Key result
An abnormal umbilical artery flow velocity waveform was significantly associated with small-for-gestational age fetuses (P<0.002) and increased whole blood viscosity at high shear.
Why the study?
Is there an association between umbilical cord whole blood viscosity and umbilical artery flow velocity time waveforms?
Observational
Is there an association between umbilical cord whole blood viscosity and umbilical artery flow velocity time waveforms?
Abnormal umbilical artery flow velocity waveforms are associated with increased whole blood viscosity at high shear rates, though small-for-gestational age is only significantly associated with the abnormal waveform and not the viscosity itself.
Abnormal umbilical waveforms associate with higher viscosity in SGA; hypothesis-generating and should not yet change fetal surveillance practice.
The possibility was examined of an association between umbilical cord whole blood viscosity and umbilical artery flow velocity time waveforms obtained with continuous wave Doppler ultrasound. The cord blood viscosity was measured at both high (100 s-1) and low (0.1 s-1) shear rates with a concentric cylinder viscometer. Plasma viscosity and fibrinogen were also measured. An abnormal pattern in the umbilical artery flow velocity waveform (high A/B ratio) indicative of high resistance was associated with an increase in whole blood viscosity at high shear (which may reflect a change in red cell rigidity). Viscosity at low shear (reflecting red cell aggregation and rouleaux formation) did not differ. There was a significant association between the small-for-gestational age fetus and abnormal umbilical artery waveform study (P less than 0.002) but not abnormal whole blood viscosity at high (P = 0.09) or low (P = 0.08) shear.
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Giles et al. (1986) conducted an observational in Fetal growth restriction / Pregnancy. Abnormal umbilical artery flow velocity waveform and umbilical cord whole blood viscosity was evaluated on Association with small-for-gestational age fetus (p=<0.002). An abnormal umbilical artery flow velocity waveform was significantly associated with small-for-gestational age fetuses (P<0.002) and increased whole blood viscosity at high shear.
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