Amniotic Fluid Embolism

Aka: Amniotic Fluid Embolism, Pulmonary Embolism of Amniotic Fluid, Anaphylactoid Syndrome of Pregnancy

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II. Epidemiology

  1. Incidence: 1 in 8000 to 80,000 live births

III. Pathophysiology

  1. Amniotic fluid released into maternal circulation
  2. Amniotic fluid induces anaphylactoid-type immunologic response
  3. Results in transient pulmonary artery spasm
  4. Causes Hypoxia, pulmonary capillary injury and left ventricular injury
  5. Results in Left Ventricular Failure, ARDS, DIC and multi-system failure

IV. Symptoms

  1. Severe, sudden onset Dyspnea

V. Signs

  1. Tachypnea
  2. Hypoxia
  3. Severe shock of rapid onset
  4. Altered Mental Status or encephalopathy
  5. Cyanosis
  6. Hypotension
  7. Cardiopulmonary arrest

VI. Risk Factors

  1. Trauma in Pregnancy
  2. Amniotomy
  3. Strong uterine contractions

VII. Differential Diagnosis

  1. Pregnancy Induced Hypertension
  2. Abruptio Placentae
  3. Uterine Rupture
  4. Aspiration Pneumonia

VIII. Lab

  1. Arterial Blood Gas
  2. Complete Blood Count with Platelets
    1. Thrombocytopenia
  3. Urinalysis
  4. Type and Cross 4-6 units Packed Red Blood Cells
  5. Coagulation studies
    1. D-Dimer
    2. ProTime (PT, INR)
    3. Partial Thromboplastin Time (PTT)
    4. Fibrin split products (Fibrin Degradation Products)
    5. Fibrinogen (low)
    6. Clot Test

IX. Imaging

  1. Chest XRay
    1. Bilateral infiltrates may be seen with progression

X. Diagnostics

  1. Electrocardiogram (EKG)
    1. Sinus Tachycardia
    2. Dysrhythmias

XI. Management

  1. Emergent supportive care
    1. Oxygen Supplementation
    2. Intravenous Access
    3. Endotracheal Intubation
    4. Vasopressors
    5. Fluid Resuscitation
    6. Correct coagulation deficits
  2. Advanced Measures to consider
    1. Venoarterial ECMO
    2. Uterine Artery Embolization
    3. Exchange Transfusion
  3. A-OK Amniotic Fluid Embolism Protocol
    1. Atropine 1 mg IV (vagolytic) AND
    2. Ondansetron 8 mg IV (Serotonin blockade) AND
    3. Ketorolac 30 mg IV (Thromboxane production blockade)
    4. Rezai (2017) Case Rep Obstet Gynecol +PMID: 29430313 [PubMed]
      1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5753013/
  4. Admit to Intensive Care unit
  5. Consultations
    1. Maternal-fetal medicine
    2. Medicine
    3. Neonatology

XII. Monitoring

  1. Check Hemoglobin every 1 hour (keep above 10 mg/dl)
  2. Check Hematocrit every 1 hour (keep above 30)
  3. Check coagulation studies every 2 hours
  4. Fetal scalp electrode
  5. Tocometry or intrauterine pressure catheter
  6. Monitor strict intake and output
    1. Keep Urine Output > 30 cc per hour

XIII. Prognosis

  1. Mortality approaches 61% for mothers
    1. Low survival rate for fetus if still in utero
    2. Surviving mothers have intact neurologic function in only 15% of cases

XIV. References

  1. Krywko and Jennings (2018) Crit Dec Emerg Med 32(4): 3-11
  2. Lively and Clare (2022) Crit Dec Emerg Med 36(5): 4-10
  3. Clark (1995) Am J Obstet Gynecol 172(4): 1158-69 [PubMed]

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