Graduated injection needles and snares for polypectomy are useful for measuring colorectal polyp size

Abstract

Background: Accurate measurement of polyp size during colonoscopy is important: however, visual estimation of polyp size is inaccurate, and it is cumbersome to use additional accessories to measure polyp size whenever polyps are detected. Aims: To evaluate the accuracy and usefulness of graduated devices that can also be used for polypectomy. Methods: The ends of the outer sheath of the injection needles and snares were marked at intervals of 5 mm (total 30 mm). Four endoscopists measured 53 polyps of 36 patients in the following manner: visual estimation, estimation with biopsy forceps, and measurement with graduated devices. Actual size of all polyps measured through a calliper was used as reference standard. Results: The difference between actual size and size measured by visual estimation was statistically significant (1.27 mm, P<0.001), whilst the differences between actual size and size measured by biopsy forceps (0.06 mm, P=1.00) or graduated devices (0.15 mm, P=0.620) were not. The linear correlation between the estimates and the actual sizes showed that the graduated device gave the largest positive linear correlation (0.986, P<0.001) of the three measurement methods tested. Conclusions: The graduated devices are efficient methods when measuring polyp size and performing polypectomy in a single step.