The Principles of the Thromboelastography. The viscoelastic properties of the clot are measured. Whole blood is inserted in the cup. A torsion wire suspends a pin immersed in the cup and connects with a mechanical–electrical transducer. The cup rotates through 4°45′ to imitate sluggish venous flow and activate coagulation. The speed and strength of clot formation is measured in various ways (now usually by computer), and depends on the activity of the plasmatic coagulation system, platelet function and fibrinolysis.