Amniotic fluid embolism: despite progress, challenges remain

This article reviews the incidence, pathophysiology, risk factors, diagnosis, and management of amniotic fluid embolism (AFE). AFE is a leading cause of maternal morbidity and mortality despite an incidence of approximately 7 to 8 per 100,000 births. Recent reevaluation of AFE suggests that the presence of fetal tissue in maternal circulation alone is not sufficient to cause the clinical syndrome, but rather an individual's response to this fetal tissue. The 'anaphylactoid reaction' associated with AFE shares many clinical and metabolic aspects of septic shock. Acute dyspnea followed by cardiovascular collapse, coagulopathy, and neurological symptoms, such as coma and seizures may all be associated with the clinical AFE syndrome. Specific biochemical markers have been described, but are of limited clinical value because of the rapid progression of the disease process. Treatment is based on an interdisciplinary approach that consists of a combination of prompt, aggressive hemodynamic resuscitation, provision of end-organ support, correction of hemostatic disorders, and delivery. Although AFE cannot be prevented, early diagnosis and intervention may lead to better outcomes for both the mother and the fetus. Clinical suspicion, traditional laboratory data, or intravascular cellular debris (demonstrated only in 50% of patients) are insufficient to make a definitive diagnosis of AFE. An evolving array of novel biomarkers may help differentiate AFE from other conditions, but none of them currently provide sufficient 'early warning' ability to make real-time impact on diagnosis and/or treatment of AFE.