Describe the platelet function analyzer and its limitations.
The platelet function analyzer (PFA-100) is an intriguing test because it is specific for platelet function, the pri-mary disorder in the parturient. The machine simulates the in vivo hemostatic mechanism of platelet function by accelerating citrated whole blood through a 150 μm aper-ture cut in a collagen membrane. The collagen membrane is coated with one of two platelet activators: epinephrine or ADP. The cartridges are named for the platelet activator that coats them, CEPI or CADP, respectively. The time taken for the aperture to close is called the closure time (CT). This machine is commonly used by hematologists as a screening tool for patients who present with unknown coagulopathies and is sensitive for the detection of von Willebrand disease. Initial studies in the parturient have focused on defining the expected CT and have found that it may be more sensitive than the MA from the TEG for patients with thrombocytopenia and preeclampsia.