Purpose

Postoperative bleeding is a major concern in pediatric cardiac surgery under cardiopulmonary bypass (CPB). The comparative utility of viscoelastic testing and central laboratory assays for predicting bleeding risk remains unclear. This study aimed to (1) compare the predictive value of thromboelastography parameters—maximum amplitude of citrated functional fibrinogen (CFF-MA) and citrated rapid thromboelastography (CRT-MA)—with central laboratory tests (serum fibrinogen and platelet count) for early postoperative bleeding, and (2) identify clinical factors influencing the correlation between CFF-MA and fibrinogen.

Methods

A retrospective analysis was performed on 357 pediatric patients (< 18 years) undergoing congenital heart surgery with CPB at a single pediatric center in Japan between April 2022 and January 2025. Parameters measured after protamine administration included CFF-MA, CRT-MA, serum fibrinogen, and platelet count. Early postoperative bleeding was defined as chest/pericardial drain output > 10% of estimated blood volume within 6 h post-PICU admission. Predictive ability was assessed using receiver operating characteristic (ROC) curve analysis, and clinical factors were evaluated by multivariable linear regression.

Results

CRT-MA and platelet count demonstrated the highest predictive ability for early postoperative bleeding (area under the curve [AUC] 0.74, 95% CI 0.69–0.79). CFF-MA outperformed serum fibrinogen (AUC 0.72 vs. 0.42, p < 0.001). The correlation between CFF-MA and fibrinogen was notably weaker in infants after protamine administration. Only 3.9% of patients had fibrinogen < 150 mg/dL.

Conclusions

CRT-MA and platelet demonstrated relatively high predictive ability for early postoperative bleeding in pediatric cardiac surgery. The predictive value of CFF-MA and fibrinogen may diverge, especially in younger age groups.