Ancillary Studies in Amniotic Fluid Embolism

Abstract

The incidence of amniotic fluid embolism during pregnancy is approximately 1/50,000 and has a mortality rate in excess of 80%. The postmortem diagnosis of amniotic fluid embolism can be challenging for forensic investigators and pathologists. At autopsy, usually signs of disseminated intravascular coagulation suggest an amniotic fluid embolism. A definitive diagnosis of amniotic fluid embolism cannot be made until ancillary studies are performed on the decedent's tissues. We report a case of a 37-year-old G3P2 white female who was 36 weeks gestation when her membranes spontaneously ruptured. She suddenly became breathless, went into cardiogenic shock, and died. The autopsy revealed gross and microscopic findings of amniotic fluid embolism, which was confirmed with ancillary studies consisting of special stains, immunohistochemistry, and a serum tryptase level. The authors hope this case report, including gross and microscopic autopsy findings with procedural and ancillary studies, and review of the literature will help investigators and pathologists in the diagnosis of amniotic fluid embolism.

Amniotic fluid embolism: an evidence-based review

“…2,78 These constituents can be specifically identified by using immunohistochemical markers for cytokeratin AE1/AE3, Alcian blue or mucicarmine staining, oil red O staining, and polarized light, respectively. 81–83 Kobayashi et al, 84 reported that immunohistochemical staining using monoclonal antibody TKH-2 is a more sensitive method to detect meconium and amniotic fluid-derived mucin in the lung sections of patients with AFE than conventional hematoxylin eosin or Alcian blue staining. Oi et al 85 reported positive TKH-2 staining within the pulmonary vasculature in 14 of 15 (93%) women with AFE.…”

“…Increased serum levels of tryptase, a marker of mast cell degranulation, in women with AFE have been reported by some authors 123,124 but not by others. 83,125 Benson et al 57 reported that serum tryptase was negative in all of the 6 women with AFE. However, they found that decreased serum levels of C3 and C4 complement had sensitivities between 88–100% and a specificity of 100% for the diagnosis of AFE.…”

Amniotic Fluid Embolism

“…3,10,12,13 Increased tryptase levels have been used to attempt AFE diagnosis, with the theory that AFE may be equated to anaphylaxis. PAF is thought to cause increased vascular permeability; bronchoconstriction; platelet aggregation; recruitment of leukotrienes, cytokines, and thromboxanes; and a prostaglandin cascade.…”