PB1508 - Massive platelet-rich thrombus formation in small pulmonary vessels in amniotic fluid embolism

Tuesday, June 27, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Atsushi Yamashita, MD, PhD

Professor, Department of Pathology, Faculty of Medicine
University of Miyazaki
Miyazaki, Miyazaki, Japan

Co-Author(s)

TO

Tomoaki Oda

Associate professor, Department of Obstetrics & Gynecology
Hamamatsu University School of Medicine
Hamamatsu, Shizuoka, Japan
MA

Murasaki Aman

Department of Pathology, Faculty of Medicine,
University of Miyazaki
Miyazaki, Miyazaki, Japan
TW

Tomoko Wakasa

Professor, Department of Pathology,
Kinki University Nara Hospital, Kindai University
Ikoma, Nara, Japan
Toshihiro Gi, MD (he/him/his)

Department of Pathology, Faculty of Medicine
University of Miyazaki
Miyazaki, Miyazaki, Japan
RI

Rui Ide

Department of Obstetrics & Gynecology
Hamamatsu University School of Medicine
Hamamatsu, Shizuoka, Japan
YT

Yusuke Todo

Department of Obstetrics & Gynecology
Hamamatsu University School of Medicine
Hamamatsu, Shizuoka, Japan
NT

Naoaki Tamura

Department of Obstetrics & Gynecology
Hamamatsu University School of Medicine
Hamamatsu, Shizuoka, Japan
YS

Yuichiro Sato

Department of Diagnostic Pathology, Miyazaki University Hospital, Faculty of Medicine
University of Miyazaki
Miyazaki, Miyazaki, Japan
HI

Hiroaki Ito

Professor, Department of Obstetrics & Gynecology
Hamamatsu University School of Medicine
Hamamatsu, Miyazaki, Japan
YA

Yujiro Asada

Department of Pathology
Miyazaki Medical Association Hospital
Miyazaki, Miyazaki, Japan

Background: Amniotic fluid embolism (AFE) is characterized by cardiovascular collapse and consumptive coagulopathy; however, it remains unknown whether AFE induces thrombus formation.

Aims: We aimed to identify pulmonary/uterine thrombus formation in AFE.

Methods: We assessed pulmonary and uterine thrombus formation and thrombus area in AFE (n = 11) and pulmonary thromboembolism (PTE; n = 14) on autopsy. 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.

Results: AFE lung sections 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 mm2; p < 0.0001) was significantly smaller than that of uterine thrombus in AFE (0.38 mm2) or PTE (29 mm2). The median area of glycoprotein IIb/IIIa immunopositivity in pulmonary thrombi in AFE (39%; p < 0.01) was significantly larger than that of uterine thrombi in AFE (23%) and PTE (15%). The median area of fibrin (0%; p < 0.001) and citrullinated histone H3 (0%; p < 0.01) immunopositivity in pulmonary thrombi in AFE was significantly smaller than in uterine thrombi (fibrin: 26%; citrullinated histone H3: 1.1%) and PTE (fibrin: 42%; citrullinated histone H3: 0.4%). No mast cells were identified in small pulmonary thrombi.

Conclusion(s): Amniotic fluid may induce distinct thrombus formation in the uterus and lung. Pulmonary and uterine thrombi formation may contribute to cardiorespiratory collapse and/or consumptive coagulopathy in AFE.