Three processes that stop bleeding?
- vasoconstriction
- platelet aggregation
- coagulation cascade
Vascular and platelet causes
VASCULAR DEFECTS Inherited - Connective tissue diseases Acquired - Infection = meningococcal, measles - Henoch-schoenlein purpura (IgA vasculitis)
PLATELET DISORDER Decreased production - Viral infection - Drugs + Radiotherapy - Bone Marrow failure = aplastic and megaloblastic anaemia, marrow infiltration eg. leukaemia or myeloma
Increased Destruction
- Autoimmune = ITP, SLE
- Non-immune = DIC, Thrombotic thrombocytpoenic purprura (TTP), Sequestration in hypersplenism
Poorly functioning Platelets
- Myeloproliferative disease
- NSAIDs
- elevated urea
Coagulation disorders
INHERITED Haemophilia - X linked, mainly affecting men - type A = F8 deficiency, Type B = F9 deficiency - treat by replacing missing factor
Von Willebrand’s Disease
- VWF brings platelets together and causes binding with each other and with endothelial wall damage
- give VWF rich factor 8 for surgery etc
ACQUIRED
Anticoagulants
- Warfarin, Rivaroxaban, Dabigatran
Vitamin K deficiency
Liver Disease
- decreased production of all factors except 8
DIC
- widespread activation of coagulation causing thrombus, followed by bleeding/bruising as clotting factors are used up
Massive blood loss
- Loss of factors and dilution of remaining factors with fluids
Investigations necessary
- Platelet count
- Megakaryocytes in marrow
- low = decreased production
- high = increased destruction - Anti-platelet AB
- APTT
- factors 8,9,11,12 are only assessed using APTT
- correctable = factor deficiency, not = inhibitor eg. SLE - PR
- 2,5,7,10, fibrinogen, prothrombin = extrinsic and common
- If PR high and APTT normal then must be factor 7 - Thrombin Clotting Time (TCT)
- Fibrinogen deficiency
- Thrombin inhibitor (eg. heparin and dabigatran) - Factor Assays
Magegement:
Control any bleeding and eliminate the inhibitor
- reverse and stop Anti-coags
- give steroids and immunosuppresives in acute
avoid giving blood/plasma but give FFP if needed
- educate pts on increased bleeding risk
