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Aim To evaluate whether the presence of amniotic components in the maternal uterine vasculature could be a specific pathological indicator for amniotic fluid embolism ( AFE). Methods Medical records of patients treated between January 2006 and March 2013 were retrospectively examined to identify patients who underwent post-partum hysterectomy or autopsy due to maternal death. Three subjects with AFE with disseminated intravascular coagulation ( DIC)-type post-partum hemorrhage ( PPH), and 13 non- AFE subjects were included in analysis. Histochemical staining using hematoxylin-eosin (HE) and alcian blue, and immunohistochemical staining for sialyl- Tn were conducted to detect amniotic components in the maternal uterine vasculature. Results Alcian blue was positive for amniotic components in the uterine vasculature of all subjects with AFE and of several subjects without AFE. Similarly, HE and sialyl- Tn were negative in some AFE subjects and positive in some non- AFE subjects. Conclusions The presence of maternal intravascular fetal material is not a specific indicator for AFE with DIC-type PPH. Therefore, the presence of fetal components in the uterine vasculature is unlikely to be a definitive indicator for AFE. [ABSTRACT FROM AUTHOR]

Objectives: The purpose is to investigate how umbilical arterial blood flow changes by an intraamniotic distilled water infusion and to determine whether the changes in umbilical circulation have any relationship with fetal cardiovascular status and osmolality in amniotic fluid and fetal plasma. Methods: Eleven chronically catheterized pregnant sheep were used in this study. After a 1-hour control period, 1.5 L of warmed sterile distilled water was injected over 10 minutes into the amniotic cavity. Fetal heart rate and carotid arterial pressure, blood flow of the umbilical and fetal carotid arteries were continuously measured. Fetal arterial blood sampled twice during the control period and then at 30, 60, 90, 120, 180, 240, 300, and 360 minutes after the start of the infusion, was analyzed for blood gases, pH, plasma electrolytes, and osmolality. Results: Data obtained from seven sheep with normoxemic fetuses were studied statistically. Umbilical arterial blood flow decreased significantly from 229.5 ± 3.83 mL/min in the control to 167.4 ± 11.1 mL/min at 30 minutes after water infusion (P <.001). Umbilical arterial vascular resistance increased rapidly and reached its peak at approximately 60 minutes after infusion and then showed a gradual recovery to the control level (P <.001). Amniotic fluid osmolality had a high degree of correlation with umbilical arterial blood flow and vascular resistance, while fetal arterial blood pressure and heart rate had only little correlation with umbilical blood flow. Conclusion: A distilled water infusion into the amniotic cavity in near-term pregnant sheep led to an acute drop in umbilical arterial blood flow. The changes in umbilical flow were closely correlated with those in amniotic fluid osmolality. Hemolysis in the capillary networks in the fetal membranes seems to be one of the main causes of umbilical vasoconstriction. It is speculated that the fetal membranes, including capillary networks, intramembranous pathway, and amnion epithelial cells, sense the changes in amniotic fluid osmolality, which leads to a fetal adaptation to the hypotonic environment. [Copyright &y& Elsevier]