ROTEM Describes the Entire Hemostatic Process from Clot Formation to Fibrinolysis
ROTEM (Rotational Thromboelastometry) assesses the complete hemostatic process in whole blood, measuring coagulation from initial clot formation through clot propagation and stabilization, to final clot dissolution (fibrinolysis). 1
Comprehensive Assessment of Hemostasis
ROTEM evaluates the viscoelastic properties of blood clotting as a dynamic, real-time process rather than isolated components 2. The technology provides a global assessment that includes:
Primary Components Measured
Clot initiation phase: Measured by clotting time (CT), which reflects the time required for initial fibrin formation and corresponds to the intrinsic or extrinsic coagulation pathways 1
Clot propagation phase: Assessed through clot formation time (CFT) and alpha angle, representing the speed at which the clot develops and strengthens 1
Clot strength: Quantified by maximum clot firmness (MCF), which reflects the combined contributions of platelets and fibrinogen to overall clot stability 1
Fibrinolysis: Measured by clot lysis parameters (CL30, CL60, or maximum lysis), indicating the breakdown of the clot over time 1
Specific Hemostatic Pathways Evaluated
ROTEM uses different reagents to isolate specific aspects of hemostasis 1:
INTEM: Evaluates the intrinsic coagulation pathway using ellagic acid activation 1
EXTEM: Assesses the extrinsic pathway through tissue factor activation 1, 3
FIBTEM: Isolates fibrinogen's contribution to clot formation by inhibiting platelets with cytochalasin D 1, 4
APTEM: Specifically evaluates the fibrinolytic pathway using aprotinin (a fibrinolysis inhibitor) 1
HEPTEM: Detects heparin effects on coagulation using heparinase 1
Clinical Validation
ROTEM has been validated to detect systemic changes in coagulation activation and fibrinolysis in humans 5. The clotting time correlates strongly with prothrombin fragments (F1+2) as markers of coagulation activation (r = -0.83), while maximum lysis correlates excellently with tissue plasminogen activator levels (r = 0.82) 5. In trauma patients, ROTEM parameters show significant correlations with standard coagulation assays: CA15-EXTEM correlates with PT (r = 0.66), CFT-INTEM with aPTT (r = 0.91), and CA10-FIBTEM with fibrinogen levels (r = 0.85) 3.
Key Distinction from Standard Coagulation Tests
Unlike conventional coagulation tests (PT, aPTT, fibrinogen) that measure isolated components of hemostasis in plasma, ROTEM evaluates the entire coagulation process in whole blood, including cellular components and their interactions 1, 2. This provides a more physiologically relevant assessment of hemostatic function at the point of care 6.
Important Limitations
ROTEM cannot assess the contribution of endothelium to coagulation, so it cannot detect von Willebrand disease or disorders affecting endothelial adherence 7. The test is performed at 37°C and cannot assess the effects of hypothermia on coagulation 7. Results show variability between devices and are not interchangeable between ROTEM and TEG systems 7, 4.