Amniotic fluid embolus: a review of the research literature

The diagnosis of Amniotic Fluid Embolus (AFE) is often missed clinically leading to the incorrect attribution of a major post-partum haemorrhage, which may accompany AFE, to uterine atony. This paper reviews the research on AFE with particular emphasis on the clinical presentation and diagnosis; both before and after death. It begins by dealing with the difficulty of defining AFE due to confusion about the underlying pathophysiological events. As this paper will demonstrate, the theory that AFE is an embolic event is no longer valid. A description of the clinical manifestations is provided so that these can be explained by the contemporary theory of AFE as an 'anaphylactoid' reaction. Finally, the difficulties of diagnosis, particularly laboratory diagnosis, will be discussed. The research indicates that it is not possible to accurately diagnose AFE, either, pre or post mortem, by any currently available laboratory tests. Because of better diagnosis it is now known that AFE in not uncommon and, if it is diagnosed early, a much higher rate of intact survival can be achieved than was previously thought possible.