An amniotic fluid embolism (AFE), or anaphylactoid syndrome of pregnancy, is an acute life-threatening event that occurs most often during labor and delivery. Mortality has been noted to approach 60%, with the majority of survivors incurring significant neurologic damage.

Patients will present with sudden onset of hypotension, hypoxia, tachycardia, and cyanosis that will quickly progress (in seconds to minutes) to pulmonary edema, shock, respiratory failure, disseminated intravascular coagulation (DIC), seizures, and cardiovascular collapse or cardiac arrest. Sometimes the first sign / symptom will be cardiac arrest.

The etiology for these events is unknown but thought to be related to amniotic fluid entering maternal circulation due to some type of trauma or disruption of the placenta (vaginal or cesarean delivery, amniocentesis, abdominal trauma, uterine rupture, or second trimester dilation and evacuation) and subsequent maternal inflammatory reaction similar to what occurs in septic shock. Usually, if this is going to occur postpartum, it is within 30 minutes of delivery.

There are few identifiable risk factors to help predict when and in whom an AFE will occur. Risk factors include placental abruption, operative delivery, and abnormal placentation (placenta previa / accreta), with the proposed mechanism possibly being an increased surface area for maternal-fetal exchange.
    
In addition, no management outcomes have been shown to improve survival after this type of event.
   
If an AFE occurs while the infant is still in utero, fetal distress is frequent, and there may be significant sequelae for the infant as well (neurologic outcomes are often poor and related to hypoxic / ischemic issues).