Persistent right umbilical vein

A persistent right umbilical vein (PRUV) is an uncommon vascular anomaly which is often detected in utero.

Epidemiology
The estimated prevalence is ~2 per 1000 births 1,2.

Pathology
In the normal situation, the right umbilical vein begins to obliterate in the ~4th week of gestation and disappears by the 7th week. With a PRUV, the right umbilical vein remains open and the left umbilical vein usually obliterates. A PRUV may also be supernumerary 6.

Location
A PRUV can be intra- or extrahepatic. The former is much commoner.

Associations
Numerous associations have been described (albeit at relatively low rates 3,9). They are commoner with the extrahepatic type and include:

single umbilical artery: especially in the extrahepatic type

chromosomal anomalies

trisomy 18

Noonan syndrome 8

situs anomalies

dextrocardia

congenital cardiac anomalies

congenital renal anomalies

congenital gastrointestinal anomalies

vertebral anomalies

Radiographic features
Ultrasound
It is usually detected in the 2nd to 3rd trimester. Assessment is usually made in the axial plane and color Doppler is often required. An intrahepatic persistent right umbilical vein may be seen as an umbilical vein abnormally connected to the right portal vein and the fetal gallbladder is positioned medial to the PRUV.

Treatment and prognosis
When additional anomalies are ruled out, a PRUV in isolation carries a generally favorable outcome 1,9.

Practical points
If a persistent right umbilical vein is detected, a careful sonographic anatomical survey is generally recommended to rule out more serious congenital malformations