12.3 Coagulopathies

Question 1

Virchow’s Triad describes the three fundamental factors that cause thrombosis. What are they?

Answer 1

• Hypercoagulability
• Vessel damage
• Circulatory stasis

Question 2

List some causes of hypercoagulability

Answer 2

• Malignancy
• Inflammation
• Dehydration
• Major surgery/trauma

Question 3

Describe factor V Leiden mutation. How does it affect blood clotting? Is it inherited or acquired?

Answer 3

• Inherited
• Factor V is no longer downregulated by C and S proteins
• Prevents downregulation of coagulation cascade, since factor V is not inactivated as easily
• Leads to hypercoagulability

Question 4

List five inherited causes of hypercoagulability

Answer 4

• Factor V Leiden Mutation
• Activated C Protein Resistance
• Protein C Deficiency
• Protein S Deficiency
• Antithrombin deficiency

Question 5

During pregnancy, the body adapts to prevent loss of blood. List some ways in which this can cause hypercoagulability

Answer 5

• Decreased venous blood flow (stasis)
• Increased APC resistance
• Decrease in protein S activity
• Increase in inhibitors of fibrinolysis

Question 6

How does malignancy cause hypercoagulability

Answer 6

• Increased expression of Tissue Factor
• Venous stasis from tumour compression
• Some cancer treatments

Question 7

How does covid cause clotting?

Answer 7

Inflammation*

Question 8

Normal prevalence of coagulopathies

Answer 8

1 in 1000

Question 9

List some risk factors for coagulopathies

Answer 9

• Pregnancy
• Obesity
• Male
• Increased age
• Previous VTE
• Malignancy
• Estrogen HRT

Question 10

Prevalence of coagulopathies in patients with malignancy

Answer 10

Around 25%

Question 11

What is the increase in clotting risk in Factor V Leiden mutation hetero vs homozygous?

Answer 11

Hetero: 8x
Homo: 80x

(Interesting use of anchoring)

Question 12

What kinds of people need to be tested for inherited coagulopathy risk factors? Why do we need to be careful doing this?

Answer 12

Consider testing:
- Spontaneous, unprovoked thrombosis
- Young age thrombosis
- Recurrent pregnancy losses

But be careful: this can make insurance much more expensive

Question 13

What is the gold-standard imaging for DVT diagnosis?

Answer 13

Duplex ultrasound

Question 14

There are two parts to a duplex ultrasound; what are they?

Answer 14

• Vein compressibility (you can’t compress if there is a clot…)
• Doppler waves to detect flow

Question 15

Common presenting symptoms of DVT

Answer 15

Lower limb:
- Erythema
- Unilateral swelling
- Rubor (warmth)

Question 16

For which patients is a D-Dimer a useful blood test? Is it useful for ruling in or ruling out?

Answer 16

• Useful in patients with low-moderate pre-test likelihood of VTE
• Used to rule out