VTE Prophylaxis in Pregnancy (Green Top 2015)
Intro
Maternal deaths from VTE down from 1.56/100,000 to 0.70/100,000 due to prophylaxis
Absolute Risk of VTE
Absolute risk of VTE in general population of non-pregnant women = approx. 1 in 10,000
Absolute risk of VTE in general population of pregnant women = approx. 1 in 1,000
Important to consider when assessing risk factors - e.g. Being heterozygous for the FVL mutation carries a relative risk increase of 3-5 fold —> from 1 in 1,000 to the still small risk of 3-5 in 1,000.
Which women with prior VTE require thrombophilia testing?
Prior to testing, counsel regarding implications for themselves and family
Test for AT deficiency if: FHx of VTE and either AT def known in family or a specific thrombophilia has not been detected in the family.
Test for APL Antibodies if: the prior VTE was unprovoked
Which women without prior VTE require thrombophilia testing?
Consider testing if: the woman has no personal history or RF’s for VTE but has a FHx of an unprovoked or estrogen-provoked VTE in a 1st degree relative when aged <50.
i.e. if it will change the risk score from 0 to 2.
prophylaxis regimens
Previous VTE Alone (Remember to score any additional factors)
Thrombophilia Alone (Remember to score any additional factors)
Risk Scoring for prophylaxis
relevant trials
Intermediate dose vs low dose LMWH in pregnant and post-partum women with history of VTE
>1000 women. 1o Outcome: objectively confirmed VTE
No difference between the two groups
A few notes on VTE Treatment in Pregnancy
(see full GTG 2015 guideline for details)
Diagnosis
Do not check D-dimer
No role for pre-test probability scores as not validated (ie Wells)
If DVT USS normal but clinical suspicion high, re-scan on days 3 and 7
No need to scan for PE if DVT already proven by USS
VQ higher risk of childhood cancer > CTPA.
CTPA higher risk of maternal breast cancer > VQ.
Absolute risks of both are very small
Treatment
LMWH dose should be calculated on booking weight
Consider monitor Anti-Xa if weight <50kg or >90kg
Continue through pregnancy and for 6 weeks postpartum, or for three months – whichever is the longer duration
Delivery
If VTE occurs at term, consider UFH infusion
Stop LMWH at start of labour, or 24 hours prior to a planned delivery,
Neuroaxial anaesthetic should not be performed until 24 hours after last dose of LMWH, and next dose should not be given until 4 hours after the procedure. The catheter should not be removed within 12 hours after the last dose.