Persistent intrahepatic right umbilical vein: a prenatal sonographic series without significant anomalies.

Umbilical venous anatomy variation is considered extremely rare. The intrahepatic persistent right umbilical vein represents one version in the spectrum of umbilical vein variations. Prior reports of a prenatally diagnosed persistent right umbilical vein suggest it is strongly associated with severe fetal anomalies including congenital heart disease and gastrointestinal malformations. Our experience contrasts with these findings. Nine cases of intrahepatic persistent right umbilical vein were identified via prenatal sonography between July 1992 and January 1994. The gestational ages of the fetuses ranged from 20 to 36 weeks. Targeted fetal surveys were performed in all nine fetuses and formal fetal echocardiograms were obtained in six. All nine infants have been delivered. In nine cases, the intrahepatic persistent right umbilical vein was an isolated observation with no abnormalities identified pre- or postnatally except one case of hypospadias. Formal fetal echocardiography was normal in all six of the fetuses studied. Given previous reports describing a high risk of congenital malformations in association with the presence of a persistent right umbilical vein, the sonographic finding of this anomaly should still prompt targeted fetal sonography and fetal echocardiography. However, our series indicates that this vascular variant may occur as an isolated abnormality and may not necessarily represent the ominous finding suggested previously.