Effects of cordocentesis on inferior vena cava velocity waveforms: differences between normally grown and growth-retarded fetuses.

The objective of this study was to analyze the effects of cordocentesis on velocity waveforms recorded from the inferior vena cava and to evaluate differences, if any, in the hemodynamic response between normally grown and growth-retarded fetuses. Twenty-five normally grown fetuses and 20 growth-retarded fetuses were considered for this study. This latter group was characterized by abnormal Doppler indices in the umbilical artery and the middle cerebral artery suggestive of uteroplacental insufficiency as the causative factor of the impaired growth. Flow velocity waveforms were measured from the inferior vena cava immediately before and after cordocentesis and the % reverse flow during atrial contraction calculated. In normally grown fetuses the % reverse flow values did not vary significantly after cordocentesis, while in growth-retarded fetuses this index increased significantly after the procedure (p < or = 0.001). Furthermore, the amplitude of this increase was inversely related to pH levels in umbilical vein (p = 0.004). In conclusion, in growth-retarded fetuses cordocentesis induces an increase of % reverse flow in the inferior vena cava, while no modifications occur in normally grown fetuses. This suggests the presence in growth-retarded fetuses of an impaired cardiac adaptive mechanism to cordocentesis that may explain the higher incidence of complications occurring in such fetuses.