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The ristocetin-induced platelet aggregation (RIPA) is an ex vivo assay for live platelet function. It measures platelet aggregation with the help of von Willebrand factor (vWF) and exogenous antibiotic ristocetin added in a graded fashion. [ 1 ]
The test is then started, and platelet aggregation is recorded at approximately 0.5 second intervals for six minutes. Three parameters are calculated: aggregation, velocity and area under the curve (AUC). Aggregation (in AU) is the maximum height of the aggregation curve, and velocity (in AU/min) is the maximum slope of the curve.
The PFA-100 (Platelet Function Assay [1] or Platelet Function Analyser [2]) is a platelet function analyser that aspirates blood in vitro from a blood specimen into disposable test cartridges through a microscopic aperture cut into a biologically active membrane at the end of a capillary.
Thromboelastography (TEG) is a method of testing the efficiency of blood coagulation.It is a test mainly used in surgery and anesthesiology, although increasingly used in resuscitations in emergency departments, intensive care units, and labor and delivery suites.
Platelet aggregation plays a critical role in the genesis of a resulting thrombus. Adhesion should remain local, but platelet aggregation must grow exponentially to form a platelet thrombus and prevent blood loss. Platelet aggregation factors are the regulators that enhance the adhesion and stimulate the platelets to secrete its granules.
Bleeding time is a medical test done to assess the function of a person's platelets. It involves making a patient bleed, then timing how long it takes for them to stop bleeding using a stopwatch or other suitable devices. The term template bleeding time is used when the test is performed to standardized parameters.
Light transmission aggregometry is widely accepted as the gold standard diagnostic tool for assessing platelet function, and a result of absent aggregation with any agonist except ristocetin is highly specific for Glanzmann's thrombasthenia. [9] Following is a table comparing its result with other platelet aggregation disorders:
Exposure of blood to the subendothelial space initiates two processes: changes in platelets, and the exposure of subendothelial platelet tissue factor to coagulation factor VII, which ultimately leads to cross-linked fibrin formation. Platelets immediately form a plug at the site of injury; this is called primary hemostasis.