A prospective study of endoscopist-blinded colonoscopy withdrawal times and polyp detection rates in a tertiary...

Studies have suggested that a colonoscopy withdrawal time of at least 6 minutes is associated with an increased adenoma detection rate in patients undergoing colorectal cancer screening.

We aimed to determine colonoscopy withdrawal time and rate of polyp detection in a blinded study--conducted at Christchurch Hospital (Christchurch, New Zealand)--to determine if there was a relationship.

All 16 consultant endoscopists performing colonoscopy in a tertiary hospital had their withdrawal time from the caecum prospectively timed over 208 consecutive procedures between 11 April 2007 and 19 May 2007. The following data was collected: indication for procedure, final diagnosis, polypectomy rate, procedures performed and withdrawal time were recorded. Histology results were reviewed for all patients.

111 (53%) of colonoscopies were performed for symptom assessment and 97 (47%) for surveillance. There was significant heterogeneity between colonoscopists' withdrawal times (p<0.001). Polyps were diagnosed in 65 of all colonoscopies (31.3%). Of the screening colonoscopies polyps were found in 38 (39.1%) of which 14 were adenomas (adenoma detection rate of 14%). The median colonoscopy withdrawal time was 3 minutes 16 seconds when no polyps were found (range 5 seconds to 11 minutes 50 seconds). The median colonoscopy time when polyps were found was 8 minutes 31 seconds which included time taken for procedures (range 2 minutes 7 seconds to 35 minutes 40 seconds), p<0.001.

This study confirms that more adenomas were found by those endoscopists who had slower withdrawal times. Also colonoscopy withdrawal times are inherently much faster than recommended and highlights the importance of regular adenoma detection rate and withdrawal time auditing.