Postpolypectomy electrocoagulation syndrome after removal of a large sessile colon polyp

A) Normally, the snare extends beyond the polyp, and the tip contacts mucosa behind the polyp (point a). B) As the snare is closed, the tip may catch on the mucosa behind the polyp (point a) and draw it toward the polyp. The submucosa is bunched up into the snare, but the entrapped mucosa cannot be seen because it is hidden behind the polyp. Cutting through a broad based polyp may also transfer sufficient thermal energy to the deeper layers to result in a transmural burn. C) After polypectomy, there is a large defect, and the wall beneath the area of denuded mucosa is thinner and more liable to conduct electrical energy (heat) to the serosal surface causing deep thermal damage, resulting in the postpolypectomy electrocoagulation syndrome.