Early and Late Complications After Sleeve Gastrectomy and Roux-en-Y Gastric Bypass: A Narrative Review.

This review aimed to provide an updated overview of early and late complications after metabolic and bariatric surgery (MBS), focusing on incidence, mechanisms, diagnosis, and management, particularly for sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), the 2 most commonly performed procedures in Korea. We performed a narrative review, integrating evidence from recent meta-analyses, systematic reviews, large registry studies, and key guidelines or position statements, supplemented by representative Korean data and procedure-specific details. Early complications, including bleeding (SG 0.6-2.5%, RYGB 1-1.5%), leakage (SG ~1%, RYGB ~0.6%), and venous thromboembolism (0.3-2.4%), notably porto-mesenteric vein thrombosis (0.3-1.0%), remain uncommon yet potentially life-threatening. Advances in surgical technique, computed tomography-based evaluation, and thromboprophylaxis have reduced the incidence of early complications. Late complications are more prevalent and chronic, including gastroesophageal reflux disease (23-28%), sleeve stenosis or twist (0.5-3.5%), gastrojejunal anastomotic stricture (~6%), marginal ulcer (6-16%), internal hernia (0.2-9%), gallstone formation (up to 50%); nutritional deficiencies, including iron deficiency anemia (16-24%), vitamin B12, folate, vitamin D, and calcium deficiencies; and dumping syndrome (up to 40%) and post-bariatric hypoglycemia (~34%). MBS is a safe and effective treatment for severe obesity and its associated comorbidities. However, a procedure-specific understanding of complication patterns, risk factors, and stepwise management strategies is essential to minimize morbidity and to achieve long-term success through multidisciplinary care.