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Effective Endoscopic Delineation With Acetic Acid Spray and Narrow Band Imaging in Underwater Endoscopic Mucosal Resection for Sessile Serrated Lesion

Yabuuchi, Yohei MD1; Hosotani, Kazuya MD1; Morita, Shuko MD1; Imai, Kenichiro MD2; Hotta, Kinichi MD2; Inokuma, Tetsuro MD, PhD1

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The American Journal of Gastroenterology: June 2022 - Volume 117 - Issue 6 - p 840
doi: 10.14309/ajg.0000000000001694

Sessile serrated lesions (SSL) have gained attention due to a reportedly increased risk of cancer development and increasing therapeutic opportunities. However, incomplete resection is more likely in SSL than adenomas due to the difficult delineation. Acetic acid spray was applied under narrow band imaging (NBI) in underwater endoscopic mucosal resection (UEMR) to overcome this problem. A 50-year-old woman underwent a screening colonoscopy. A 14-mm flat and isocolored lesion, covered with a mucus cap, was identified in the transverse colon (a). The lesion had unclear margins on white light imaging and NBI alone (b). Spraying 3% acetic acid solution made it easier to detect and determine the lesion margins on NBI (c). Magnifying observation with NBI revealed a uniform pit pattern, suggesting the absence of dysplasia. Thus, UEMR was performed (d). En bloc resection was achieved (e). A histopathological examination showed an SSL with negative resection margins (f). This technique provided 3 advantages. First, the acetic acid spray with NBI distinguished SSL from the surrounding mucosa because of the acetowhitening reaction. Second, the acetic acid spray with NBI enhanced the pit structure under magnification, and this allowed predicting the presence of dysplasia. However, this is not always possible because the magnifying endoscopy technology is not available in many settings. Third, the effective delineation of SSL by combining underwater observation, acetic acid spray, and NBI enabled margin-free resection by UEMR. This achieved a significantly higher R0 resection rate for lesions larger than 10 mm compared with conventional EMR, and unnecessary surveillance by piecemeal resection could be avoided. If the lesion showed no findings of dysplasia and was small enough to be resected en bloc, cold techniques, such as cold snare polypectomy and cold EMR, which have a lower risk of postpolypectomy bleeding, could be considered. In summary, the combined use of acetic acid spray and NBI distinguished SSL, and subsequent UEMR enabled the complete resection of SSL larger than 10 mm. Watch the video at (Informed consent was obtained from the patient to publish these images.)

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