PWE-011 Withdrawal time correlates with detection of tubular adenomas but not sessile serrated polyps

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One of the earliest key performance indicators was a withdrawal time greater than 6 mins. A previous study from our audit process (2000–2010 – 67 570 procedures) showed that withdrawal time was correlated with% of procedures where polyps were detected (r=42, p=0.03) NZMJ 2013; 126:25–35. Polyp detection over the audit period (2000–2010) increased from 29% in 2000 to 49% in 2010. Withdrawal time also increased from 5.6 mins in 2000 to 6.6 mins in 2010. Withdrawal times varied from 3.1mins to 11.2 mins for each endoscopist. Many publications have shown that encouraging longer withdrawal times (with feedback by an audit process) increases overall polyp detection and adenoma detection. Some doubt has been cast on the utility of withdrawal time as most endoscopists have now changed their practice and are meeting the 6 min threshold. The implication of this change may mean that other factors have now become more important for determining polyp detection. There is limited data on the correlation of withdrawal time and the detection of sessile serrated polyps (SSP).


There has been a continuous audit process from 2000–2016. This has included polyp histology from 2012. Withdrawal time is affected by the time taken for polypectomy and will increase as more polyps are detected and removed. Withdrawal time for procedures where no polyps are detected gives a more accurate indicator of the usual behaviour for a given endoscopist.


12555 procedures performed by 15 endoscopists were analysed. Mean withdrawal time was 8.3 mins (range 6.2 to 20.6 mins) and 65% of procedures had a polypectomy. There was a significant correlation between withdrawal time and the proportion of procedures with polyps detected (r=0.52, p=0.02). There was also a significant correlation between withdrawal time and% of procedures with adenomas detected (r=0.5 p=0.027). There was no correlation between withdrawal time and detection of SSP (r=0.11, p=ns.). There was no correlation between mean number of adenomas and withdrawal time.


A modest but significant correlation of polyp detection with withdrawal time has been maintained despite these evolving trends. The audit process may have helped increase withdrawal times overall but there continues to be a wide range of withdrawal times for individual endoscopists. The detection of SSPs appear to be a different skill that is not dependant on withdrawal time.

Disclosure of Interest

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