Massive platelet-rich thrombus formation in small pulmonary vessels in amniotic fluid embolism: an autopsy study

To identify pulmonary/uterine thrombus formation in amniotic fluid embolism (AFE). Retrospective, observational. Nationwide. Eleven autopsy cases of AFE and control cases. We assessed pulmonary and uterine thrombus formation and thrombus area in AFE and pulmonary thromboembolism (PTE) as a control. The area of platelet glycoprotein IIb/IIIa, fibrin, neutrophil elastase, citrullinated histone H3 (a neutrophil extracellular trap marker) and mast cell chymase immunopositivity was measured in 90 pulmonary emboli, 15 uterine thrombi and 14 PTE. Pathological evidence of thrombus formation and its components in AFE. Amniotic fluid embolism lung showed massive thrombus formation, with or without amniotic emboli in small pulmonary arteries and capillaries. The median pulmonary thrombus size in AFE (median, 0.012 mm ; P