Hematology: Thrombelastogram (TEG)

Basics

• Measures the Viscoelastic Properties of Clot Formation in Real Time
• Procedure:
  • A Small Cup of Blood is Activated & Rotates Around a Pin
  • A Clot Forms Around the Pin & Parameters are Measured
• *Does Not Reliably Detect Effects of Commonly Use Anticoagulants
• Increasingly Being Used in Trauma
  • Conventional Tests Take a Long Time (Over 80 Minutes) and are Often Inaccurate by The Time They Result Due to Transfusions & Physiologic Changes
  • Used to Guide Massive Transfusion & Identify Trauma Induced Coagulopathy
  • May Decrease Transfusion Requirements (Controversial Area of Active Study)
  • *See Hemorrhagic Shock & Trauma Resuscitation

Commercial Types

• Thrombelastogram (TEG)
  • *Not “Thromboelastogram” – Common Misspelling
• Rotational Thromboelastography (ROTEM)
  • Similar but Different Nomenclature of Results

Modifications

• Speed – Based on Activating Agents:
  • Standard TEG – Uses Kaolin (A Type of Clay) to Activate Clot
  • RapidTEG – Uses Kaolin & Tissue Factor to Accelerate Reaction
• Heparinase
  • Added Heparinase (Enzyme to Neutralize Heparin)
  • Measures Inhibitory Effects of Heparin
• Functional Fibrinogen
  • Added Cytochalasin D (Alkaloid Produced by Fungus, Inhibits Platelet Activity)
  • New Maximum Amplitude Differentiates Deficiencies in Fibrinogen vs Platelets
• Platelet Mapping
  • Added Adenosine Diphosphate (ADP) & Arachidonic Acid
  • Measures Inhibitory Effects of Antiplatelet Agents (Aspiring/Clopidogrel)