Bleeding Disorders Flashcards
what are the components of the blood haemostasis system ?
plasma coagulation factors, platelets, blood vessel wall
describe how clots form
damage to vessel wall, collagen and tissue factor exposed, VWF binds to collagen, platelets adhere to VWF/collagen, platelets activate, TF and platelets activate clotting factors to make thrombin, thrombin converts fibrinogen to fibrin clot, stable fibrin-platelet clot formed
what are the consequences of failure of haemostasis in the mouth ?
oral mucosa is highly vascular and saliva contains fibrinolytic substances and rich in bacteria.
bleeding - haematoma - infection - wound breakdown
what can go wrong with haemostasis ?
abnormal primary haemostasis - reduced platelet number or function, reduced VWF.
abnormal coagulation pathway - reduced clotting factors
how are patients with abnormal haemostasis identified ?
clinical evaluation - bleeding history, general medical history, drug history.
laboratory evaluation - FBC inc platelet count, clotting screen measuring PT and aPTT, INR
why should laboratory tests of coagulation function be interpreted with caution ?
not all bleeding disorders cause abnormal FBC, PT or aPTT, abnormal FBC, PT or aPTT don’t always mean increased bleeding risk, further specialist investigation is always required
how are bleeding disorders classified ?
heritable disorders - von willebrand disease, haemophilia A (factor VIII deficiency)
acquired disorders - reduced platelet number e.g. leukaemia or AITP, liver disease, kidney disease, anticoagulant or anti platelet drugs
what is von willebrands disease ?
reduced VWF concentration in plasma, inherited disorder, abnormal primary haemostasis
what are the clinical hallmarks of VWD ?
easy bruising and traumatic skin bleeding
what are the treatments used to prevent bleeding in mild VWD ?
DDAVP/desmopressin releases endogenous FVIII/VWF, tranexamic acid reduces clot breakdown
what is immune thrombocytopenia ?
immune mediated destruction of platelets due to autoantibody production, reduced platelet number, idiopathic or secondary to infection, abnormal primary haemostasis
what is a clinical presentation of immune thrombocytopenia ?
skin purpura
what is the treatment for immune thrombocytopenia ?
immunosuppression with steroids or IV immunoglobulin, splenectomy.
tramexemic acid, platelet transfusion in emergencies
how does liver disease cause bleeding problems ?
reduced production of all coagulation factors, low platelets, abnormal coagulation pathway and primary haemostasis
what are the clinical features of bleeding problems associated with liver disease ?
subconjunctival haemorrhage, corneal arcus, jaundice
