VTE in pregnancy GT37a, b Flashcards
How many DVTs in pregnancy occur on the left?
90%
60 when not pregnant
How many DVTs arise in the ileo-femoral veins?
70%
How many with a clinical diagnosis go on to have a proven DVT?
8%
How many proven DVT patients will have a PE?
5%
How much more likely to develop DVT if previous VTE?
25 times
Recurrence rate 2-11% in pregnancy
What is the advice if there is a strong clinical suspicion but a negative scan?
Repeat 3/7
MRV if still suspicious
Which LFT is affected by tinzaparin?
ALT
How many will have a skin allergy to LMWH within 60 days?
2%
How does LMWH work?
Potentiates antithrombin III which inhibits conversion of X to Xa
What is the advice around delivery for those on antenatal treatment dose LMWH?
IOL when favourable or 40/40 - consider prophylactic dose if unfavourable on day IOL
24 hours from dose before regional anaesthetic
Prophylactic dose 1-2 days following VB and 2-3 days following CS
Protamine if labours within 3 hrs of LMWH dose
How much does CS increase the risk of a PE?
5 times
How much does VQ scan increase the risk of childhood cancer?
1:1000,000 background to 1:280,000
How much does CTPA increase breast cancer risk?
14%
How much does antithrombin deficiency increase risk of VTE?
10 times - 50% of untreated patients will have a VTE
What % of patients with pregnancy related VTE will have an underlying thrombophilia?
50%
How many of general population have factor V leiden deficiency?
What is the risk of VTE in pregnancy?
5%
1:100 (1:1000 when not pregnant)
What is the risk of devloping a VTE in subsequent pregnancies?
10%
How should anti-Xa levels be measured?
A test that does not use exogenous antithrombin, aim for 4 hour peak levels of 0.5-1.0iu/ml
What is the advice for women who are taking warfarin antenatallly and fall pregnant?
Stop and change to LMWH as soon as pregnancy confirmed, ideally within 2/52 of missed period and by 6/40
Which women with prior VTE require thrombophilia testing?
Only if result will influence Rx - antithrombin/APS may alter dose of LMWH
FHx VTE with antithrombin deficiency or thrombophilia not detected
Unprovoked VTE - test for APL antibodies
Consider if no personal hx but FHx of unprovoked/oestrogen dependent VTE in 1st degree relative <50