Longitudinal Doppler ultrasonographic assessment of alterations in regional vascular resistance of arteries in normal and growth-retarded fetuses.

The objective of this longitudinal study was to evaluate alterations in regional vascular resistance of arteries with advancing gestation in normal and growth-retarded fetuses. Color Doppler flow imaging and pulsed Doppler ultrasonographic assessments were performed on 13 normal and 7 growth-retarded fetuses, ranging from 15 to 40 weeks menstrual age. The pulsatility index was calculated for middle cerebral artery, descending aorta, splenic artery, renal artery, femoral artery and umbilical artery, respectively. Optimal models for these pulsatility index values were determined by regression analysis. A normal range of the pulsatility index for each artery generated in the normal fetuses. In the middle cerebral artery, the models showed a parabolic pattern during pregnancy in the two groups and the predicted pulsatility index values in growth-retarded fetuses were always lower than those in the normal fetuses, especially late in pregnancy. In the renal artery, the predicted pulsatility index values in growth-retarded fetuses were higher than those in normal fetuses near term. In other arteries, the predicted pulsatility index values showed their own specific patterns and there were no significant differences in predicted pulsatility index values in the two groups. In conclusion, alterations in regional vascular resistance of arteries with advancing menstrual age occur evidenced in both normal and growth-retarded fetuses.