What is a Thromboelastography (TEG) scan used for?

Thromboelastography (TEG) Scan: Clinical Applications and Utility

Thromboelastography (TEG) is a point-of-care viscoelastic testing method that provides real-time assessment of whole blood coagulation and fibrinolysis, allowing clinicians to evaluate the entire hemostatic process from clot formation through clot dissolution. 1

TEG Parameters and Their Clinical Significance

TEG measures several key parameters that provide comprehensive information about the coagulation process:

• R time (Reaction time): Measures time from test start to initial fibrin formation

  • Prolonged in factor deficiency or anticoagulant effect
  • Shortened in hypercoagulable states 1

• K time (Kinetics): Represents speed of clot formation

  • Prolonged in hypofibrinogenemia or thrombocytopenia
  • Shortened in hypercoagulable states 1

• Alpha angle (α): Reflects fibrinogen function and platelet interaction

  • Decreased in hypofibrinogenemia or platelet dysfunction
  • Increased in hypercoagulability 1

• MA (Maximum Amplitude): Represents platelet function and fibrinogen contribution

  • Decreased in thrombocytopenia, platelet dysfunction, or hypofibrinogenemia
  • Increased in hypercoagulable states 1

• LY30/LY60 (Lysis at 30/60 minutes): Reflects fibrinolytic activity

  • Increased values indicate hyperfibrinolysis 1

Clinical Applications of TEG

1. Trauma and Massive Transfusion

• Guides component therapy based on specific deficiencies
• Identifies hyperfibrinolysis requiring antifibrinolytic therapy
• Helps reduce unnecessary blood product use 1

2. Cardiac Surgery

• Guides hemostatic management during and after cardiopulmonary bypass
• Differentiates surgical from coagulopathic bleeding
• Reduces transfusion requirements 1, 2

3. Liver Disease

• Reveals rebalanced hemostasis despite abnormal conventional tests
• Reduces unnecessary blood product use in cirrhotic patients with nonvariceal bleeding 1

4. Obstetrics

• Detects pregnancy-associated hypercoagulability
• Monitors hemostatic changes in preeclampsia/eclampsia
• Guides transfusion therapy for postpartum hemorrhage
• Evaluates effects of obstetric anesthesia on coagulation 3

5. Anticoagulation Monitoring

• Detects anticoagulant effects of heparin and low molecular weight heparin
• Differentiates heparin effect from coagulopathy using heparinase TEG 3, 1

6. Vascular and Endovascular Surgery

• Predicts presence and stability of carotid plaques
• Analyzes platelet function before carotid stenting
• Compares efficacy of antiplatelet therapy after stent deployment 4

Advantages of TEG Over Conventional Coagulation Tests

• Provides a comprehensive assessment of the entire coagulation process
• Delivers results quickly (within 30 minutes)
• Uses whole blood samples, accounting for cellular components
• Detects hypercoagulable states not identified by conventional tests
• Guides targeted blood component therapy 5, 6

Limitations and Challenges

• High coefficients of variance (7.1% to 39.9%) for TEG parameters
• Limited sensitivity for detecting platelet function disorders or effects of antiplatelet drugs
• Results must be interpreted in device-specific context
• Hemolysis can interfere with results
• Delayed analysis and improper collection technique can affect results 1

Best Practices for TEG Implementation

• Establish institution-specific reference ranges
• Implement rigorous quality control measures
• Ensure adequate training of personnel
• Interpret results in clinical context
• Use specialized TEG tests (heparinase, functional fibrinogen) when appropriate 1

TEG technology continues to evolve, with growing evidence supporting its use across multiple clinical scenarios. While initially developed for surgical applications, its utility has expanded to include medical patients as well, offering a valuable tool for diagnosing coagulopathies and guiding targeted blood product administration 7, 2.