Background/Aims:
The colonoscopic withdrawal time has been proposed as a quality indicator for colonoscopy, and this is based on the recent evidence that the Colon withdrawal time is associated with adenoma detection rate. In this study, we examined the difference of the polyp detection rates between practicing endoscopists, and we analysed certain factors that might lead to such differences, and particularly the colonoscopic withdrawal time.

Methods:
We retrospectively evaluated the colonoscopic procedures that were performed by 7 second-year GI fellows at Hanyang University Guri Hospital. A total of 1,515 colonoscopies were assessed for the polyp detection rate, the insertion time, the withdrawal time, bowel preparation, the size of the detected polyps and the location of polyps.

Results:
The median withdrawal time for the case with no polyps removed was 3.6 to 7.1 minutes. There was a strong positive correlation between the colonoscopic withdrawal times and the polyp detection rates (p＜0.001). Furthermore, a longer withdrawal time resulted in discovering a higher percentage of small polyps. On comparing groups, the group of colonoscopists with a withdrawal time longer than 6 minutes had a higher rate of detecting polyps (30.7% vs 18.4%, p＜0.001).