A rare case of amniotic fluid embolism with massive platelet aggregations in pulmonary capillaries

Abstract

A 30-year-old woman at 37 weeks of gestation died during labor induction with oxytocin shortly after an episode of abrupt drop of fetal heart rate. Autopsy showed extensive microvascular plugging of the pulmonary capillaries by massive platelet aggregations. Aside from platelet aggregations, the keratinized substances and granulocytes were also shown in the capillary of pulmonary arterioles. These findings were not observed in other systemic organs (heart, liver, spleen, kidney, adrenal, alimentary canal and pancreas). In general, the postmortem histological diagnosis of amniotic fluid embolism consisted of demonstrating mucus, leukocytes, squamous, amorphous, and fatty cells in the arteries of the lung. To our knowledge, there have not been any reports regarding massive platelet aggregations shown at pulmonary capillaries in case of acute amniotic fluid embolism except for an experimental model. This is a rare case of amniotic fluid embolism in which massive platelet aggregations were confirmed in pulmonary capillaries by autopsy.

Massive platelet‐rich thrombus formation in small pulmonary vessels in amniotic fluid embolism: An autopsy study

“…These findings strongly support the notion that an influx of amniotic fluid materials in the maternal circulation induces maternal inflammatory and anaphylactoid reactions in AFE. However, there is little pathological evidence to suggest haemostatic alteration in AFE, except for the above description 19–21 . The present study provides pathological evidence that amniotic fluid material that enters the uterine venous circulation induces platelet aggregation and activates the coagulation cascade, resulting in thrombus formation.…”

“…However, there is little pathological evidence to suggest haemostatic alteration in AFE, except for the above description. [19][20][21] The present study provides pathological evidence that amniotic fluid material that enters the uterine venous circulation induces platelet aggregation and activates the coagulation cascade, resulting in thrombus formation. However, the uterine venous thrombi were not observed in half of the AFE cases.…”

“…10 in this study) of AFE with massive platelet aggregation in the pulmonary arteries and capillaries. 21 Therefore, we focused on thrombus formation in AFE in this study.…”

Different Clinical Courses with Severe Postpartum Coagulopathy in Two Cases Showing the Same Histological Findings those Local Amniotic Fluid Emboli

“…It is currently thought that the AFE develops after a complex reaction based on the type of fetal components, the amount of fetal components, and immunological reaction of maternal including complement activation, anaphylaxis, and inflammatory response [3,4,15]. We also experienced a case of AFE with massive platelet aggregations in pulmonary capillaries [16], suggesting platelet-activating factor (PAF) might have involved in. Therefore, laboratory test including the measurement of serum tryptase, complement, or PAF activity might be helpful to support the diagnosis of AFE.…”