Isolated single umbilical artery--the case for routine renal screening.

To determine the incidence of silent renal anomalies in infants with isolated single umbilical artery (SUA), all infants with SUA and without other obvious congenital anomalies, identified over a six year period, were screened using renal ultrasonography. Over 35,000 placentas were examined. An isolated single umbilical artery was identified in 112 (0.32%). Nineteen infants had abnormal renal imaging. Eight of 112 (7.1%) had significant persisting abnormalities. Vesicoureteric reflux was found in five infants (4.5%). It is recommended that renal ultrasonography be performed for all infants with isolated SUA.