Endoscopists’ estimation of size should not determine surveillance of colonic polyps

Abstract

Current British Society of Gastroenterology guidelines use adenomatous polyp size as one of the key factors in determining polyp follow-up. This study aimed to compare polyp size assessment by colonoscopists and pathologists before and after fixation to determine the optimal method for measurement. Thirty-five colorectal polyps were found during pre-arranged colonoscopies in one centre. Polyp size was measured to the nearest 1 mm by three different methods: 1. by the endoscopist at colonoscopy; 2. by the pathologist fresh, following removal; 3. by the pathologist fixed, following fixation. The endoscopist and the pathologist were blinded to each other's measurements. Seventeen men, eighteen women with mean age of 66.2 years (SD: 9.4, range: 38.7-85.5) underwent polypectomy/s with all polyps removed intact. Polypectomies were performed by consultants (43%), nurse specialists (34%) and specialist registrars (23%). The median size (mm) of polyps measured were endoscopically, 6.5 (2-25 mm); fresh specimen 7.0 (4-28 mm) and fixed 7.0 (4-28 mm). Endoscopic measurements were significantly lower than that of fresh and fixed sizes (P < 0.001 and P = 0.003 respectively), with poor correlation [correlation of variance (CV): 21.0% and intraclass correlation coefficient (ICCC): 0.841 for endoscopic and fresh measurements; CV: 21.1% and ICCC: 0.838 for endoscopic and fixed measurements]. There was no statistical difference between fresh and fixed specimen measurements (P > 0.05; CV: 4.2%, ICCC: 0.974). In three patients, the endoscopic measurement was < 1 cm in polyps that were found to be >or= 1 cm on pathological measurement. Endoscopists consistently underestimated polyp size. Fixation had no effect on polyp size. Pathologists' measurement of polyp size on fixed specimens should determine the need for further colonoscopic follow-up.