Diagnostic Accuracy of Optical Detection of Residual Colorectal Neoplasia After Endoscopic Mucosal Resection: Impact of Endoclip Closure at EMR Site

Abstract

Introduction: Application of clips after EMR may reduce post EMR bleeding but also interfere with the recurrent adenoma detection at follow up due to nodular distortions of scar tissue. This could lead to an overtreatment of benign lesions. In a prospective trial, we aimed to evaluate the diagnostic accuracy of white light and narrow band imaging (NBI) with near-focus capability in recurrent adenoma detection with or without clip artifact. Methods: This prospective trial was started in January 2016 and is ongoing. Consecutive patients undergoing follow-up colonoscopy after a previous EMR of ≥20mm colorectal polyps were included. Endoscopists predicted the presence of neoplasia recurrence of EMR scars with or without clip artifact and their level of confidence (high or low) based on visual assessment of the previous EMR site subsequently with the four modalities 1) white light without and 2) with near-focus, and 3) NBI without and 4) with near-focus. Each EMR site was biopsied as a reference standard and histology assessed by a pathologist blinded to the endoscopist's visual assessment. Diagnostic accuracy was calculated for all diagnostic modalities for the real-time endoscopic assessment of the EMR scar tissue with or without clip artifacts. Results: A total of 172 patients (54% male, mean age: 65 years with 180 scar sites were included perprotocol, with a median follow up of 8 months (range: 3-71 months). At the original EMR, clips were used in 82/180 (45%) lesions. The rate of post-EMR scar clip artifact was 61% (50 of 82). Diagnostic accuracy for all EMR-scar sites with or without clip- artifact and confidence level in real time are shown at Table 1 and 2. The prevalence of residual neoplasia was 25% for all EMR scars. 27% of cases were over treated for benign disease when clips were used versus 8% of cases when clips were not used. Overall, clips reduced the proportion of high confidence diagnoses and appeared to lower the accuracy of EMR scar assessment in low confidence diagnoses but not for high confidence diagnoses.Table: Table. Diagnostic value of optical detection of residual neoplasia with or without clip artifactConclusion: These results suggest that clips used to close colonic EMR defects may impair the ability to accurately assess the EMR scar at follow up. Clips reduced the proportion of high confidence diagnoses as well as the accuracy of scar assessment in low confidence diagnoses, and furthermore, increased the proportion of over treated benign clip artifact. Alternative methods to potentially reduce post-EMR bleeding are needed.