الفهرس 
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Abstract
The ability to arrest bleeding, whether from a small puncture or a blood vessel, is largely a function of primary hemostasis, the formation of a platelet plug; although other mechanisms are involved as part of the global hemostatic process.
In clinical practice, bleeding time and platelet count are the only tests used to asses platelet functions, but these tests lack sensitivity and specificity.
The Platelet function analyzer (PFA-100) is the Gold Standard device which simulates primary hemostatic capacity by recording the time taken (closure time, CT) for a platelet plug to occlude a 150-μm aperture in a collagen membrane coated with platelet activator (adenosine diphosphate or epinephrine).
Normal pregnancy although shows a hypercoagulable profile , is associated with lower mean platelet count than non-pregnant. Preeclampsia is associated with platelet dysfunction independent of number and this platelet dysfunction is increased with increasing severity of preclampsia.
Although it is proven that regional anesthesia produces dose dependant alteration in the platelet function , these doesnot increases the amount of intraoperative and postoperative blood loss.
Closure time, is increased with increase in the severity of preeclmpsia and is much increased after spinal anesthesia indicating the effect of spinal anesthesia in decreasing platelet function thus, decreasing the incidence of intraoperative thromboembolic events induced by the periooperative stress and the hypercoagulable state of normal pregnancy.