Potential clinical complications of Orise™ gel use, a new submucosal lifting agent: experience from a tertiary care center and review of the literature.

Background: Endoscopic mucosal resection (EMR) involves forming a fluid cushion in the submucosal area with a lifting agent, followed by superficial resection. Orise™ gel is one of the commonly used lifting agents for EMR. We present a case series and literature review that analyzes the characteristic histopathological findings and clinical implications observed where Orise™ gel was used before EMR. Methods: Colon resection specimens and prior EMR specimens where Orise™ gel was used were reviewed for patients undergoing EMR between January 2018 and December 2020. The literature review included relevant studies from the Medline and Cochrane databases from January 2018 to December 2020. Results: A total of 12 colon polyp EMRs using Orise gel were performed during the study period. Seven patients (58.34%) underwent surgical resection. Histological examination revealed that, after the EMR procedure, the Orise™ gel material changed its morphological characteristics over time from a basophilic (bluish) non-inflamed pattern to an eosinophilic (pink) type pattern, eliciting a foreign body reaction. The endoscopic appearance and examination of the excised specimens weeks after injection gave the impression of a mass in some cases. The material was also present transmurally and in some cases in the peri-intestinal adipose tissue. Conclusions: It was observed that Orise™ gel use elicits a foreign body-type granulomatous reaction. This potential side effect may lead to overdiagnosis of a mass/lesion and unnecessary surgical interventions. This case series and review of the literature aims to increase awareness of the changes caused by Orise™ gel in the gastrointestinal tract.