Endoscopic reversal of Roux-en-Y gastric bypass using lumen-apposing metal stent for the treatment of excessive weight loss and hyperammonemic encephalopathy.

Background and Aims: Hyperammonemic encephalopathy is a rare but potentially life-threatening adverse event following Roux-en-Y gastric bypass (RYGB), typically associated with severe weight loss, sarcopenia, and small-intestinal bacterial overgrowth. This case illustrates the use of endoscopic reversal as a minimally invasive alternative to surgical intervention in a high-risk patient. Methods: We describe a 62-year-old woman with a history of RYGB who presented with progressive neurologic symptoms, elevated serum ammonia levels, and evidence of sarcopenia. After partial response to lactulose and rifaximin, she underwent EUS-guided gastrogastrostomy with placement of a 20-mm lumen-apposing metal stent (LAMS) to restore foregut continuity. Results: The patient demonstrated rapid clinical improvement following the procedure, with a decrease in ammonia levels, resolution of encephalopathy, and progressive weight gain. Follow-up imaging confirmed a patent gastrogastric fistula. The stent was later removed without adverse events, and the patient remained asymptomatic with sustained clinical benefit at 2 months. Conclusions: Endoscopic reversal using EUS-guided LAMS placement may represent a safe and effective option for managing post-RYGB hyperammonemic encephalopathy in patients who are poor surgical candidates. This approach offers a minimally invasive strategy for addressing complex postbariatric metabolic adverse events.