Venous thromboembolism in pregnancy
From IDWiki
Etiology
Pathophysiology
- Compression of left iliac vein by gravid uterus
- Most common site is left leg (80%), proximal veins (71%), iliac/femoral veins (64%)
Differential Diagnosis
Epidemiology
- Most commonly in post-partum period (up to 6 weeks)
Risk Factors
- Age >35 years
- Obesity
- Prior DVT
- Family history
- Sickle cell disease
- Thrombophilia
- In vitro fertility (IVF) treatments
- Preeclampsia
- Hyperemesis gravidarum
- C-section, especially as emergency
Clinical Manifestations
- LEFT clinical prediction tool has a negative predictive value of 100% if all factors are absent
- Left leg
- Edema ≥2cm calf circmference difference
- First trimester presentation
Investigations
- Doppler ultrasound of the extremities is the best initial test
- Serial ultrasound (three over 6-8 days) has a better negative predictive value
- If ultrasound negative but DVT suspicion is high, need iliac vessel imaging
- If ultrasound negative but PE suspicion is high
- Chest X-ray, followed by perfusion scan (without ventilation scan)
- D-dimer not as useful
- Increase as pregnancy progresses (only 1% normal D-dimer in third trimester)
- Bloodwork
- Only do thrombophilia screen if a significant family history or clot is at an unusual site
Approach to Diagnosis
Management
- Anticoagulation
- If attempting to get pregnant: warfarin, then switch to LMWH when pregnant
- In pregnancy: UFH or LMWH (not warfarin or DOACs)
- Daily dosing may be equivalent to twice daily dosing in pregnancy
- While breastfeeding: UFH, LMWH, or warfarin (not DOACs)
- Duration is 3 months including 6 weeks postpartum interval (which is highest risk period)
- Only consider an IVC filter if they have an absolute contraindication to anticoagulation
Prognosis
- High morbidity and mortality
- Represents about 15% of maternal mortality
