What is amniotic fluid embolism (AFE)?

From the Guidelines

Amniotic fluid embolism (AFE) is a rare and potentially life-threatening obstetric emergency characterized by the sudden onset of hypotension, hypoxia, and either consumptive coagulopathy or severe bleeding 1.

Key Characteristics

• The syndrome is believed to be triggered by the abnormal release of trophoblasts or other material into the maternal circulation 1.
• The reported incidence is 1.9 to 6.1 per 100,000 births, and the case fatality rate has been reported to exceed 50% in “classic” cases characterized by cardiovascular collapse and coagulopathy 1.

Diagnosis and Management

• AFE should be considered in the differential diagnosis in any pregnant or immediately postpartum woman who suffers sudden cardiovascular collapse or cardiac arrest, seizures, severe respiratory difficulty, or hypoxia, particularly if such events are followed by a coagulopathy that cannot be otherwise explained 1.
• Management involves immediate supportive care, including administration of oxygen, fluid resuscitation, and blood products as needed, with consideration of uterotonic agents such as oxytocin or methylergonovine to control postpartum hemorrhage 1.
• Corticosteroids, such as methylprednisolone, may be considered to mitigate the inflammatory response associated with AFE.
• Hemodynamic support is crucial, and may involve the use of vasopressors such as norepinephrine or vasopressin, and inotropic agents such as dobutamine and milrinone 1.

Important Considerations

• Excessive fluid administration should be avoided, particularly in the setting of a massively dilated right ventricle, as this can increase the risk of right-sided myocardial infarction 1.
• Left ventricular failure with cardiogenic pulmonary edema may become the prominent finding in the later stages of AFE, and should be treated by optimizing cardiac preload 1.

From the Research

Definition and Pathophysiology of Amniotic Fluid Embolism (AFE)

• Amniotic fluid embolism (AFE) is a rare, sudden, and catastrophic complication of pregnancy that can result in cardiopulmonary arrest, potentially leading to death 2.
• The pathophysiology of an AFE includes an inflammatory and coagulopathic response due to fetal materials entering maternal circulation with the hallmark triad of symptoms: acute respiratory distress, cardiovascular collapse, and coagulopathy 2.
• AFE is a life-threatening obstetric emergency characterized by high maternal mortality, and early recognition and prompt treatment are crucial for improving the prognosis 3.

Clinical Manifestations and Diagnosis of AFE

• The clinical manifestations of AFE are heterogeneous, leading to misdiagnosis or treatment delay 4.
• The main symptoms of AFE include dyspnea, cardiovascular collapse, disseminated intravascular coagulation (DIC), and even sudden cardiac death 5.
• Four diagnostic criteria proposed by the Society for Maternal-Fetal Medicine (SMFM) may accelerate diagnosis 5.

Management and Treatment of AFE

• Management of AFE should include high-quality cardiopulmonary resuscitation, immediate delivery of the fetus if applicable, early intubation to provide adequate oxygenation and ventilation, fluid volume resuscitation, and ongoing evaluation of coagulopathy 2.
• Priorities include thromboelastography interpretation if available, control of hemorrhage and coagulopathy with blood component therapy, and cardiovascular support through inotropes and vasopressor administration 2.
• More recent approaches include implementing the A-OK (atropine, ondansetron, and ketorolac) protocol for suspected AFE protocol, extracorporeal cardiopulmonary resuscitation (ECPR), and extracorporeal membrane oxygenation (ECMO) therapies to increase survival and decrease complications 2.