Thromboelastography and Clot Strength

Understanding Clot Strength

Maximum Amplitude (MA) represents the maximum strength of the clot and primarily reflects platelet function and fibrinogen concentration, with normal MA values typically ranging from 50-70 mm, indicating significant clot strength impairment when values are <50 mm 1, 2
Decreased MA suggests thrombocytopenia, platelet dysfunction, or fibrinogen deficiency, which can be associated with increased bleeding risk and higher transfusion requirements 1, 2

Fibrinogen contributes approximately 30-45% to overall clot strength (MA), while platelets contribute 55-70% 3

Use functional fibrinogen TEG to differentiate between fibrinogen and platelet contributions to the low MA 2
If functional fibrinogen TEG is unavailable, check conventional laboratory tests including platelet count and fibrinogen level to guide therapy 2

If fibrinogen level <1.5-2.0 g/L or functional fibrinogen TEG shows decreased contribution, administer fibrinogen concentrate (first choice) at 25-50 mg/kg, with a target fibrinogen level of at least 1.5-2.0 g/L in bleeding patients 2
If platelet count <50,000/mm³ or there is evidence of platelet dysfunction, administer platelet transfusion (1 adult dose), with a target platelet count >50,000/mm³ for most bleeding scenarios 2

Repeat TEG 15-30 minutes after intervention to assess response, with a target MA normalization (typically >50 mm) 2

Standard TEG is insensitive to antiplatelet agents and cannot reliably detect platelet dysfunction, and anemia can paradoxically show hypercoagulable TEG results due to decreased blood viscosity, potentially masking coagulopathy 1, 2
TEG shows high coefficients of variance (7.1-39.9% for TEG parameters), so results should be interpreted with caution and in clinical context, and results vary between devices and are not interchangeable between TEG and ROTEM systems 1

In pregnancy, baseline MA values are elevated due to physiologic hypercoagulability, so pregnancy-specific reference ranges must be used, and low MA (≤54.2 mm) in pregnancy is associated with significantly high odds ratio of obstetric complications 3, 4