Downsizing the target: the underwater closure technique.

A 77-year-old man with a 3-cm slightly elevated, nongranular type, laterally spreading tumor (LST-NG 0-IIa) of the sigmoid colon was referred to our institute for endoscopic resection (●" Fig.1). Piecemeal underwater endoscopic mucosal resection (UEMR) was carried out with a high definition narrow band endoscope (CF-H190L; Olympus Europa SE, Hamburg, Germany). After UEMR, the margins were ablated using argon plasma coagulation. Histology revealed an adenomatous polyp with high grade dysplasia and free deep resection margins. Because of the patient’s need to resume antiplatelet therapy with clopidogrel, prophylactic closure of the resection site was carried out. After water infusion, the resection borders “floated,” and there was a significant reduction in the size of the resection defect (●" Video1). Opened biopsy forceps (Radial Jaw 4; Boston Scientific Corp, Natick, Massachusetts, USA), which were placed over the post-polypectomy ulcer before and after water infusion, clearly confirmed that there was a reduction in the size of the resection defect (●" Fig.2). In viewof the downsizing, the underwater closure technique was applied. By “floating” the mucosa and submucosa away from the deeper muscularis layer [1], underwater closure allowed an easier apposition of the resection borders with complete closure of the resection defect using only two endoclips (Instinct clip; Cook Fig.1 Endoscopic images showing a laterally spreading tumor in the sigmoid colon of a 77-year-old man as seen: a under high definition white light; b with narrow band imaging; and c underwater.