Risk factors for VTE

Question 1

Previous VTE outside pregnancy

Answer 1

• Recurrence rates of 2–11%
• Recurrence is very low if the prior VTE was provoked by a transient major risk factor that is no longer present
• All need post natal prophylaxis

Question 2

Thrombophilia-associated VTE

Answer 2

• Antithrombin deficiency and APS: extra thromboprophylaxis during and post natally
• Others normal thromboprophylaxis
• ## If anti Xa used then 4-hour peak levels of 0.5–1.0 iu/ml aimed for

Question 3

Other types of previous VTE

Answer 3

• Estrogen related/ unprovoked: throughout

- Surgery but no other risk factors: start at 28 weeks

Question 4

Asymptomatic thrombophilia

Answer 4

• Together with other 3 risk factors: thromboprophylaxis throughout
• Together with 2 other risk factors: from 28 weeks
• Together with 1 other risk factor: 10 days postnatally
• No risk factors but fhx of relative under age 50: trombophilia screen