Endoscopic mucosal resection: tips and tricks for gastrointestinal trainees

Endoscopic mucosal resection (EMR) is a minimally invasive, specialized endoscopic technique that is useful in resecting superficial gastrointestinal lesions that are unable to be removed by standard polypectomy. This is typically accomplished using a submucosal injection that lifts the lesion away from the muscularis propria to allow for safe resection of the polyp, either via piecemeal or en bloc resection. Over the years, several techniques exist to perform EMR including conventional EMR or hot EMR, cold EMR and underwater EMR. Despite its established advantages and safety over conventional techniques such as surgery, the adoption of endoscopic resection (and thus the education and training of gastroenterology trainees) is lagging. The goal of this article is to offer a comprehensive review of the basic principles of colonic EMR. We review the concepts of optical diagnosis including the various polyp classification systems available to determine the polyp morphology and histology. We also discuss the technical aspects of performing colonic EMR. We also outline the common adverse events associated with EMR including bleeding, perforation, postpolypectomy syndrome, and residual or recurrent polyps, and discuss preventative measures that can be taken to mitigate adverse events. Lastly, we offer practical tips for trainees who want to undertake EMR in their clinical practice.