What is the pathophysiology of platelet disorders?

Updated: Nov 30, 2019
  • Author: Perumal Thiagarajan, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Platelet disorders lead to defects in primary hemostasis and produce signs and symptoms different from coagulation factor deficiencies (disorders of secondary hemostasis). The body's reaction to vessel wall injury is rapid adhesion of platelets to the subendothelium. The initial hemostatic plug, composed primarily of platelets, is stabilized further by a fibrin mesh generated in secondary hemostasis. The arrest of bleeding in a superficial wound, such as the bleeding time wound, almost exclusively results from the primary hemostatic plug.

Hence, primary hemostatic disorders are characterized by prolonged bleeding time, and the characteristic physical examination findings are petechiae and purpura. In comparison, defects in secondary hemostasis result in delayed deep bleeding (eg, into muscles and joints) and the characteristic physical examination finding is hemarthrosis. Hemarthrosis and muscle hematomas are not present in primary hemostatic disorders.

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