Risk Factors for Postoperative Bleeding After Cardiac Surgery Under Cardiopulmonary Bypass

Abstract Background: Postoperative bleeding remains a frequent complication after cardiac surgery under cardiopulmonary bypass (CPB), contributing to transfusion requirements, re-exploration, and adverse outcomes. Objective: To identify risk factors associated with postoperative bleeding following cardiac surgery under CPB using the Universal Definition of Perioperative Bleeding (UDPB). Methods: We conducted a retrospective analytical study including adult patients who underwent cardiac surgery under CPB between January 2021 and December 2022. Postoperative bleeding was classified according to UDPB. Patients were compared according to bleeding severity. Multivariate logistic regression was used to identify independent predictors. Results: Clinically significant bleeding (UDPB ≥ class I) occurred in 22.5% of patients, including 18.1% mild-to-moderate and 4.6% severe-to-massive bleeding. Lower body weight and longer operative duration independently predicted UDPB ≥ I bleeding. Severe bleeding was independently associated with higher EuroSCORE II and prolonged CPB duration. Patients with significant bleeding had lower postoperative arterial pressures, greater anemia, increased transfusion exposure, and higher rates of surgical re-exploration. Thirty-day mortality was numerically higher among patients with significant bleeding. Conclusion: Postoperative bleeding after cardiac surgery under CPB is multifactorial. Low body weight, operative complexity, and prolonged CPB are key predictors of bleeding severity. Early risk stratification and optimized perioperative blood management are essential to improve outcomes.