550 Discordance in Colorectal Polyp Size Determination Between Colonoscopy and Pathology Reporting

Abstract

INTRODUCTION: National guidelines recommend that patients with colorectal adenomas ≥1cm undergo surveillance colonoscopy to prevent colorectal cancer. Polyp size is often assessed twice, once during colonoscopy and again during pathology examination. It remains unclear whether these measurements vary and which should govern surveillance intervals. METHODS: We retrospectively analyzed a random sample of primary care patients who underwent polypectomy between January 1, 2013 and January 1, 2016 in a large academic healthcare center. Chart abstractors reviewed electronic health record data for colonoscopic polyp descriptors and measurements, corresponding pathology measurements, and histology. We excluded cases with normal histology, missing pathology, fragments, unreliable polyp matches between reports, and >5 polypectomies. We performed a paired t-test to assess polyp size discordance between reports and calculated Cohen's kappa coefficient to assess agreement whether the size was ≥1 cm. RESULTS: We reviewed 1,528 patient charts, and 831 (54.4%) met inclusion criteria, representing 1,532 polyps. Sizes ranged from 0.1-3.0cm on colonoscopy and 0.1-2.7cm on pathology reports. On colonoscopy report, the majority (881, 57.5%) used only a descriptive term rather than a numeric value to describe size (Table 1). Descriptive size terms were diminutive (513), tiny (39), small (328), and large (1). Only 2.8% of polyps described as diminutive, small, or tiny on the colonoscopy report were ≥1cm on the corresponding pathology report. Among the 367 (24.0%) polyps with discrete numeric sizes on both reports, size discordance varied by >0.2 cm for 50% of polyps (Figure 1). More of these polyps were ≥1 cm on colonoscopy (70) than on pathology (51) report, and there was remarkable clustering at 1 cm by colonoscopy report estimation (Figure 2). There was moderate agreement (kappa = 0.52) on size ≥1 cm. Among tubular adenomas (TA) ≥1 cm on colonoscopy or pathology report (36), 10 (27.8%) were ≥1 cm on both, 18 (50.0%) were ≥1 cm on colonoscopy only, and 8 (22.2%) were ≥1 cm on pathology only. CONCLUSION: There is considerable discordance between colonoscopic and pathology polyp size measurements, with more polyps sized as ≥1 cm by colonoscopic estimation compared to pathology, which has implications for surveillance frequency. Future studies should investigate the implications of discordant measurements on clinical outcomes and inform guidelines on surveillance intervals.