Treatment of Emboli During Pregnancy
Low-molecular-weight heparin (LMWH) is the treatment of choice for pulmonary embolism in pregnancy, administered as therapeutic fixed doses based on early pregnancy weight throughout the entire pregnancy, with thrombolysis or surgical embolectomy reserved exclusively for life-threatening, high-risk PE with hemodynamic instability. 1, 2
Types of Emboli in Pregnancy
Pulmonary Embolism (PE)
- Most common embolic complication requiring anticoagulation therapy 1
- Associated with approximately 10.5% of maternal deaths in the United States 3
Amniotic Fluid Embolism (AFE)
- Rare but catastrophic condition occurring during pregnancy or shortly after delivery 1
- Remains one of the leading causes of direct maternal death in high-income countries with a case fatality rate of 13-19% 1
- Incidence approximately 27 per 100,000 maternities 1
Diagnostic Approach for Pulmonary Embolism
Initial Assessment
- Formal diagnostic assessment with validated methods is mandatory if PE is suspected during pregnancy or postpartum (Class I recommendation) 1
- D-dimer measurement and clinical prediction rules should be considered to rule out PE (Class IIa recommendation) 1
Imaging Algorithm
- Start with chest radiograph as the first radiation-associated procedure in all cases 1, 4
- If DVT symptoms present: Perform bilateral venous compression ultrasonography first to avoid unnecessary radiation 1, 4
- If chest X-ray is normal: Perfusion scintigraphy (V/Q scan) is preferred over CTPA 4
- If chest X-ray is abnormal: CTPA should be considered as first-line 1
Radiation Exposure Considerations
- Fetal radiation exposure is minimal with both modalities: V/Q scan (0.02-0.60 mGy) vs CTPA (0.05-0.5 mGy) 4
- Maternal breast radiation is significantly higher with CTPA (3-10 mGy) compared to V/Q scan (0.16-1.2 mGy) 4
Treatment of Pulmonary Embolism in Pregnancy
Standard Anticoagulation (Non-High-Risk PE)
Primary Treatment:
- LMWH is the anticoagulant of choice administered as therapeutic fixed doses based on early pregnancy weight 1, 2
- Continue LMWH throughout the entire pregnancy 2
- NOACs (including apixaban) are explicitly contraindicated during pregnancy and lactation 2
- Unfractionated heparin (UFH) may be considered as an alternative, particularly when rapid reversal is needed 2
Duration:
- Continue anticoagulation for at least 6 weeks postpartum with a minimum overall treatment duration of 3 months 1, 2
- After delivery, heparin may be replaced by vitamin K antagonists (warfarin) 1, 2
- Both LMWH and warfarin can be given to breastfeeding mothers 1
High-Risk PE (Hemodynamically Unstable)
Immediate Management:
- Initiate intravenous unfractionated heparin without delay including weight-adjusted bolus for high clinical probability or hemodynamic instability 2
- Typically, UFH is used in the acute treatment of high-risk PE 1
Advanced Interventions:
- Thrombolysis or surgical embolectomy should be considered for pregnant women with high-risk PE 1
- Thrombolytic treatment should NOT be used peri-partum except in life-threatening PE settings 1
Critical Bleeding Risk Data:
- Following thrombolysis, major bleeding occurred in 18% during pregnancy and 58% in the postpartum period 1
- Fetal deaths occurred in 12% following thrombolysis and 20% following thrombectomy 1
- Maternal survival rates were 94% following thrombolysis and 86% following surgical thrombectomy 1
Alternative Interventions:
- Catheter-directed embolectomy can be considered as initial treatment for hemodynamically unstable gestational PE, potentially bypassing hemorrhagic complications of systemic thrombolysis 3
Peripartum Anticoagulation Management
Labor and Delivery Planning
Timing Considerations:
- Discontinue LMWH at onset of regular uterine contractions 2
- For high-risk situations (recent PE), convert LMWH to UFH infusion ≥36 hours prior to anticipated delivery 1, 2
- Stop UFH infusion 4-6 hours prior to anticipated delivery 1, 2
Regional Anesthesia Safety:
- Do NOT insert spinal or epidural needle unless ≥24 hours have elapsed since last therapeutic LMWH dose 1, 2
- Activated partial thromboplastin time should be normal (not prolonged) prior to regional anesthesia 1
- LMWH should not be given for ≥4 hours after epidural catheter removal 1, 2
Postpartum Reinitiation
- Timing depends on mode of delivery and thrombotic vs. bleeding risk assessment by multidisciplinary team 1
- Consider interim prophylactic LMWH dose post-operatively (after cesarean section), once ≥4 hours have elapsed since epidural catheter removal 1
- Allow interval of ≥8-12 hours between prophylactic and next therapeutic dose 1
Amniotic Fluid Embolism (AFE)
Clinical Presentation
- Characterized by unexplained sudden cardiovascular or respiratory deterioration, often accompanied by disseminated intravascular coagulation 1
- Common presenting symptoms include dyspnea, nonreassuring fetal status, hypotension, seizures, and DIC 5
- Diagnosis is primarily clinical and one of exclusion 1
Risk Factors
- Pre-existing cardiac, cerebrovascular, and renal disorders 1
- Placenta previa, polyhydramnios, stillbirth, chorioamnionitis 1
- Hypertensive disorders, instrumental delivery, and cesarean section 1
Management
- Management is entirely supportive with aggressive life support 1, 5
- Provide high-quality cardiopulmonary resuscitation as initial immediate response 6
- Perform transthoracic or transesophageal echocardiography as soon as possible to identify right ventricular failure 6
- If right ventricular failure identified, initiate inotropic agents and pulmonary vasodilators 6
- Blood pressure support with vasopressors is preferred over fluid infusion in severe right ventricular compromise 6
- Manage coagulopathy with hemostatic resuscitation using 1:1:1 ratio of packed red cells, fresh frozen plasma, and platelets 6
- Maintain serum fibrinogen >150-200 mg/dL with cryoprecipitate as needed 6
- Consider venoarterial extracorporeal membrane oxygenation for prolonged CPR or severe ventricular dysfunction refractory to medical management 6
Multidisciplinary Team Approach
Essential Collaboration:
- A multidisciplinary pregnancy heart team should collaborate in planning ante-, peri-, and postpartum care pathways 1
- Team members should have expertise in PE management during pregnancy and postpartum period 1
- Close collaboration between obstetrician, anesthesiologist, and attending physician is mandatory 1, 2
- Jointly agreed, written care pathways should be available when timelines permit 1
Critical Pitfalls to Avoid
- Never use NOACs during pregnancy - they are explicitly contraindicated 2
- Avoid thrombolysis peri-partum unless truly life-threatening PE with hemodynamic collapse 1
- Do not perform regional anesthesia within 24 hours of therapeutic LMWH dose 1, 2
- Avoid overdiagnosis of PE - has lifelong implications including bleeding risk during delivery, contraindications to estrogen contraception, and requirements for thromboprophylaxis in future pregnancies 1, 4
- Monitor platelet counts closely - discontinue enoxaparin if platelet count falls below 100,000/mm³ 7
- Do not delay diagnostic imaging due to pregnancy - radiation exposure is minimal and diagnosis is critical 4, 8