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The coagulation system in placental insufficiency: a study in the fetal circulation
G R Wilcox1, B J Trudinger, T Exner
1Department of Obstetrics and Gynaecology, University of Sydney, Westmead Hospital, Australia.
Objective:
To examine the hypothesis that Doppler-defined umbilical placental insufficiency is associated with intravascular coagulation in the fetal circulation.
Design:
A prospective, descriptive, single centre study.
Setting:
The University of Sydney, Department of Obstetrics at Westmead Hospital.
Subjects:
Ninety-one infants were classified on the basis of the systolic:diastolic (SD) ratio of the umbilical artery flow velocity waveforms into severe (SD > 99.9th centile), moderate (SD > 95th centile) or control groups.
Intervention:
Blood was collected from the umbilical vein at delivery.
Main Outcome Measures:
The coagulation variables measured were the plasma concentrations of thrombin-antithrombin, fibrinopeptide A and fibrinogen, the antithrombin III activity, the prothrombin time and the activated partial thromboplastin time.
Results:
There were no differences in activated partial thromboplastin time, antithrombin III activity, fibrinopeptide A or thrombin-antithrombin complex concentrations between fetuses with placental insufficiency and those with no placental disease. Fetuses with severe and moderate placental insufficiency had a statistically significant prolongation of their mean prothrombin time compared to controls (23.7 +/- 0.8, 23.6 +/- 1.6, and 19.9 +/- 0.6 s, respectively). Infants in the severe group had a lower plasma fibrinogen concentration than control fetuses (1.66 +/- 0.09 and 1.94 +/- 0.09 g/l, respectively). The activated partial thromboplastin time and antithrombin III activity were both highly dependent on gestational age.
Conclusions:
These results do not support the hypothesis that Doppler-defined umbilical placental insufficiency is associated with activation of coagulation in the fetal circulation.