[Doppler velocimetry in the umbilical, middle cerebral and aortic arteries, before and after cordocentesis].

OBJECTIVE

Prospectively evaluate the effect of cordocentesis on the umbilical, fetal cerebral and aortic circulation.

METHOD

Fetal blood was sampled for diagnostic purposes in 21 pregnant women at 21 to 38 weeks gestation. Ten patients undergoing amniocentesis served as controls. The resistance index (RI) in the umbilical and middle cerebral arteries and the mean blood velocity (Vm) in the descending aorta were measured with pulsed Doppler before and after blood sampling. Variations in umbilical and cerebral RI and in aortic Vm were recorded.

RESULTS

There was a significant drop in both umbilical RI (mean +/- SD = -0.049 +/- 0.078; p = 0.009) and middle cerebral RI (-0.077 +/- 0.058; p < 0.0001) after cordocentesis. The drop in umbilical RI was greater when the second Doppler measurement was made early, when the blood was sampled transplacentally and in early gestational age. Reduction in fetal cerebral artery RI was also greater for transplacental puncture. The fetal descending aorta Vm did not change significantly after blood sampling. There were no variations in Doppler index before and after amniocentesis.

CONCLUSIONS

Changes in blood flow velocity waveforms as measured by pulsed Doppler in the umbilical and fetal cerebral arteries can be induced by fetal blood sampling. Decreased resistance in the placenta and fetal circulation would imply release of nitric oxide.