This document discusses various causes of hemorrhagic diathesis, or increased bleeding tendency. It describes vessel wall abnormalities that can cause less serious bleeding with normal coagulation tests. These include microbial damage, scurvy, drugs, and amyloid infiltration. Thrombocytopenia can also cause bleeding and can result from decreased platelet production or survival. Specific causes mentioned include immune thrombocytopenic purpura in children and adults. Thrombotic microangiopathies like thrombotic thrombocytopenic purpura and hemolytic uremic syndrome involve microthrombi formation and can lead to multiple organ failure.

1. Hemorrhagic DiathesisCauses:Increased fragility of vesselsPlatelet deficiency or dysfunctionDerangement of coagulation

2. Vessel Wall AbnormalitiesCommon but bleeding is LESS SeriousNormal Coagulation test1. Microbial damage to Microvasculature or DIC2. Scurvy – Impaired formation of collagen needed for vessel wall support

3. 3. Drugs – immune complex deposits in vessel wall4. Hemoch-Scheonleinpurpura – unknown systemic hypersensitivity disease involve vessels throughout the body & glomerularmesangium5. Amyloid Infiltration of blood vessels – weakens the wall Vessel Wall Abnormalities

4. R/T THROMBOCYTOPENIADecrease productionAplastic anemiaLeukemiasMegalobalstic anemiaDecrease platelet survivalImmune – mediatedNon-immune – mechanical

5. Sequestration – seen in marked splenomegalyDilutional – blood stored > 24hours has less viable plateletsR/T THROMBOCYTOPENIA

6. Idiopathic Immune Thrombocytopenic Purpura ( Autoimmune )1. AcuteSelf-limited HgicdiseaseResolve w/in 6mos.Children after Viral infxn 2 week later  Sudden petechiae, purpuraRisk for cerebral bleedSevere cases Tx w/ corticosteroids

7. 2. ChronicAdults women < 40y/oAssociated withCollagen Vascular DiseaseCLLHIVRepeated episodes of BleedingTx Steroids. IgG, Splenectomy in severe casesIdiopathic Immune Thrombocytopenic Purpura ( Autoimmune )

9. Deposition of Ig fragments in Amyloidosis

13. Thrombotic MicroangipathiesI. Thrombotic Thrombocytopenic Purpura 1. Fever 2. Thrombocytopenia 3. Microangioapthic hemolytic anemia 4. Transient Neurological damage 5. Renal FailureDeficiency of ADAMTS 13 enzymeResults to accumulation of VHMW vWF promote widesopread platelet Microaggregation

14. II. Hemolytic –Uremic Syndrome 1. MicroangiopathicHemolytic anemia 2. Thrombocytopenia 3. Prominence of renal failure 4. No Neurological damageHx of Enteric infection E. coliRelease of Shiga –like toxin  Absorbed in GIT  Binds and Damage endothelial cells in Glomerulus & other sites  Platelet Activation & AggregationThrombotic Microangipathies

15. Widespread formation of hyaline thrombi in microcircualtionPlatelet consumption & Intravascular thrombiMicroangiopathic hemolytic anemiaMultiple Organ failureActivation of coagualtion cascades is NOT OF PRIMARY IMPORTANCEPT/PTT – usually NormalThrombotic Microangipathies

16. Plasmin Act.Proteolysis of clotting facotrs