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Many abnormalities of blood coagulation, including those associate with therapy or anticoagulation, are associated with an increased risk of haemorrhage or thrombosis.
1) Congenital coagulation disorders
Haemophilia A and B and von Willebrand 's disease are numerically the most important causes of haemorrhage. Other factor deficiencies such as fibrinogen, prothrombin, factors V, X, XI, and XIII are less common and deficiency of factor XII is clinically unimportant.
There are several qualitative disorders of platelets, including membrane and granule defects, and there are various causes of congenital thrombocytopaenia that are associated with an increased incidence of haemorrhage.
Congenital thrombophilias (proteins C and S and antithrombin) are associated with an increased incidence of thrombosis.
2) Acquired haemorrhagic disorders
Thrombocytopaenia -leukaemia, myelodysplasia, malignant infiltration of the bone marrow, myelofibrosis, megaloblastic anaemia, marrow hypoplasia, disseminated intravascular coagulation, thrombotic thrombocytopaenic purpura/haemolytic uraemic syndrome, massive blood transfusion, hypersplenism, immune thrombocytopaenia and cytotoxic chemotherapy.
Qualitative platelet disorders - uraemia, liver failure, paraproteinaemia, myeloproliferative disorders, drugs (aspirin, non-steroidal anti-inflammatory).
Anticoagulant or fibrinolytic therapy.
Immune (coagulation factor inhibitors).
Vitamin K deficiency
Disseminated intravascular coagulation.
Liver disease
3) Disturbances of coagulation and haemostasis.
Oral contraceptives
Antiphospholipid antibodies (see above)
Thrombocytosis - essential thrombocythaemia and polycythaemia rubra vera.
Disseminated intravascular coagulation
Congenital thrombophilias (see above)