Colonoscopy by a family physician: detecting proximal neoplasia in asymptomatic adults

Flexible sigmoidoscopy (FS) is considered an adequate screening test in average risk (AR) patients. The purpose of this study was to determine the diagnostic yield of FS in detecting colonic neoplasia between AR and high risk (HR) patients. We present a chart review of 559 outpatient colonoscopies performed by a family physician from September 2003 to October 2007. The prevalence of neoplasia and diagnostic yield of FS was compared between groups. The overall prevalence of neoplasia was 23.1% (AR) and 32.8% (HR); p = 0.02. The prevalence of proximal neoplasia not detectable by FS was 10.2% (AR) and 14.5% (HR); p = 0.16. The diagnostic yield of FS in each group was 56%; FS would have missed 44% of polyps regardless of patient risk. The high rate of colonic neoplasia not detected by FS (44%) suggests that FS alone is inadequate for screening in AR patients.