Amniotic Fluid Embolism

On this page

AFE Pathophysiology - Deadly Domino Effect

Amniotic Fluid Embolism (AFE) is a rare (1 in 40,000), unpredictable, catastrophic obstetric emergency.

  • Trigger: Entry of amniotic fluid and fetal cellular components (squames, hair, vernix) into maternal circulation. This initiates a complex, incompletely understood anaphylactoid or SIRS-like immune/inflammatory response, not purely embolic.
  • Key Risk Factors: Advanced maternal age (>35), multiparity, operative delivery (C-section, forceps), placental abruption/previa, polyhydramnios, uterine rupture, induction of labor, eclampsia.
  • Mediators: Key substances implicated include endothelin, leukotrienes, prostaglandins, bradykinin, serotonin, thromboxane A2, and tissue factor, activating various pathways.

Amniotic Fluid Embolism Pathophysiology

⭐ AFE is considered an anaphylactoid or SIRS-like reaction to fetal material, not just a mechanical obstruction.

AFE Clinical Presentation - Sudden Storm Signs

  • Onset: Sudden, dramatic. Typically during labor, delivery (vaginal/CS), or within 30 mins postpartum. May occur with D&C, amniocentesis.
  • Classic Triad 📌 HHC:
    • Hypoxia: Acute dyspnea, cyanosis, ↓SpO2, respiratory arrest.
    • Hypotension: Cardiovascular collapse, tachycardia, cardiac arrest.
    • Coagulopathy: DIC, severe uncontrollable hemorrhage, oozing from sites.
  • Neurological Signs (if not arrested): Seizures, agitation, confusion, loss of consciousness.
  • Other Manifestations:
    • Fetal distress (bradycardia, late decelerations).
    • Chills, shivering, nausea, vomiting.
    • Sense of impending doom.

⭐ The rapid onset of the triad (hypoxia, hypotension, coagulopathy) is highly characteristic of AFE.

AFE Diagnosis & Differentials - The Great Mimicker

  • Diagnosis of Exclusion: No specific test; clinical diagnosis after ruling out others.
  • Supportive Investigations (Rule out others):
    • ABG: Severe hypoxemia, metabolic acidosis.
    • Coagulation: DIC (↑PT/APTT, ↓fibrinogen, ↑FDP/D-dimer, ↓platelets).
    • ECG: RV strain (e.g., S1Q3T3), ST changes, arrhythmias.
    • CXR: Normal initially, or bilateral infiltrates/pulmonary edema.
    • Echo: Acute RV dilatation/failure, LV dysfunction, pulmonary HTN.
  • Histopathology (Often Postmortem): Fetal elements (squames, lanugo, mucin) in maternal pulmonary vessels.

    ⭐ Finding fetal elements in maternal circulation is not diagnostic of AFE as they can be present in healthy parturients.

  • Key Differentials:
    • Pulmonary Embolism (Thromboembolic)
    • Eclampsia
    • Anaphylaxis
    • Septic Shock
    • Aspiration Pneumonitis
    • Myocardial Infarction
    • High Spinal Block
    • Uterine Atony & Hemorrhage
    • Transfusion Reaction Amniotic fluid embolism histology

AFE Management & Prognosis - Code Blue Crisis

📌 Mnemonic: AFE CRASH (Coagulation, Respiratory, Arrest, Shock, Help!)

  • Multidisciplinary Team: Obstetrician, Anesthesiologist, Intensivist, Hematologist, Nursing.
  • Immediate Resuscitation (ABCD):
    • Airway: Intubation, 100% O2.
    • Breathing: Mechanical ventilation.
    • Circulation: IV access, aggressive fluids, vasopressors (norepinephrine, epinephrine), inotropes. CPR if cardiac arrest.
  • Delivery of Fetus: Expedite (within 3-5 minutes of arrest if possible) to aid maternal resuscitation.
  • Manage Coagulopathy/DIC:
    • Massive Transfusion Protocol (MTP): RBCs:FFP:Platelets:Cryoprecipitate $1:1:1:1$.
    • Tranexamic acid. Consider Factor VIIa.
  • Specific/Supportive Therapies: ECMO, A-OK cocktail (Atropine, Ondansetron, Ketorolac), Corticosteroids (evidence limited).
  • Prognosis: High maternal mortality (20-60%+), often with neurological deficits. High fetal mortality/morbidity.

⭐ Early and aggressive supportive care, including prompt management of cardiovascular collapse and DIC with component therapy, is the cornerstone of AFE management.

High‑Yield Points - ⚡ Biggest Takeaways

  • Sudden cardiovascular collapse, respiratory distress, and coagulopathy during labor or immediately postpartum are classic signs.
  • Disseminated Intravascular Coagulation (DIC) is a hallmark, leading to profuse hemorrhage.
  • Pathophysiology involves an anaphylactoid-like reaction to fetal material entering maternal circulation, not a true embolism.
  • Diagnosis is primarily clinical and often one of exclusion; no specific diagnostic test exists.
  • Management is aggressive supportive care: ABC (Airway, Breathing, Circulation), oxygenation, IV fluids, vasopressors, and massive transfusion protocol.
  • Associated with high maternal and neonatal mortality and morbidity.
  • Key features include hypoxia, hypotension, seizures, and cardiac arrest within minutes to hours of onset.

Practice Questions: Amniotic Fluid Embolism

Test your understanding with these related questions

A pregnant female at 37 weeks of gestation with a history of prosthetic heart valves is currently taking warfarin. She comes for a routine antenatal check-up. What is the appropriate management advice?

1 of 5

Flashcards: Amniotic Fluid Embolism

1/8

_____ anesthesia is the first choice for most patients with preeclampsia during labor, vaginal delivery, and cesarean section

TAP TO REVEAL ANSWER

_____ anesthesia is the first choice for most patients with preeclampsia during labor, vaginal delivery, and cesarean section

Epidural

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial