Anticoagulation management in pediatric extracorporeal membrane oxygenation (ECMO) is challenging with multiple laboratory measures utilized across institutions without consensus guidelines. These include partial thromboplastin time (PTT), thromboelastography (TEG), and antifactor Xa (aXa). We aimed to evaluate the consistency of TEG R-time, PTT, and aXa correlation to bivalirudin and heparin dosing. We conducted a single-center restrospective review of pediatric ECMO cases from 2018 to 2020 anticoagulated with bivalirudin or heparin. We collected up to 14 serial simultaneous TEG R-time, PTT, and aXa measurements over a 7 day ECMO course with corresponding bivalirudin or heparin dosing. We analyzed the correlation between bivalirudin, heparin, and the three measurements of anticoagulation. A total of 67 ECMO runs, 32 bivalirudin, and 35 heparin, and more than 1,500 laboratory values, of which >80% simultaneous, were analyzed. When assessing correlations at the individual patient level, there was no consistent correlation between dosing and at least one laboratory parameter in the majority of patients. Furthermore, 44% of the bivalirudin cohort and 37% of the heparin cohort exhibited no correlation with any parameters. There were statistically significant correlations only between bivalirudin and heparin dosing and the sum total of the different laboratory tests. These inconsistencies highlight the importance of multimodality testing of anticoagulation in the management of pediatric ECMO anticoagulation and cannot be relied on in isolation from bedside clinical judgment.