Anatomical Alterations and Endoscopic Strategies After Upper Gastrointestinal Surgery.

With the increasing number of upper gastrointestinal (GI) surgeries, the anatomical changes resulting from these procedures have become diverse and complex, presenting significant challenges for endoscopic evaluation and intervention. This review systematically analyzes the representative anatomical alterations following upper GI surgeries, including esophageal, gastric, and bariatric surgeries, and proposes effective endoscopic approaches tailored to each surgical type. In esophageal surgery, strategies for evaluating structural changes, such as conduit reconstruction, anastomotic strictures, and delayed gastric emptying, are reviewed. Anatomical alterations associated with various reconstruction methods (Billroth I, Billroth II, Roux-en-Y, and double-tract reconstruction), including anastomotic strictures, bile reflux, and remnant gastric dilatation, are discussed, along with detailed approaches for endoscopic access and assessment. Additionally, we address the significant increase in bariatric surgeries (sleeve gastrectomy and Roux-en-Y gastric bypass) in South Korea and discuss the endoscopic management of related complications, such as marginal ulcers, strictures, and gastrogastric fistulae. Through this review, we emphasize that a thorough understanding of surgery-specific anatomical characteristics, meticulous pre- and post-operative reviews of medical records and imaging, and adherence to the recently highlighted "3C principles" (confirm anatomy, check perfusion, and control complications) are essential for enhancing the accuracy and safety of endoscopic diagnoses and interventions in patients with surgically altered anatomy.