Pulmonary Embolism in Pregnancy

Aka: Pulmonary Embolism in Pregnancy

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II. Epidemiology

  1. See Thromboembolic Disease in Pregnancy
  2. Pulmonary Embolism is a leading cause of maternal death
  3. Two thirds of thromboembolic events in pregnancy are DVT (diagnosable by Ultrasound)
  4. Overall risk of Pulmonary Embolism in Pregnancy: 3 in 10,000
  5. Risk of Pulmonary Embolism increases with advancing pregnancy and especially postpartum
    1. First trimester PE Risk: 1 in 50,000
    2. Third trimester PE Risk: 1 in 10,000
    3. Two thirds of pregnancy-related Pulmonary Embolism occur postpartum (esp after Cesarean Section)
    4. Meng (2015) J Matern Fetal Neonatal Med 28(3): 245-53 +PMID:24716782 [PubMed]

III. Findings: Symptoms and signs

  1. See Pulmonary Embolism
  2. Dyspnea
  3. Tachypnea
  4. Tachycardia (esp. above mild Tachycardia often seen in pregnancy)
  5. Chest Pain may be present
  6. Unilateral leg signs of DVT (esp. left leg) in pregnancy may be present
    1. See DVT in Pregnancy

IV. Differential Diagnosis: Dyspnea and Leg Edema in pregnancy

  1. Precautions
    1. Pregnancy-related Dyspnea and edema are common in normal later pregnancy
    2. Maintain a high index of suspicion and exclude serious causes in differential
  2. See Chest Pain Causes
  3. See Dyspnea Causes
  4. See Leg Pain Causes
  5. Hypertensive Disorders of Pregnancy (e.g. Preeclampsia)
  6. Peripartum Cardiomyopathy
  7. Amniotic Fluid Embolism

V. Labs

  1. D-Dimer: Discriminatory value in low risk Pulmonary Embolism
    1. First trimester pregnancy: <500 ng/ml
    2. Second trimester pregnancy: <750 ng/ml
    3. Third trimester pregnancy: <1000 ng/ml
  2. YEARS Score Based Algorithm
    1. Indications for CT Pulmonary Angiogram
      1. No YEARS Score Criteria AND D-Dimer >1000 OR
      2. One YEARS Score Criteria AND D-Dimer >500
  3. References
    1. Chan (2010) J Thromb Haemost 8(5): 1004-11 +PMID:20128870 [PubMed]
    2. Ercan (2014) J Matern Fetal Neonatal Med 25:1-5 +PMID:25060670 [PubMed]
    3. Kovac (2010) Eur J Obstet Gynecol Reprod Biol 148(1): 27-30 +PMID:19804940 [PubMed]

VI. Diagnostics

  1. Arterial Blood Gas
    1. A-a Gradient >20 mmHg
    2. PaO2 <85 mmHg
      1. When >28 weeks, may drop when supine by 15 mmHg
  2. Electrocardiogram (EKG)
    1. See EKG in Pulmonary Embolism

VII. Imaging

  1. See Pulmonary Embolism Diagnosis
  2. Bilateral lower extremity venous Doppler Ultrasound
    1. Start with Ultrasound in most cases
    2. Positive Ultrasound should be treated as presumed Pulmonary Embolism and no CTPA needed
    3. Negative Ultrasound does NOT exclude PE and requires additional testing (see CTPA below)
    4. Proximal DVT is much more common in pregnancy
      1. Iliofemoral DVT accounts for 72% of pregnancy-related DVTs
    5. Left leg DVT accounts for 90% of DVT in Pregnancy
      1. Gravid Uterus puts more pressure on left pelvic veins with secondary Venous Stasis
  3. PE evaluation
    1. See Radiation Exposure in Pregnancy
    2. CT Pulmonary Angiography (CTPA, Spiral CT)
      1. Preferred in pregnancy (prior first-line was perfusion only VQ Scan)
        1. However 2011 ATS guidelines recommended VQ Scan before CT
      2. Fetal Radiation Exposure: 130 uGy (0.13 mGy, range 0.03 to 0.66 mGy, depending on timing in pregnancy)
      3. Contrast dye remains in amniotic fluid for months
    3. Ventilation-Perfusion Scan (V/Q Scan)
      1. Fetal Radiation Exposure: 370 uGy (0.37 mGy)
      2. Perform perfusion (Q) only scan if normal lung history (and negative Chest XRay)
    4. MRI Lung
    5. Pulmonary Angiography

VIII. Evaluation: Suspected Pulmonary Embolism

  1. See Thromboembolic Disease in Pregnancy
  2. Low DVT suspicion: Obtain D-Dimer
    1. D-Dimer negative: PE excluded
    2. D-Dimer positive: Go to high suspicion protocol below
  3. Intermediate or High DVT suspicion: Obtain Spiral CT (or V/Q Scan if CT not available)
    1. Spiral CT normal: PE excluded
    2. Spiral CT positive: Anticoagulation per Pulmonary Embolism protocol
    3. Spiral CT indeterminate: Obtain additional testing
      1. Ventilation-Perfusion Scan (V/Q Scan)
      2. Venous Compression Ultrasound (VCUS)
      3. MRI Lung
      4. Pulmonary Angiography

IX. Management

  1. See Thromboembolic Disease in Pregnancy
  2. See Pulmonary Embolism Management
  3. ABC Management
    1. Oxygen Supplementation
    2. Cardiopulmonary stabilization
  4. Anticoagulation
    1. See Anticoagulation in Thromboembolism
    2. Heparin until delivery
      1. Unfractionated Heparin (weight-based) infusion or
      2. Low Molecular Weight Heparin
        1. Convert to infusion 24 hours before epidural
    3. Avoid Contraindicated agents
      1. Factor Xa Inhibitor (e.g. Rivoroxaban)
      2. Warfarin (do not use in pregnancy)
        1. May be used in Lactation
  5. IVC Filter
    1. Indicated for Pulmonary Embolism within 4 weeks of estimated delivery date
  6. Thrombolysis is absolutely contraindicated (EXCEPT in life threatening, massive PE)
    1. Risk of major bleeding 2.6%
    2. Consider in life-threatening massive Pulmonary Embolism if not near term
    3. Gartman (2013) Obstet Med 6:105-11 [PubMed]

X. Prevention

  1. See DVT in Pregnancy for prophylaxis

XI. References

  1. Bavolek and Herbert in Herbert (2021) EM:Rap 21(2): 4-5
  2. Swaminathan and Kline in Herbert (2016) EM:Rap 16(3): 1-3
  3. Condliffe (2014) Thorax 69(2): 174-80 [PubMed]

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