Review Note
Last Update: 03/07/2025 03:40 AM
Current Deck: ACG Part 2::Obstetrics
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Commit #296234
SS_OB 1.31 Describe the prevention of venous thromboembolism in the pregnant woman
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Commit #296234VTE is a major cause of direct death in pregnancy and peripartum worldwide.
Incidence of VTE 2 in 1,000 pregnancies, with a mortality of 1.5 per 100,000 pregnancies
⅓ to ½ occur post partum.
Risk Factors :
- Pregnancy itself increase risk by 4-5x
- Virchows triad
- Venous stasis : increased venous capacitance in pregnancy due to hormonal dilation of capacitance veins
- Vascular damage : placenta seperationcauses trauma and initiates, can be exacerbated by
- Hypercoagulability : increased plt turnover, enhanced coagulation and fibrinolysis. Increase in thrombin and factors I (fibrinogen), V, VII, VIII, IX, X, and XII. Decrease in protein C and S
- MATERNAL
- previous VTE, heritable or acquired thrombophilia, advanced maternal age (>35 yrs), BMI>30 kg m−2, parity of ≥3, smoking, extensive varicose veins, and pre-existing medical conditions such as cancer, heart failure or inflammatory bowel disease.
- Mechanical heart valves.
- OBSTETRIC
- multiple pregnancy, current pre-eclampsia, Caesarean section, prolonged labour (>24 h), midcavity or rotational operative delivery, stillbirth, preterm birth or postpartum haemorrhage (blood loss of >1 L or blood loss requiring transfusion).
- TRANSIENT
- Surgical procedure, post partum sterilastion, hyperemeiss, ovarian hyperstimulation sundriome, IVF, bone #, current illness
OUTPATIENT PROPHYLAXIS : studies to support pharmacological prophylaxis are small and often retrospective.
- Consider in patients with a history of a single idiopathic, pregnancy-associated or estrogen-associated VTE,
- history of multiple VTEs, regardless of the cause.
- also considered for some patients with a known thrombophilia
- Those on anticoagulation therapy prior to pregnanacy should have risks discussed and changed to heparin based therapy if indicated
INPATIENT PROPHYLAXIS
- Those considered for outpatient thromboprophylaxis
- Medical or surgical admissions (eg, pneumonia, sepsis, orthopedic injury), those on prolonged bedrest (>3 days), and those with additional or multiple accepted risk factors for VTE during pregnancy (eg, obesity, older maternal age, critical illness, malignancy, ovarian hyperstimulation, multiparity)
ANTICOAGULANT CHOICE
- Heparin :
- Does not cross the placenta.
- LMWHs preferred as easier and low requirement for monitoring
- Lower risk of HIT
- UFH may be favoured close to delivery because or rapid reversibility or those with renal failure.
- Warfarin : generally avoided due to embryopathy in early pregnancy
- Risk of bleeding including ICH later in pregnancy
- Direct oral anticoagulants
- Generally not used due to limited information
Dose of LMWH should be based on booking weight and decreased if CrCl <30ml/min
https://www.bjaed.org/action/showPdf?pii=S2058-5349%2822%2900023-3