Significance of a single umbilical artery in fetuses with central nervous system malformations.

To determine whether the presence of a single umbilical artery (SUA) is useful information for evaluating fetuses with known central nervous system (CNS) malformations, the present study reviewed 107 consecutive cases of fetal CNS malformations (hydrocephalus, meningomyelocele, Dandy‐Walker malformation, and holoprosencephaly) identified by prenatal sonography. Of the 107 fetuses studied, 20 (18%) had a SUA noted at the time of delivery or autopsy and 87 (81.3%) had two umbilical arteries. Of the 20 fetuses with a SUA, six were prospectively recognized on sonography, six were identified retrospectively, and eight could not be evaluated due to oligohydramnios or technical factors. All 20 fetuses with a SUA had extra‐CNS anomalies and 8 of 15 (53%) fetuses tested had chromosomal abnormalities. These rates were significantly higher (P less than .05) than observed in 87 fetuses with two umbilical arteries who had extra‐CNS anomalies in 35 cases (39%) and chromosomal abnormalities in 11 of 45 (24%) cases tested. We conclude that identification of a SUA in combination with a CNS anomaly should suggest the presence of additional extra‐CNS anomalies and is an indication for chromosomal analysis.