Endoscopy 2013; 45(01): 73
DOI: 10.1055/s-0032-1325772
Letters to the editor
© Georg Thieme Verlag KG Stuttgart · New York

Monitoring colonoscopy withdrawal times remains important

M. D. Rutter
A. Chilton
J. Patnick
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Publication History

Publication Date:
19 December 2012 (online)

We read the recent paper on colonoscopy withdrawal time (CWT) with interest [1]. In the English Bowel Cancer Screening Programme, a diagnostic withdrawal time of at least 6 minutes remains a key quality metric for colonoscopic performance [2]. We feel that it is an important standard, as it helps to protect against the poor practice of rapid withdrawal without proper mucosal inspection. Although a slow withdrawal time is not the only aspect of a gold standard inspection technique, it remains one of its key principles.

In their introduction, the authors quote two papers supporting their argument that withdrawal time is not a useful quality indicator [3] [4]. However it is important to point out that in the study by Taber & Romagnuolo there was a statistically significant correlation between polyp detection rate and longer procedure time. Likewise in the study by Gellad et al., there was a significant correlation between CWT and adenoma detection rate (ADR). Moreover, in Moritz et al.’s study colonoscopists with a longer median CWT had a 21 % greater ADR, although this did not reach statistical significance (odds ratio [OR] 1.21, 95 % confidence interval [CI] 0.94 – 1.56; P = 0.14). Also, 85 % of colonoscopists in this study already had a median CWT of more than 6 minutes. Although this was a large study, this may represent a type II error, particularly given that other studies have shown a positive correlation.

As a standard, colonoscopic withdrawal time is particularly useful in two situations:

  1. As a supportive/explanatory tool when an individual’s adenoma detection rate falls below (or is close to) the agreed standard – we have often found that this allows the colonoscopist to reflect on and adjust their extubation technique.

  2. As a quality indicator for diagnostic technique in patient cohorts where the adenoma detection rate standard is either not appropriate or cannot be applied – for example colitis surveillance or if an individual’s practice comprises predominantly young patients.

We, like others, have found a clear correlation between a slow inspection of the mucosa on extubation and adenoma detection rate [5]. We feel it is important for good colonoscopic practice to uphold this valuable principle of diagnostic technique and quality metric.