Thromboelastogrpahy (TEG, ROTEM) is a method for testing of fibrin rigidity following blood coagulation. We standardized assessment in citrated plasma.
Various activators in selected concentrations (only recalcification, ellagic acid, silica and tissue factor), coagulation inhibitors or thrombolytics can be added and tested in different types of plasma including that of hemophilia patients.
What is seen is the increase in fibrin rigidity after the clot gel has been formed. Contributions to the rate of rigidity evolution and final rigidity are from coagulation potency (and its inhibitors), fibrinogen concentration and factor XIII activation. Clear dose dependence in plasma can be shown for fibrinogen concentration as depicted on example data. The test is also very sensitive for low tissue factor levels, which can be assayed by recalcification when factor XIa in the sample is neutralized.
Figure: Evolution of rigidity (mm) in time for mixtures of pooled normal plasma and fibrinogen-depleted plasma, reaching various final fibrinogen concentrations between 0.7 and 2.55 mg/mL. Factor XIII subunit a is kept at 100% of pooled plasma by addition of factor XIIIa.