Bleeding Disorders and Coagulopathies

Question 1

How does heparin (unfractionated) differ in action to LMWHs (e.g. enoxaparin)

Answer 1

• Both potentiate the action of antithrombin-III
• Heparin potentiates its action globally
• LMWHs potentiate its action on IIa (thrombin) only

Question 2

What are important questions to ask someone with a suspected bleeding disorder?

Answer 2

• Key questions
  
  • Age of onset
  • Spontaneity and frequency
  • Site
  • FHx
  • Medicinal hx
  • Therapy and response
• Always consider acquired causes of bleeding over genetic ones as they are far more common

Question 3

What are the main differences between platelet disorders and coagulation disorders on examination?

Answer 3

• Platelet
  
  • Petechiae (1-2mm, small, flat, non-blanching)
  • Small/multiple ecchymoses (>1cm)
  • Haematomas rare
  • Late bleeding rare
• Coagulation
  
  • Petechiae rare
  • Ecchymoses large and solitary
  • Haematomas more common
  • Late bleeds more common
  • More likely to have a FHx

Question 4

What tests might you commonly order for a patient suspected of a coagulation disorder?

Answer 4

• Platelet count
• APTT
• INR
• TT
• Mixed studies

Question 5

What do serum mixing studies involve? What are they used for?

Answer 5

• Mixing of patient blood with pooled serum.
• Will correct APTT/PT if due to factor deficiency, but not inhibitor abnormalities

Question 6

What does von Willebrand factor normally do?

Answer 6

• Mediates platelet adhesion at injury site and stabilised circulating factor VIII (coagulation initiator)
• Levels are related to degree of ABO glycosylation

Question 7

How might you manage someone with von Willebrand disease?

Answer 7

• Desmopressin - stimulates vW factor release from stores but care with ADH actions (hyponatraemia)
• Replacement of missing factors
• Tranexamic acid

Question 8

What is the abnormality in haemophilia A? How might it be treated?

Answer 8

• Factor VIII deficiency (coagulation initiator)
• FVIII replacement, tranexamic acid, topical thrombin

Question 9

What is Glanzmann’s thrombasthenia?

Answer 9

• GPIIb/IIIa deficiency - a platelet disorder

Question 10

How might you assess for platelet disorders?

Answer 10

• Aggregation studies
• PFA (platelet function analysis)