Impact of endoscopist withdrawal speed on polyp yield: implications for optimal colonoscopy withdrawal time

Background In 2002, a U.S. Multi-Society Task Force on Colorectal Cancer recommended that the withdrawal phase for colonoscopy should average at least 6-10 min. This was based on 10 consecutive colonoscopies by two endoscopists with different adenoma miss rates. Aims To characterize the relationship between endoscopist withdrawal time and polyp detection at colonoscopy, and to determine the withdrawal time that corresponds to the median polyp detection rate. Design Procedural data from out-patient colonoscopies performed at the Mayo Clinic, Rochester during 2003 were reviewed. Endoscopists were characterized by their mean withdrawal time for a negative procedure and individual polyp detection rate. Results A total of 10 955 colonoscopies performed by 43 endoscopists were analysed. Median withdrawal time was 6.3 min (range: 4.2-11.9); polyp detection rate was 44.0% (all polyps), 29.8% (<= 5 mm), 5.9% (6-9 mm), 6.7% (10-19 mm), 2.1% (>= 20 mm). Longer withdrawal time was associated with higher polyp detection rate (r = 0.76; P < 0.0001); this relationship weakened for larger polyps (r = 0.19 for polyps 6-9 mm, r = 0.28 for polyps 10-19 mm, r = 0.02 for polyps >= 20 mm). Overall median polyp detection rate corresponded to a withdrawal time of 6.7 min. Conclusion Our findings support a colonoscopy withdrawal time of at least 7 min, which correlates with higher colon polyp detection rates.