PurposeMarginal ulceration (MU) following Roux-en-Y gastric bypass (RYGB) is an established complication, with early MU (within 30-days of operation) being less understood compared to its late counterpart. This study aims to identify risk factors for early MU in patients undergoing primary RYGB. MethodsUtilizing data from the Metabolic and Bariatric Surgery Accreditation Quality Improvement Project (MBSAQIP 2015-2021), 1,346,468 records were evaluated. After exclusions for revisions, conversions, pediatric cases, nonbinary gender, missing body mass index (BMI) data, and missing operative time; 291,625 cases of primary RYGB were included for full analysis and rare events modeling of early MU. ResultsThe prevalence of early MU was .29% (n = 850). Higher rates of early MU were associated with BMI, race, history of diabetes mellitus (DM), prior thrombotic complications (deep vein thrombosis (DVT) and pulmonary embolism (PE)), prior percutaneous cardiac intervention (PTC), immunosuppressive therapy, and anticoagulation status. Additionally, procedural aspects like the nonspecialization of the surgeon and longer operative times also correlated with higher early MU rates. Rare-events regression modeling noted significant associations of early MU with younger age, diabetes requiring insulin, history of PTC, DVT, immunosuppressive therapy, and anticoagulation status. ConclusionEarly MU remains a relatively rare complication. The lower than previously reported occurrence suggests possible improvements in both patient preparation and surgical technique. The identification of relevant risk factors enables better perioperative and intraoperative management of patients at risk of developing early MU.