Bleeding disorders Flashcards
After injury, what 3 processes halt bleeding?
Vasoconstriction
Gap plugging by platelets
Coagulation cascade
What 3 groups do disorders of haemostasis fall into?
Vascular defects
Platelet defects
Coagulation defects
What pattern of bleeding do coagulation disorders cause?
Delayed bleeding
What pattern of bleeding do vascular and platelet disorders cause?
Prolonged bleeding
Give some congenital examples of vascular defects
Osler-weber-rendu syndrome
Connective tissue disease (Ehlers danlos)
Give some acquired examples of vascular defects
Senile purpura Infection - meningococcal, measles, dengue fever Steroids Scurvy (perifollicular haemorrhages) Henoch-schonlein purpura
Give some examples of platelet disorders caused by decreased marrow production
Aplastic anaemia
Megaloblastic anaemia
Marrow infiltration (leukaemia and melanoma)
Marrow suppression (cytotoxic drugs and radiotherapy)
Give some examples of platelet disorders caused by increased destruction
Immune thrombocytopenia (ITP) SLE CLL Drugs - heparin Virus DIC Thrombotic thrombocytopenia (TTP) HUS Sequestration (in hypersplenism)
Give some platelet disorders caused by poorly functioning platelets
Myeloproliferative disease
NSAIDs
Increased urea
Give some examples of congenital coagulation disorders
Haemophilia
Von Willebrand’s disease
Give some examples of acquired coagulation disorders
Anticoagulants
Liver disease
DIC
Vitamin K defiency
What is haemophilia A a deficiency of?
Factor 8
How is haemophilia A inherited?
X-linked recessive condition, however 30% of cases arise from new mutations
Describe the clinical presentation of haemophilia A
Depends on the severity
Often early in life or after surgery/trauma
Bleeds into joints - arthropathy
Bleeding into muscles - haematomas (increased pressure can lead to nerve palsies and compartment syndrome)
How is haemophilia A diagnosed?
Increased APTT
Decreased factor 8 assay
How is haemophilia A managed?
Minor bleeding - pressure and elevation
Major bleeding - desmopressin - raises factor 8 - raised by 50% may be sufficient
Severe bleeding - recombinant factor 8 to raise the levels by 100%
What must be avoided in haemophilia A?
NSAIDs and IM injections
What is haemophilia B otherwise known as?
Christmas disease
How do you treat haemophilia B
Recombinant factor 9
What is haemophilia B
Factor 9 deficiency
What is acquired haemophilia caused by?
Suddenly appearing autoantibodies to factor 8
What is the clinical presentation of acquired haemophilia?
Big mucosal bleeds in males and females
How is acquired haemophilia diagnosed?
Increased APTT
Increased factor 8 autoantibody
Factor 8 activity <50%
How do you treat acquired haemophilia
Steroids
Describe the bleeding disorder produced from liver disease
Complicated
Decreased synthesis of clotting factors
Decreased absorption of vitamin K
Abnormalities of platelet function
What bleeding disorder does malnutrition lead to?
Decreased vit K
Decreased production of clotting factors 2,7,9,10
How do you treat bleeding due to decreased vit K absorption
Give 10mg IV vitK
In acute haemorrhage give FFP or human prothrombin complex
Describe the process of fibrinolysis
Plasminogen is converted to plasmin by tissue plasminogen activator. Plasmin can then cleave fibrin and other factors. t-PA and plasminogen both bind to fibrin and thus localise the fibrinolysis to the area of the clot
Name some fibrinolytic agents
Streptokinase
Alteplase
Tenecteplase
Reteplase
Describe how streptokinase works
Streptococcal exotoxin that binds and activates plasminogen
What is the risk of fibrinolytic agents?
Haemorrhage
What is the risk of streptokinase?
Anaphylaxis on repeated doses
Describe the pathophysiology of immune thrombocytopenia (ITP)
Caused by antiplatelet autoantibodies
Describe the clinical presentation of immune thrombocytopenia (ITP)
Children - 2 weeks after infection, Sudden, self limiting purpura
It may also be chronic in women - purpura (pressure areas), menorrhagia, epistaxis, bleeding
How is ITP diagnosed?
Increased megakaryocytes seen on marrow
Antiplatelet autoantibodies may be present
How is ITP managed?
No treatment if mild
If symptomatic however or if platelets <20, give prednisolone. IV immunoglobulin may temporality rise platelets for surgery/pregnancy
If relapses - splenectomy or be cell depletion with rituximab
Eltromopag and romiplostim are alternative options for those with refractory disease
What is osler-weber-rendu otherwise known as?
Hereditary haemorrhagic telangiectasia
Describe hereditary haemorrhagic telangiectasia
Autosomal dominant Multiple telangiectasia on skin and mucous membranes Epistaxis Telangiectasias at multiple sites Visceral lesions - AVM First degree family relative with HHT
What is the most common inherited clotting disorder?
Von Willebrand
What does the prothrombin time test?
The extrinsic pathway
Factors 1,2,5,7,10
What causes the prothrombin time to be prolonged?
Warfarin
Vit K deficiency
Liver disease
DIC
What does activated partial thromboplastin time (APTT) test?
The intrinsic pathway
Factors 1,2,5,8,9,10,11,12
What prolongs the APPT?
Heparin treatment
Liver disease
DIC
Haemophilia
What is the thrombin time?
Time taken for thrombin to convert fibrinogen to fibrin
What prolongs the thrombin time
Heparin treatment
DIC
Dysfibrinogenaemia
What are D-dimers?
Fibrin degradation products, released from cross linked fibrin during fibrinolysis
When are D-dimers released?
DIC
VTE/PE
Inflammation - infection/malignancy
What questions should you ask in a pre-op assessment to establish bleeding risk?
Previous history of any excessive bleeding
Drug history - anything which may affect haemostasis
PMH - lupus or liver disease
