Barclay RL et al. (2006) Colonoscopic withdrawal times and adenoma detection during screening colonoscopy. N Engl J Med 355: 2533–2541

Colonoscopy is increasingly being used to screen for neoplasia; however, several population-based studies have shown inter-examiner variation in the detection of lesions, possibly attributable to the technique used for withdrawal of the colonoscope—the key phase at which neoplasia can be identified.

Researchers from the University of Illinois College of Medicine at Rockford, carried out a large community-based study to examine the relationship between time taken to withdraw the colonoscope and neoplasia detection in everyday practice. For 2,053 screening examinations carried out by 12 experienced gastroenterologists, the researchers recorded the number, size and histologic features of all neoplastic lesions detected. The times taken to insert and withdraw the colonoscope were also recorded for each procedure.

Neoplastic lesions were identified in 23.5% of the study population. The rate of lesion detection differed greatly between gastroenterologists; the mean number of lesions identified per subject screened ranged from 0.10 to 1.05. Time taken to withdraw the colonoscope also showed wide variation between examiners, ranging from 3.1 min to 16.8 min for procedures during which no polyps were removed. Overall, those gastroenterologists with mean withdrawal times of 6 min or more had significantly higher rates of detection of any neoplasia (28.3% vs 11.8%; P <0.001) and of advanced neoplasia (6.4% vs 2.6%; P = 0.005) than those with mean withdrawal times of less than 6 min. Given the small size of this study the results cannot be extrapolated to wider colonoscopic practice, but the authors suggest that they might inform future screening strategies.