Bleeding Disorders

Question 1

What are the main areas of haemostasis affected to cause bleeding disorders?

Answer 1

Primary and secondary haemostasis

Question 2

What is the function of von Willebrand factor?

Answer 2

Acts as glue to allow platelets to stick to collagen

Question 3

What are the causes of failure to form a platelet plug?

Answer 3

Vascular abnormalities, thrombocytopenia, platelet function defects, vWF deficiency

Question 4

What are the causes of vascular abnormalities?

Answer 4

Hereditary

Acquired = Vasculitis (HSP), ageing process (loss of collagen)

Question 5

What are the causes of thrombocytopenia?

Answer 5

Hereditary = rare 
Acquired = reduced production, increased destruction (more common)

Question 6

What tends to cause decreased platelet production?

Answer 6

Marrow problems = tends to cause pancytopenia

Question 7

What tends to cause increased platelet destruction?

Answer 7

Coagulopathy = disseminated intravascular coagulation
Autoimmune = most common cause, immune thrombocytopenic purpura
Hypersplenism

Question 8

What are the causes of platelet functional deficits?

Answer 8

Hereditary = rare 
Acquired = drugs (aspirin, NSAIDs), renal failure

Question 9

What is the most common cause of primary haemostatic failure?

Answer 9

Thrombocytopenia = usually acquired

Question 10

What are the causes of vWF deficiency?

Answer 10

Acquired = uncommon
Hereditary = common (1 in 1000), autosomal dominant, mostly mild

Question 11

Are multiple clotting factor deficiencies usually acquired or hereditary?

Answer 11

Acquired = more likely that a single clotting factor deficiency will be hereditary

Question 12

What are the causes of multiple clotting factor deficiencies?

Answer 12

Liver failure = liver produces all clotting factors
Vitamin K deficiency/warfarin therapy
Complex coagulopathy

Question 13

What clotting factors would be affected by vitamin K deficiency/warfarin therapy?

Answer 13

Factors II, VII, IX and X

Question 14

Where are coagulation factors synthesised?

Answer 14

In hepatocytes of the liver

Question 15

What is the function of vitamin K?

Answer 15

Carries out final carboxylation of factors II, VII, IX and X

Question 16

What are some sources of vitamin K?

Answer 16

Diet = leafy green vegetables

Synthesised in upper bowel by bacteria

Question 17

Where is vitamin K absorbed?

Answer 17

In the upper intestine = requires bile salts

Question 18

What are some causes of vitamin K deficiency?

Answer 18

Dietary insufficiency, malabsorption, obstructive jaundice, vitamin K antagonists, haemorrhagic disease of the newborn

Question 19

What is disseminated intravascular coagulation?

Answer 19

Excessive and inappropriate activation of the haemostatic system

Question 20

What areas of haemostasis are affected by disseminated intravascular coagulation?

Answer 20

Primary and secondary haemostasis plus fibrinolysis

Question 21

What occurs in disseminated intravascular coagulation?

Answer 21

Microvascular thrombus formation = end organ failure
Clotting factor consumption = bruising, purpura, generalised bleeding
High levels of D-dimers

Question 22

What are some causes of disseminated intravascular coagulation?

Answer 22

Sepsis, obstetric emergencies, malignancy, hypovolaemic shock

Question 23

What is the treatment of disseminated intravascular coagulation?

Answer 23

Treat underlying cause and give replacement therapy while waiting for definitive diagnosis = platelet and plasma transfusion, fibrinogen replacement

Question 24

What are haemophilias?

Answer 24

X-linked hereditary disorders = cause abnormally prolonged bleeding that recurs episodically at one or a few sites

Question 25

Why is haemophilia masked in females?

Answer 25

They have two X chromosomes so the healthy one masks the abnormal one = always presents in men as they only have one X chromosome

Question 26

What does haemophilia cause?

Answer 26

Deficiency of factor VIII or IX
Bleeding from medium to large vessels
Bleeding normally occurs into joints = ankles and knees most common sites

Question 27

What are the types of haemophilia?

Answer 27

Haemophilia A = factor VIII deficiency, more common

Haemophilia B = factor IX deficiency

Question 28

What are the classes of haemophilia?

Answer 28

Mild, moderate and severe = severe is most common

Question 29

What areas of haemostasis are affected by haemophilia?

Answer 29

Primary haemostasis not affected but secondary is

Question 30

How are clotting times affected by haemostasis?

Answer 30

Normal prothrombin time

Prolonged activated partial thromboplastin time

Question 31

What are the features of severe haemophilia?

Answer 31

Recurrent haemoarthroses
Recurrent soft tissue bleeds = bruising in toddlers
Prolonged bleeding after surgery or dental extractions

Question 32

How is haemophilia treated?

Answer 32

Self administered IV clotting factor concentrates = prevent abnormal bleeding