Bleeding Disorders Flashcards
Causes of bleeding
Vascular disorders, platelet disorders (thrombocytopenia, defective function), defective coagulation (inherited, acquired)
Pattern of bleeding
Depends on aetiology, Pattern of bleeding with a vascular and platelet cause bleeding into mucous membranes and skin)
Coagulation disorders: bleeding into joints and soft tissues
Vascular bleeding
Problems with vessel wall
Inherited: Hereditary haemorrhagic telangiectasia, Ehlers-Danlos syndrome
Acquired from: scurvy, steroids, senile
Thrombocytopenia
Low platelet count
under 150-400*10^9/l
Symptoms: Epistaxis, GI bleeds, menorrhagia, bruising - start when platelets less than 10
Acquired from: drug related, immune thrombocytopenia, disseminated intravascular coagulation
ITP
immune thrombocytopenia
Treat with steroids or IV immunoglobulins or occasionally splenectomy
Disorders of platelet function
Platelet count - normal to low
Acquired from drugs like aspirin or NSAIDs
Inherited: rare diagnoses
Coagulation disorders
Due to a defect in coagulation cascade
Usually acquired, inherited is rare
Haemophilia
A: deficiency in factor 8
B: deficiency in factor 9v (Christmas disease)
X linked - affects males only
Clinical features of haemophilia
Spontaneous bleeding into joints and muscles
Unexpected post-op bleeding
Chronic debilitating joint disease - recurrent bleeds in joints - results in arthritis
Usually is a family history
Inheritance of haemophilia
Carrier mums have haemophiliac sons
haemophiliac dads pass gene to daughters
Coagulation tests
APTT: Activated partial thromboplastin time - assesses the intrinsic pathway (factors 8, 9, 11, 12)
PT: Prothrombin time (tests factor 2, 5, 7, 10)
TT: Thrombin time
Fibrinogen level
Factor level assay
Bleeding time
Diagnosis of haemophilia
Prolonged APTT
Normal PT
Low factor 8 or 9 levels
Treatments of haemophilia
Historic: Fractionated human plasma
Current: Infusions of factor 8 or 9, prophylactic treatment
Von villebrand disease
Autosomal dominant disease with deficiency of vWF and factor 8 in plasma
vWF: large multimeric protein that carries factor 8 in the blood
vWF also binds platelets to endothelial collagen
Symptoms: mucocutaneous bleeds, nosebleeds, menorrhagia
Test for vWD
Prolonged APTT Normal PT Low vWF level Prolonged bleeding time Defective platelet function
Treatment for vWD
desmopressin, antifibrinolytics and plasma products
Liver disease
Can cause haemophilia
Defects synthesis of clotting proteins
Impaired platelet function and fibrinolysis
Disseminated intravascular coagulation (DIC)
Release of pro-coagulation material into circulation
Causes both bleeding and thrombosis to occur
Causes of this: cancer, severe infection, obstetric disasters
Meningococcal disseminated intravascular coagulation
Prolonged APTT, PT, TT, low fibrinogen, low platelets, raised D-dimers or raised fibrinogen degradation products (FDP)
Latrogenic
Overdose of anticoagulant drugs
Heparin
Treats MIs, PEs, DVTs
Warfarin
Used to treat PEs, DVTs, atrial fibrillation, prosthetic valves
DOACS
Direct novel oral anti-coagulation
Direct thrombin inhibitors: dabigatran, argatroban
Factor 10a inhibitors: rivaroxiban, apixaban
Vitamin K deficiency
Required for gamma-carboxylation of factors 2, 7, 9, 10
Inhibited by warfarin
Deficiency of vit k due to malabsorption of Vit k, bilary obstruction (jaundice), haemorrhagic disease of new-borns
Monitored by PT
Extrinsic - factors 2, 5,7, 10
Monitored by APTT
Intrinsic
Extrinsic and Intrinsic
Both pathways result in thrombin burst that produces a blood clot and haemostasis
