Heritable Bleeding Disorders

Question 1

How does platelet adhesion and activation occur?

Answer 1

Platelets adhere to damaged endothelium and undergo activation. Platelets aggregate into a thrombus

Question 2

What types of bleeding disorders are there?

Answer 2

• Congenital (single defect)
• Acquired (multiple defects)
• Coagulation defects (deep muscular & joint bleeds)
• Platelet/vessel wall (skin & mucosal)

Question 3

What are the primary & secondary formations of a haemostatic plug?

Answer 3

Primary= aggregation (platelets)-> clotting
Secondary= coagulation-> thrombin->fibrin

Question 4

What are the differences between vascular/platelet and coagulation defects?

Answer 4

• V= Petechiae & superficial bleeding, skin & mucous membranes, Spontaneous, bleeding immediate, prolonged, non-recurrent
• C= Deep spreading haematoma, haemarthrosis, retroperitoneal bleeding, prolonged often recurrent

Question 5

Describe von Willebrand disease

Answer 5

• Absent molecule=severe
• Reduced molecule= less severe
• RCoF value below 30
• Stops production of fibrin
• Autosomal dominant
• Males and females
• Variable penetrance
• Blood group O decreased chance
• Treatment: Vaccinate Hepatitis, antifibrinolytics

Question 6

Name some heritable coagulation factor deficiencies

Answer 6

• XII=Autosomal
• XI=Autosomal, rare
• IX=Haemophilia B,X-linked
• VIII=Haemophilia A, X-linked
• VII=Autosomal

Question 7

Describe haemophilia

Answer 7

• X-linked recessive
• Haem A= 1/5000, factor VIII deficiency
• Haem B= 1/30000, factor IX deficiency

Question 8

What are the intrinsic and extrinsic components of blood

Answer 8

E= Ca2+, Factor VII, tissue factor thromboplastin
I= Ca3+, platelet, factor 8,9,11,12, phospholipid

Question 9

What bleeding/coagulation disorders are screened for?

Answer 9

• Thrombocytopenia
• Disorders of platelet function
• Von Willebrand disease
• Factor VIII deficiency
• Vascular disorder
• Disorder of fibrinolysis
• Mild coagulation factor deficiency

Question 10

What is the test used in a coagulation screen and are there any limitations?

Answer 10

• platelet count & bleeding time for platelet function
• Tests prothrombin time, fibrinogen & Activated Partial Thromboplastin Time
• Not specific for cause, some individuals have constituents out of range but are normal, contamination

Question 11

Name some acquired bleeding disorders

Answer 11

• Vit K deficiency
• Disseminated intravascular coagulation
• Immunoglobulin-mediated factor deficiency/factor VIII deficiency

Question 12

What combination of finding will be seen in von Willebrands syndrome?

Answer 12

Prothrombin time unaffected. Bleeding time: prolonged . Platelet count: unaffected.

Question 13

Which diagnostic test is used to measure the intrinsic coagulation pathway?

Answer 13

APTT