Third space endoscopy pulmonary complications and chylothorax post peroral endoscopic myotomy.

Third-space endoscopy (TSE) has emerged as an effective treatment modality for various gastrointestinal motility diseases and gastrointestinal tumors. TSE is based on the concept of working in the submucosa using a mucosal flap valve technique, which is the underlying premise for all TSE procedures; thus, some complications are shared across the spectrum of TSE procedures. Despite the high safety profiles of most TSE procedures, studies have reported various adverse events, including insufflation-related complications, bleeding, perforation, and infection. Although the occurrence rate of those complications is not very high, they sometimes result in critical conditions. No reports of chylous effusion following TSE procedures, particularly per-oral endoscopic myotomy, have been documented previously. We are presenting the first reported case of chylous pleural effusion after per-oral endoscopic myotomy. Additionally, we aim to present a comprehensive overview, discuss the existing data, and provide insights into pulmonary post-endoscopic complications in light of recent advancements in endoscopic procedures, especially TSE.