Detection of Direct Oral Anticoagulants and Non-Vitamin K Antagonist Oral Anticoagulants

Limitations of Thromboelastography (TEG)

Standard TEG parameters often remain within normal limits despite the presence of DOACs, with studies showing TEG identified coagulopathy in only 50% of patients on dabigatran and even fewer on other anticoagulants 2, 3
TEG performs better at detecting DOACs at peak concentrations but loses sensitivity for detecting residual drug activity, making it unreliable for clinical decision-making about anticoagulant reversal 2

The World Society of Emergency Surgery (WSES) guidelines strongly recommend performing routine coagulation assays including Activated Partial Thromboplastin Time (aPTT), Thromboplastin Time (TT), Prothrombin Time (PT), INR, and anti-Xa levels to assess anticoagulant exposure in trauma settings 1
For dabigatran, the Thrombin Time (TT) is extremely sensitive and a normal TT reliably excludes clinically relevant dabigatran levels 2, 4
For factor Xa inhibitors (rivaroxaban, apixaban, edoxaban), anti-Xa assays calibrated with the drug of interest are the preferred tests for quantitation 4, 5

Conventional coagulation assays identified a greater proportion of coagulopathy for patients on pre-injury anticoagulation therapy compared to TEG 3
aPTT values exceeded the threshold for coagulopathy in 100% of patients on dabigatran, PT-INR in 85% of VKAs patients, and 63% of patients on anti-Xa inhibitors 5

Dabigatran prolongs aPTT in a concentration-dependent but non-linear manner, especially at higher concentrations (≥200 ng/mL) 5, 6
Rivaroxaban prolongs PT in a dose-dependent manner, but this effect varies based on different thromboplastins due to their differing sensitivities 5

For more accurate assessment, specialized tests such as diluted thrombin time (dTT), ecarin clotting time (ECT), and calibrated anti-Xa assays provide better quantification of DOAC levels 1, 4

The American College of Cardiology recommends that for trauma patients or those requiring emergency surgery, conventional coagulation tests remain the recommended first-line approach for detecting anticoagulant effects 1, 4