Single umbilical artery: Prevalence and clinical significance in prenatal sonography

Objective: To estimate the prevalence of single umbilical artery (SUA) in an Iranian population and to determine the absent side and its association with malformations. Methods: We prospectively studied 3240 singleton pregnancies of 14 to 30 weeks of gestational age with USG. The absent side, pregnancy data, and the perinatal outcome were reviewed. Results: SUA occurred in 1.1% of pregnancies. The artery was absent on the left side in 27 (71.1%). Nine of those with SUA had malformations (24%) and there were three deaths. The average stage of pregnancy at which SUA was diagnosed was at 27 weeks and 2 days. 20 fetuses were male. Conclusion: The prevalence of SUA and associated anomalies in our population seems to be similar to that reported in other countries. Absence of the left artery was more common. Evaluating cord vessels at the 20 th week of pregnancy is valuable and fetuses with an isolated SUA will benefit from a more detailed assessment and USG monitoring