Comparison of Cecal Intubation Rates and Quality of Bowel Preparation Between Morning and Afternoon Colonoscopies

Abstract

Background/Aims: The timing of colonoscopies has been reported predictive factor of incomplete colonoscopy and poor bowel preparation. We aimed to compare the cecal intubation rates and quality of bowel preparation in morning versus afternoon procedure, and to determine the interval time between polyethylene glycol (PEG) solution starting time and colonoscopy procedure for adequate bowel preparation. Methods: A prospective, case-control, and single-center study comparing cecal intubation rates and quality of bowel preparation according to the timing of procedure were performed between May 2007 and October 2007. Outpatients in the morning and afternoon procedure were advised to drink PEG solution at 5 AM and at 8 AM on the day of colonoscopy, respectively. Quality of bowel preparation was assessed using the Ottawa bowel preparation quality scale. Results: A total of 300 outpatients were enrolled, of which 149 in the morning and 151 were in the afternoon. Several known factors of incomplete colonoscopy, such as female gender, prior hysterectomy, constipation, low body mass index, and diverticulosis were similar between two groups. Complete cecal intubation rates were 97.3% (145/149) in the morning group and 98.0% (148/151) in the afternoon group, and were not significant difference (p = 0.69). Poor bowel preparation rates in the morning versus afternoon were 14.8% versus 13.9% (p = 0.81). Subjects with interval time ≥7 hours between PEG starting time and procedure starting time had an 2.10 odds ratio (95% CI, 1.08-4.07, p <0.05) with poor preparation, compared to those with interval time 4-7 hours. Conclusions: Contrary to the previous studies, complete cecal intubation rates and bowel preparation rates are not different in the morning versus afternoon procedures. We suggest that to improve the adequate bowel preparation rate of afternoon colonoscopy, it is better to perform the colonoscopy within 4-7 hours after PEG starting time.