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.

Amniotic fluid embolism.

Amniotic fluid embolism remains one of the most devastating conditions in obstetric practice with an incidence of approximately 1 in 40,000 deliveries and a reported mortality rate ranging from 20% to 60%. The pathophysiology appears to involve an abnormal maternal response to fetal tissue exposure associated with breaches of the maternal-fetal physiologic barrier during parturition. This response and its subsequent injury appear to involve activation of proinflammatory mediators similar to that seen with the classic systemic inflammatory response syndrome. Progress in our understanding of this syndrome continues to be hampered by a lack of universally acknowledged diagnostic criteria, the clinical similarities of this condition to other types of acute critical maternal illness, and the presence of a broad spectrum of disease severity. Clinical series based on population or administrative databases that do not include individual chart review by individuals with expertise in critical care obstetrics are likely to both overestimate the incidence and underestimate the mortality of this condition by the inclusion of women who did not have amniotic fluid embolism. Data regarding the presence of risk factors for amniotic fluid embolism are inconsistent and contradictory; at present, no putative risk factor has been identified that would justify modification of standard obstetric practice to reduce the risk of this condition. Maternal treatment is primarily supportive, whereas prompt delivery of the mother who has sustained cardiopulmonary arrest is critical for improved newborn outcome.

Amniotic fluid embolism: historical perspectives & new possibilities.

Amniotic fluid embolism (AFE) is a rare obstetric catastrophe that occurs suddenly and without warning. AFE is a condition that is poorly understood and often difficult to diagnose, but has a high maternal and neonatal morbidity and mortality. Since it was first described in 1926, the underlying pathophysiology has eluded researchers and clinicians. While a new understanding of the syndrome has emerged with the advent of a national registry in the 1980s, recommendations for diagnostic methods and treatment in the acute phase of the event remain unclear. The purpose of this article is to provide the reader with a historical look at the phenomenon of AFE, a description of its suspected pathophysiology, and recommendations for nursing interventions. A review of data from the national registry and other classic studies are included.