Do babies with isolated single umbilical artery need routine postnatal renal ultrasonography?

The presence of isolated single umbilical artery (SUA) in infants has been associated with an increased risk of occult renal malformations. However, the need for routine postnatal renal imaging of such infants, especially in an era of now routine antenatal fetal sonography, is controversial.

To determine the prevalence of significant renal anomalies and the need for routine postnatal renal imaging in infants with isolated SUA.

Consecutive infants born over 6 years with isolated SUA were offered renal sonography at 4-8 weeks of age. The prevalence of clinically significant renal anomalies in these infants was compared with that detected through routine antenatal fetal scanning and postnatal case findings in a geographically defined control cohort.

During the study period, SUA was found in 137 of 33 067 (4.1/1000) live born infants. Infants with isolated SUA (n = 129) were significantly more likely to be preterm and small for gestational age. 122 infants with isolated SUA (95%) underwent renal ultrasonography; only two infants (1.6%, 95% CI 0.20 to 5.5) had clinically significant renal anomalies, a prevalence similar to that in the control cohort (0.4%, 95% CI 0.29 to 0.45; p = 0.74). Four of eight infants with coexistent systemic malformations had abnormal postnatal renal imaging.

The presence of isolated SUA is associated with increased risk of prematurity and fetal growth restriction. In this largest series of isolated SUA, there was no excess of significant renal malformations among infants with isolated SUA. Postnatal renal ultrasonography is not routinely warranted in such infants.