Clinical Presentation of Amniotic Fluid Embolism
Amniotic fluid embolism presents as a sudden, catastrophic triad of acute hypoxia, hypotension, and coagulopathy occurring during labor, delivery, or the immediate postpartum period. 1
Classic Presentation
The hallmark features include:
- Sudden cardiovascular collapse with hypotension or cardiac arrest (pulseless electrical activity, asystole, ventricular fibrillation, or pulseless ventricular tachycardia) 2
- Acute respiratory distress with severe hypoxemia and respiratory failure 1
- Coagulopathy with disseminated intravascular coagulation (DIC), which may have immediate or delayed onset following the cardiovascular collapse 1, 2
Prodromal Symptoms
Before the catastrophic collapse, patients may experience:
- Anxiety, agitation, or mental status changes 2
- A sensation of impending doom 2
- Generalized tonic-clonic seizures 3, 4
These warning signs may precede the full cardiovascular collapse by minutes, making recognition critical.
Timing and Context
70% of AFE cases occur during labor, 11% after vaginal delivery, and 19% during cesarean delivery. 1 The mode of delivery alters timing but not overall risk. 1
Rare presentations can occur during:
Pathophysiologic Phases
The presentation follows a biphasic pattern:
Phase 1 (Early): Right ventricular failure dominates due to pulmonary vasoconstriction and mechanical obstruction from amniotic fluid components entering maternal circulation. 1, 2 This causes acute pulmonary hypertension and right heart strain.
Phase 2 (Late): Left ventricular failure develops with cardiogenic pulmonary edema and systemic hypotension. 1, 2
Key Diagnostic Considerations
AFE remains a clinical diagnosis of exclusion—no specific laboratory or imaging test can confirm or refute it. 1, 2, 5 The diagnosis requires:
- Presence of the classic triad (hypoxia, hypotension, coagulopathy) 1
- Temporal relationship to labor/delivery 1
- Exclusion of other causes of sudden cardiorespiratory collapse 1
Bedside transthoracic echocardiography demonstrating right ventricular dysfunction is the most helpful diagnostic modality when AFE is suspected. 2
Common Pitfalls
AFE is often initially misdiagnosed because of its rarity and dramatic presentation. 5 Maintain high clinical suspicion in any pregnant or immediately postpartum woman with sudden cardiovascular collapse, seizures, severe respiratory difficulty, or unexplained coagulopathy. 1
Coagulopathy may not be immediately apparent but can develop rapidly and become life-threatening. 5 Early assessment of clotting status (PT/INR, aPTT, fibrinogen, platelet count, D-dimer) is essential. 5
Do not delay resuscitation waiting for diagnostic confirmation. Immediate high-quality CPR following ACLS protocols must begin without waiting for imaging or laboratory results. 2, 5