OB_idiopathic_thrombocytopenic_purpura

OB_idiopathic_thrombocytopenic_purpura - Idiopathic...

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Dr Muhammad El Hennawy Ob/gyn specialist Dumyat Specialised Hospital and Rass El Barr Central Hospital www.geocities.com/mmhennawy Idiopathic Thrombocytopenic Purpura ) ITP± During Pregnancy
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Platelet structure and physiology The Normal Platelet are small, disc-shaped cells without a nucleus, normally measuring 1 to 2um in diameter and 0.5 to 1.0 um in thickness with a volume of about 6ul. The mean platelet count in normal children and adults is about 250x109/L, usually ranging from 150 to 400x109/L. Platelets are derived from the cytoplasm of megakaryocytes, primarily located in the bone marrow. Normally, a platelet is released to the bloodstream and circulates for about 10 days before its removal, largely by the spleen. Platelets circulate freely without adhesion to the vessel wall or aggregation with other platelet . If stimulated, platelets become spherical, extend pseudopods, and adhere to vessel walls and to each other. It participates with the blood vessel, coagulation factors, and other platelets in the initiation of hemostasis A phospholipid bilayer lies within a glycoprotein rich outer coat. Glycoproteins (GP’s) have essential roles in platelet  activity, for example GP Ib and GP IIb-IIIa are important in platelet activation. Internally, a platelet contains an open canicular network, through which granule contents are secreted, and a dense  tubular system, in which intracellular calcium is stored. Dense bodies, alpha granules and lysosomal granules are all  visible within the inactive platelet, in addition to glycogen granules and mitochondria. During activation, the platelet  contracts using actin and myosin . Alpha granules contain von Willebrand factor Platelet factor 4 - inhibits anticoagulants )and heparin± )PDGF± promotes fibroblast activity in repairing vessel wall damage Factor V Fibrinogen Fibronectin Dense bodies contain ADP - initiates platelet activation and recruitment Serotonin - vasoconstrictor -
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Platelet formation megakaryocyte formation of demarcation membranes platelets (pro)platelets
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• aplasia • infiltration • ineffective megakaryopoiesis eg. MDS • selective impairment of platelet production Causes of splenomegaly • infection • inflammation • congestion • maligancy • red cell disorders • storage diseases • immune auto-immune (ITP, SLE drugs infections allo-immune • non-immune sepsis DIC, TTP, HUS hypertensive disorders of pregnancy look for splenomegaly bone marrow investigation review meds look for underlying disorders review meds THROMBOCYTOPENIA rule out pseudothrombocytopenia SEQUESTRATION PRODUCTION DESTRUCTION Also Artefactual )false± or pseudothrombocytopenia Clot in the sample.- Platelets clumped. Congenital thrombocytopenia
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This note was uploaded on 12/24/2011 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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OB_idiopathic_thrombocytopenic_purpura - Idiopathic...

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