eP502 Is endoscopic full thickness resection with over-the-scope clips suitable for polyps at the appendiceal orifice?

Background Endoscopic full thickness resection (EFTR) is an advanced endoscopic technique allowing for polypectomy when standard submucosal resection techniques are not appropriate. Whilst relatively safe for the majority of the colon, EFTR for polyps at the appendiceal orifice (AO) results in appendicitis in up to 17% of patients. This case report presents a patient who developed early appendicitis, and a subsequent ruptured appendiceal mucocele following EFTR. Methods A 67 year-old patient was found to have an appendiceal orifice sessile serrated lesion and underwent an EFTR procedure using an over-the-scope-clip (OTSC). The patient developed immediate appendicitis with appendiceal dilation and reactive ileus. This was managed successfully with antibiotics. Two years later, the patient re-presented with another episode of appendicitis with imaging demonstrating an appendiceal perforation. After a course of conservative management, an elective laparotomy was performed which for a dilated, perforated appendiceal with localised mucin. She made a good recovery. Results The final histology confirmed a low grade appendiceal mucinous neoplasm with acellular mucin present at the appendiceal serosal surface, within the pelvis and with desmoplasis to the sigmoid colon. It is likely that the OTSC led to obstruction of the appendiceal lumen and an appendiceal mucocoele. Conclusion EFTR with OTSC should be considered carefully for AO polyps. The risk of appendicitis and upstaging neoplasia may outweigh the benefits with alternative treatment being caecectomy. These lesions should be managed jointly with colorectal surgeons with risks and benefits of alternative treatment options discussed with patients.