Persistent right umbilical vein: an ominous prenatal finding?

The persistence of a right umbilical vein is an uncommon finding, with only a dozen cases reported since 1826. The persistent right umbilical vein may replace the normal left umbilical vein or be supernumerary. The anomaly is associated with numerous and occasionally lethal malformations. In this series, only three of six fetuses (and another two in the literature) had no associated anomalies. All the others had a variety of associated lesions ranging from minor to lethal. The appearance at ultrasound is easy to recognize: The intrahepatic portion of the umbilical vein is lateral to the gallbladder, and the portal vein curves toward the stomach, instead of parallel to it. Since the recognition of the persistent right umbilical vein is simple and does not require additional scanning (it is visible in the section used to measure the abdominal perimeter), the author suggests using it as an indicator for more in-depth scanning.