Assessment of Fetal Renal Volume Using Three-Dimensional Ultrasound and its Relation to Fetal Growth and Placental Blood Flow

Objective: Intrauterine growth restriction may lead to renal disease and hypertension in adult life. This study was performed to determine whether renal volume differs between fetuses that are intrauterine growth restricted and fetuses that are not. We also aimed to examine the association of fetal blood flow parameters, the amniotic fluid index with the fetal renal volume. Patients and Methods: Fetal biometry was examined in 200 pregnant women between 27 and 36 weeks of gestation. Women were divided into two groups: mothers with intra-uterine growth restricted fetus (group A, n=17) and mothers within normal range fetal biometry i.e. control group (group B, n=183). In all participants, total renal volume was measured using 3D ultrasound and umbilical as well as the middle cerebral artery resistance index which was calculated using color Doppler technique. All measured parameters were compared to fetal growth state and correlated to the total renal volume. Results: The mean total fetal renal volume was 10.26±2.62 in group A and 16.85±5.35 in group B. (p value 0.0001). Head circumference, abdominal circumference and estimated fetal weight were positively correlated with the total renal volume TRV in both groups r=0.7, 0.72, 0.8 respectively in Gp A, and 0.7, 0.6, 0.7 respectively for Gp B, with a statistically significant p value for both groups. Umbilical artery resistance index was inversely correlated with the total renal volume in group A (r=-0.70, p 0.002). The middle cerebral artery resistance index did not show a significant correlation with the TRV in group A r=0.37, p=0.2 in contrast to the control group where a significant negative correlation existed between the 2 parameters r=-0.4, p=0.0001. The amniotic fluid index showed a positive correlation with the TRV in both groups r=0.5, p=0.04 in Gp A, and r=0.2, p= 0.02 for Gp B. Conclusion: Intrauterine growth restriction appears to be associated with a decrease in fetal renal volume. This study supports the hypothesis that intrauterine growth restriction may be linked to renal disease and hypertension in late life.