What is the treatment for emboli during pregnancy?

Treatment of Emboli During Pregnancy

For pulmonary embolism in pregnancy, therapeutic low-molecular-weight heparin (LMWH) based on early pregnancy weight is the treatment of choice throughout the entire pregnancy, with thrombolysis or surgical embolectomy reserved exclusively for life-threatening high-risk PE with hemodynamic instability. 1

Types of Emboli in Pregnancy

Pulmonary Embolism (PE)

The most common thromboembolic complication requiring anticoagulation treatment 2, 3.

Amniotic Fluid Embolism (AFE)

A rare but catastrophic condition characterized by sudden cardiovascular or respiratory collapse, often with disseminated intravascular coagulation, occurring during pregnancy or shortly after delivery 1. AFE has an incidence of approximately 27 per 100,000 maternities with a case fatality rate of 13-19% 1. Management is purely supportive with aggressive life support measures 1, 4.

Diagnostic Approach for Pulmonary Embolism

Formal diagnostic assessment with validated methods is mandatory if PE is suspected during pregnancy or postpartum (Class I recommendation). 1

Diagnostic Algorithm:

• Start with venous compression ultrasonography (CUS) of lower extremities if DVT symptoms are present - a positive result warrants immediate anticoagulation and avoids thoracic imaging 1, 5
• D-dimer measurement should be considered - approximately 50% of women have normal D-dimer at 20 weeks gestation, and a normal result has the same exclusion value as in non-pregnant patients 1, 5
• Chest radiograph should be the first radiation-associated procedure 5, 6
• If chest X-ray is normal, perfusion scintigraphy (V/Q scan) is preferred over CTPA to minimize maternal breast radiation exposure (0.16-1.2 mGy vs. 3-10 mGy) 1, 5
• CTPA should be considered as first-line if chest X-ray is abnormal 1

All imaging modalities deliver fetal radiation well below the 50 mSv safety threshold 1.

Treatment of Pulmonary Embolism

Standard Anticoagulation Therapy

LMWH is the anticoagulant of choice for PE in pregnancy, administered as therapeutic fixed doses based on early pregnancy weight throughout the entire pregnancy. 1, 6

• Weight-adjusted dosing should be used 1, 6
• Anti-Xa monitoring may be considered at extremes of body weight, with renal disease, or when clinically necessary 1, 7
• Neither LMWH nor unfractionated heparin (UFH) cross the placenta or appear in breast milk 1
• NOACs (including apixaban) are explicitly contraindicated during pregnancy and lactation 6
• Vitamin K antagonists (VKAs) are contraindicated during pregnancy - they cross the placenta, cause embryopathy in the first trimester, and can cause fetal/neonatal hemorrhage in the third trimester 1

High-Risk PE with Hemodynamic Instability

For high-risk PE with shock or cardiac arrest, thrombolysis or surgical embolectomy should be considered, with UFH as the preferred acute anticoagulant. 1

Thrombolysis Risks:

• Maternal survival rates of 94% have been reported 1
• Major bleeding occurs in 18% during pregnancy and 58% in the postpartum period 1
• Fetal deaths occur in 12% of cases following thrombolysis 1
• Thrombolytic agents do not cross the placenta, so fetal risks are indirect from placental abruption, premature labor, or maternal bleeding 8
• Thrombolytic treatment should NOT be used peri-partum except in life-threatening PE 1

Catheter-Directed Embolectomy:

Catheter-directed embolectomy may be considered as an alternative to systemic thrombolysis in hemodynamically unstable patients to potentially reduce bleeding complications 9.

Peripartum Management

Labor and Delivery Planning

Strong consideration should be given to planned delivery in collaboration with a multidisciplinary team to avoid spontaneous labor while fully anticoagulated. 1

• For women on therapeutic LMWH, ≥24 hours must elapse since the last dose before spinal or epidural needle insertion (assuming normal renal function) 1, 6
• For high-risk situations (e.g., recent PE), convert LMWH to UFH infusion ≥36 hours prior to delivery 1, 6
• Stop UFH infusion 4-6 hours prior to anticipated delivery and ensure activated partial thromboplastin time is normal before regional anesthesia 1, 6
• Do not administer LMWH for ≥4 hours after epidural catheter removal 1, 6

Postpartum Anticoagulation

• Continue anticoagulation for ≥6 weeks after delivery with a minimum overall treatment duration of 3 months 1, 6
• LMWH may be replaced by VKAs after delivery 1, 6
• Both LMWH and warfarin can be given to breastfeeding mothers; NOACs are not recommended 1, 6

Critical Pitfalls to Avoid

• Delaying diagnostic imaging due to radiation concerns - all modalities are safe for the fetus 1, 5
• Using thrombolysis for intermediate-risk PE - reserve only for life-threatening hemodynamic instability 1, 8
• Administering regional anesthesia within 24 hours of therapeutic LMWH - risk of spinal hematoma 1
• Prescribing NOACs during pregnancy - they are contraindicated 6
• Overdiagnosis of PE - has lifelong implications including bleeding risk during delivery, contraindications to estrogen contraception, and thromboprophylaxis requirements in future pregnancies 1, 5

Multidisciplinary Team Approach

A multidisciplinary pregnancy heart team should collaborate in planning ante-, peri-, and postpartum care pathways, with jointly agreed written care protocols when timelines permit. 1 The team should include obstetricians, anesthesiologists, hematologists, and cardiologists with expertise in PE management during pregnancy 1, 6.