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Bleeding disorders: Clinical
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Von Willebrand Disease
Bleeding disorders are classified into problems with primary hemostasis - which is formation of the weak platelet plug, and problems with secondary hemostasis - which is making a strong fibrin clot through activation of the intrinsic, extrinsic and common coagulation pathways.
The first clue in distinguishing between primary and secondary hemostasis is the clinical presentation.
Primary hemostatic problems usually cause petechiae - which are pinpoint superficial skin bleeds, anterior epistaxis - which are usually mild nosebleeds, immediate bleeding after surgical procedures, like tooth extraction, or bleeding from mucosal surfaces, like gingival, gastrointestinal, or vaginal bleeding.
Primary hemostatic problems can be further subdivided into two groups.
The first is a decrease in platelet number, thrombocytopenia - which may be caused by decreased production, increased destruction, or sequestration.
The second is a decrease in platelet function, like in von Willebrand disease, Bernard-Soulier disease, Glanzmann thrombasthenia, uremic platelet dysfunction, and as a result of medications like aspirin, non-steroidal anti-inflammatory drugs or NSAIDs, and clopidogrel.
Patients with primary hemostatic problems often have a prolonged bleeding time, which involves mildly pricking the patient, and then timing how long it takes for them to stop bleeding - normally, this occurs within two to five minutes.
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