[Contribution of Doppler ultrasound to the antenatal diagnosis of persistent right umbilical vein: case report].

We report a case of an isolated persistent right umbilical vein which was diagnosed on an ultrasound examination performed in the third trimester of pregnancy. This was made possible by the contribution of color flow Doppler and real-time ultrasound. Having isolated the anomaly no further fetal monitoring was instituted. Delivery was at term and the infant is doing well. Persistent right umbilical vein results from an anomaly of organogenesis. It represents the main intra abdominal anomaly of this vein. Its incidence is estimated at approximately 1 case for 500 antenatal ultrasound examinations. Ultrasonographic diagnosis is relatively easy and can be performed near the end of the first trimester. After insertion in the abdominal wall, the umbilical vein passes round the gallbladder from the right before connecting to the portal vein in the intra-hepatic form; right atrium, inferior vena cava, superior vena cava or iliac vein in extra-hepatic form. Diagnosis is affirmed by color flow Doppler, which emphasizes a continuity of blood flow between the extra and intra abdominal segment of the umbilical vein, and real-time ultrasound, which shows a venous blood flow. Prognosis depends essentially on the existence of congenital malformations, which are observed in 10 to 25% of cases. When isolated, persistent right umbilical vein is generally associated with favorable outcome and must be considered as a normal fetal anatomical variant.