time was associated with a higher rate of satisfactory/good cleansing than a >8-h interval (odds ratio (OR) 1.3, P = 0.04). In a multivariate analysis, female gender (OR 1.4, P = 0.02), outpatient status (OR 3.1 P = 0.001) and indication for procedure (P < 0.01) were significant predictors of adequate bowel preparation. Adequate bowel preparation was associated with a significant increase in caecal intubation rates (OR 5.3, P = 0.001). Conclusions A shorter (<8h) interval between end of bowel preparation and start of colonoscopy yielded better bowel cleansing than a longer (>8h) interval. Adequate bowel preparation led to improved caecal intubation rates.