Ultrasound predictors of birth weight in euploid fetuses with isolated single umbilical artery.

OBJECTIVE

To evaluate ultrasound parameters, including Doppler assessment, that may influence fetal growth and birth weight in cases of isolated single umbilical artery (SUA).

METHODS

Sixty pregnant women with isolated SUA were studied. Doppler measurements of umbilical artery (UA), mean uterine artery (UtA) and fetal middle cerebral artery (MCA) pulsatility indices (PI) were recorded and the corresponding Z-scores were calculated according to gestational age at time of measurement. Additionally, the umbilical vein (UV) to UA diameter and perimeter ratios were calculated. The relationships between ultrasound parameters and customized birth-weight centiles according to sex and gestational age were analyzed.

RESULTS

There were significant correlations between birth-weight centile and the Z-score of mean UtA-PI (r = - 0.417, P = 0.008) and the UV to UA perimeter ratio (r = 0.567, P = 0.001). A significant positive correlation between Z-scores of UA-PI and mean UtA-PI (r = 0.428, P = 0.007) was also found. When using stepwise linear regression analysis both mean UtA-PI Z-scores and UV to UA perimeter ratio were included in the predictive model of birth-weight centile (R(2) = 0.46, P < 0.001).

CONCLUSIONS

Doppler assessment of mean UtA-PI and the UV to UA perimeter ratio may be useful in the clinical management of isolated SUA cases by identifying a subgroup at higher risk for fetal growth restriction.