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Abnormalities can develop in any of the components of haemostasis. Disorders of primary haemostasis include vessel defects (i.e. vasculitis), thrombocytopenia (due to decreased production or increased destruction) and abnormalities in platelet function (e.g. congenital defects, disseminated intravascular coagulation). These lead to the occurence of multiple minor bleeds and prolonged bleeding. For example, petechial or ecchymotic haemorrhages may be seen on the skin and mucous membranes, or ocular bleeds may arise. Generally, intact secondary haemostasis prevents major haemorrhage in disorders of primary haemostasis. When secondary haemostasis is abnormal, larger bleeds are frequently seen. Haemothorax, haemoperitoneum, or haemoarthrosis may occur, in addition to subcutaneous and intramuscular haemorrhages. Petechiae and ecchymoses are not usually apparent, as intact primary haemostasis prevents minor capillary bleeding. Examples of secondary haemostatic disorders include clotting factor deficiencies (e.g. hepatic failure, vitamin K deficiency, hereditary disorders) and circulation of substances inhibitory to coagulation (FDPs in disseminated intravascular coagulation, lupus anticoagulant). If fibrinolysis is defective, thrombus formation and infarctions may result. Thrombus formation may be promoted by vascular damage, circulatory stasis or changes in anticoagulants or procoagulants. For example, ATIII may be decreased. This can occur by loss due to glomerular disease or accelerated consumption in disseminated intravascular coagulation or sepsis.

Abnormalities can develop in any of the components of haemostasis. Disorders of primary haemostasis include [[Haemorrhagic_Disease_Pathophysiology#Vascular_Fragility|vessel defects]] (i.e. vasculitis), [[Platelet_Abnormalities#Thrombocytopaenia|thrombocytopenia]] (due to decreased production or increased destruction) and [[Platelet Abnormalities|abnormalities in platelet function]] (e.g. congenital defects). These lead to the occurence of multiple minor bleeds and prolonged bleeding. For example, petechial or ecchymotic haemorrhages may be seen on the skin and mucous membranes, or ocular bleeds may arise. Generally, intact secondary haemostasis prevents major haemorrhage in disorders of primary haemostasis. When secondary haemostasis is abnormal, larger bleeds are frequently seen. Haemothorax, haemoperitoneum, or haemoarthrosis may occur, in addition to subcutaneous and intramuscular haemorrhages. Petechiae and ecchymoses are not usually apparent, as intact primary haemostasis prevents minor capillary bleeding. Examples of secondary haemostatic disorders include clotting factor deficiencies (e.g. hepatic failure, vitamin K deficiency, hereditary disorders) and circulation of substances inhibitory to coagulation (FDPs in disseminated intravascular coagulation, lupus anticoagulant). If fibrinolysis is defective, thrombus formation and infarctions may result. Thrombus formation may be promoted by vascular damage, circulatory stasis or changes in anticoagulants or procoagulants. For example, ATIII may be decreased. This can occur by loss due to glomerular disease or accelerated consumption in disseminated intravascular coagulation or sepsis.

It is therefore important that all aspects of haemostasis can be independantly evaluated. This will help to identify the phase affected and to pinpoint what the abnormality is. There are tests available to assess primary haemostasis, secondary haemostasis and fibrinolysis.

It is therefore important that all aspects of haemostasis can be independantly evaluated. This will help to identify the phase affected and to pinpoint what the abnormality is. There are tests available to assess primary haemostasis, secondary haemostasis and fibrinolysis.