Underwater EMR of a circumferential periappendiceal polyp extending into the appendiceal orifice.
Key technical lessons:
▪ Be patient with underwater visualization—continue irrigating until the cecum is completely flooded.
▪ Adequate immersion allows the intraluminal appendiceal component to float into view, revealing the true extent of the lesion.
▪ Anchor the snare tip beyond the lesion, then gradually open the snare to capture as much tissue as safely possible.
▪ Before transection, confirm that the closed snare includes a rim of normal mucosa beyond the lesion margin.
▪ Carefully inspect the appendiceal lumen after resection to exclude residual adenomatous tissue.
▪ When closing the defect, preserve the appendiceal orifice and avoid clipping it shut to reduce the risk of delayed appendicitis.
Key message: successful underwater EMR requires patience, complete immersion, deliberate snare positioning, and preservation of appendiceal drainage.