Amniotic fluid embolism: moving diagnosis through the time. From the mechanical pulmonary vascular occlusion until an immuno - inflammatory pathogenesis?

Amniotic fluid embolism (AFE) is a rare, catastrophic syndrome that presents during labor and delivery or immediately postpartum. Efforts to develop a clinical diagnostic test are ongoing; however the diagnosis still relies on rapid bedside evaluation and depends on the exclusion of other diseases. Classically, the diagnosis was made at autopsy, with the demonstration of squamous cells or debris in the maternal pulmonary vasculature. Clinico-pathological correlations have strengthened the evidence for a role of the immune system in the pathogenesis of AFE and have lead to the development of new laboratory tests, such as the serum tryptase and complement measurements, which should provide scientific support for the presumed immunological mechanism of AFE. Recently, studies on the effects of amniotic fluid (AF) on platelet - neutrophil aggregation and neutrophil/platelet activation have opened new insight in the comprehension of the mechanisms underlying AFE, suggesting that a severe inflammatory response might have a paramount causative role, so opening new diagnostic and therapeutic perspectives. Considering the complex interplay between the different mechanisms involved in the pathogenesis of AFE, the diagnosis still arises from a complex diagnostic puzzle in which clinical, macroscopic, laboratory, histological and immunohistochemical data converge toward AFE.