FETAL ATRIOVENTRICULAR, VENOUS, AND ARTERIAL FLOW VELOCITY WAVE-FORMSIN THE SMALL-FOR-GESTATIONAL-AGE FETUS

Arterial, venous, and intracardiac Doppler how velocity waveforms were studied in 50 women with a small for gestational age (SGA) fetus acco rding to a cross-sectional study design. No Doppler signals could be o btained in five women for technical reasons. The remaining 45 women we re compared with normal control subjects matched for gestational age a nd maternal parity. The 45 SGA fetuses were divided into birth weight below the 5th centile for gestational age (group I, n = 35) and birth weight between the 5th and 10th centile for gestational age (group II, n = 10). A significant difference in baseline characteristics was fou nd between both SGA subsets and normal controls. In SGA I fetuses, the pulsatility index in the umbilical artery and descending aorta was si gnificantly higher, but lower in the middle cerebral artery when compa red with normal controls. At the atrioventricular and venous level (um bilical vein, ductus venosus, and inferior vena cava) reduced time-ave raged velocities were established. PIV in the ductus venosus and IVC s howed a significant increase. Within the same SGA subset, no relations hip could be established between arterial downstream impedance and 1) atrioventricular flow velocities and 2) pulsatility index in the ductu s venosus and inferior vena cava. Also, no relationship existed betwee n flow velocity waveforms and pregnancy-induced hypertension and admis sion to the neonatal intensive care unit. Umbilical venous pulsations and absent/reverse flow in the umbilical artery were associated with a high intrauterine mortality rate and low birth weights. In SGA II fet uses, the pulsatility index in the umbilical artery and decending aort a was significantly higher than in normal controls. It can be conclude d that fetuses with a birth weight below the 5th centile demonstrate m arked changes in arterial, atrioventricular, and venous flow velocity waveforms. Atrioventricular and venous flow velocity waveforms change independently from arterial downstream impedance, suggesting that othe r factors, such as reduced volume how and myocardial contraction force , may play a role in the observed changes.