Amniotic fluid embolism: the known and not known

Area of Science:

• Obstetrics and Gynecology
• Pathology
• Immunology

Background:

• Amniotic fluid embolism (AFE) was first described in 1926, characterized by fetal material in maternal pulmonary vasculature.
• The condition has an incidence of 2-8 per 100,000 births with a high mortality rate (13-35%).
• Diagnosis in living patients is difficult, relying on clinical signs like circulatory collapse and respiratory distress.

Purpose of the Study:

• To review the historical context, diagnostic challenges, and potential mechanisms of amniotic fluid embolism.
• To highlight the diagnostic paradox between autopsy findings and clinical presentation.
• To explore current research into diagnostic markers and etiological factors.

Main Methods:

• Review of historical case reports and literature.
• Analysis of diagnostic criteria and limitations.
• Discussion of proposed etiological mechanisms, including complement activation.

Main Results:

• Autopsy confirmation of fetal material in pulmonary vasculature is specific for AFE.
• Clinical diagnosis relies on a constellation of signs, but lacks definitive laboratory confirmation in living patients.
• Serum tests for fetal antigen, insulin-like growth factor binding protein-1, and complement are under investigation.

Conclusions:

• The definitive diagnosis of amniotic fluid embolism remains reliant on autopsy findings.
• Complement activation is a potential mechanism, while mast cell degranulation is unlikely.
• The reason why only a small subset of women develop AFE remains a significant unknown.