CARDIAC FLOW AFTER FETAL BLOOD-SAMPLING IN NORMALLY GROWN AND GROWTH-RETARDED FETUSES

The objective of this study was to evaluate the effect of fetal blood sampling on cardiac flow velocity waveforms. Flow velocity waveforms w ere measured from the ascending aorta and pulmonary artery immediately before and after fetal blood sampling in 29 normally grown and 12 gro wth-retarded fetuses. The latter group was characterized by abnormal D oppler indices in the umbilical artery and middle cerebral artery sugg estive of uteroplacental insufficiency as the causative factor of the impaired growth. The flow velocity parameters studied were the peak ve locity, the time to peak velocity, and the left and right cardiac outp ut and their ratio. In normally grown fetuses, the peak velocity and r ight and left cardiac output values increased significantly after feta l blood sampling, while no significant changes were observed in the ot her indices considered. The gestational age at the time of the procedu re was positively related to the amplitude of these changes. In growth -retarded fetuses, fetal blood sampling did not induce any significant increase in cardiac output or peak velocities, while in more than 50 per cent of the fetuses these Doppler indices decreased. The amplitude of the decrease was significantly related to the severity of acidosis in the umbilical vein, In conclusion, the cardiac haemodynamic respon se to fetal blood sampling differs between normally grown and growth-r etarded fetuses. This difference may explain the higher rate of compli cations occurring in the latter group of fetuses after blood sampling.