Causes of failure of haemostasis Flashcards
Secondary haemostasis failure can be due to individual clotting factor deficiencies and multiple clotting factor deficiencies: What would be the cause of a single clotting factor deficiency?
Haemophilia:
Haemophilia A is a factor VIII deficiency
Haemophilia B is a factor IX deficiency
= no amplification
Haemophilia:
- what pattern of inheritance is it
- what pattern of bleeding does it cause
-X-linked inheritance
- causes bleeding from medium to large sized vessels: mild/moderate/severe depending on blood factor levels
- no abnormalities in primary haemostasis so minor injuries are ok
Haemophilia:
- is the problem in the intrinsic or extrinsic pathway?
- how can this be confirmed with tests?
- intrinsic
- PT time normal
- APTT prolonged
What are the clinical features of haemophilia?
- Recurrent haemarthroses of joints under a lot of pressure
- ankles most likely, then knees, then elbows
- recurrent soft tissue bleeds
- prolonged bleeding dental extractions/surgery/invasive procedures
What is a target joint in haemophilia, why do haemophiliacs often end up needing joint replacements?
Target joint:
-after joint has been bled into = inflammatory response. This causes small delicate vessels to be created and increases the chance of a rebleed.
Once a joint has been rebled into = fibrosis and eventual fusion = lack of movement and muscle wasting leading to requiring a replacement
Secondary haemostasis failure can be due to individual clotting factor deficiencies and multiple clotting factor deficiencies: What would be the different causes of multiple clotting factor deficiency?
vit K deficiency
liver failure
DIC
what are the 5 different causes of vitamin K deficiency?
- poor dietary intake
- malabsorption
- obstructive jaundice (bile salts are needed to absorb vit. K)
- vit K antagonists (warfarin)
- haemorrhagic disease of the newborn (if mother has taken anticonvulsants/antiTB meds or if the baby hasn’t recieved prophylactic vit K injections at birth)
What is DIC?what are the 4 causes of DIC?
Disseminated intravascular coagulation
-excessive and inappropriate activation of haemostatic system, then fibrinolysis is then activated
Causes:
- sepsis esp. meningococcal
- obstetric emergency
- malignancy (more chronic, as tissues break down they release tissue factor)
- hypovolaemic shock (as hypoxia causes tissue damage which releases tissue factor)
What are the clinical features of DIC? What can be the end result of DIC?
Clinical features - clotting factor consumption:
- bruising
- purpura
- generalised bleeding
Microvascular thrombus formation can cause end organ failure
How is DIC treated?
- platelet transfusions
- plasma transfusions
- fibrinogen replacement
Primary haemostatic failure:
-what are the four different general causes of this?
- vWF deficiency
- functional platelet defects
- thrombocytopenia
- vascular problems
Describe the causes of vWF deficiency
Hereditary:
- autosoml dominant
- common
- variable severity: generally mild
Acquired:
- relatively rare
- usually elderly
- assoc with monoclonal gammopathies, lymphoproliferative disorders, and myeloproliferative disorders.
- autoantibodies against vWF
Describe the causes of functional platelet defects
Hereditary - rare
Acquired:
- Drugs (eg Aspirin, non-steroidal anti inflammatory drugs) – most common reason (MORE COMMON THAN ITP)
- Renal failure
Describe the vascular causes that result in failure of primary haemostasis
Hereditary: e.g. marfans/ ehler-danlos syndrome
Acquired
-Vasculitis eg Henoch-Schonlein Purpura
What is henoch-schonlein purpura?
provoked by a viral infection
see purpura
mimics meningitis
self limiting
