Prenatal diagnosis of persistent right umbilical vein - Incidence and clinical impact. A prospective study.

Background: Persistent right umbilical vein (PRUV) is usually an isolated finding but it may be accompanied by other fetal malformations.

Aims: We aimed to determine the incidence of prenatally diagnosed PRUV in a referral population, assess the neonatal outcome and discuss the findings together with those from previous publications.

Materials And Methods: A total of 2360 women with low-risk singleton pregnancies were examined in the second and third trimesters. A transabdominal convex volume transducer was used. B-mode was applied in each patient. Scanning of the venous system included imaging of the target vessels with two-dimensional colour Doppler mapping. The diagnosis of PRUV was made in a transverse section of the fetal abdomen. Three-dimensional ultrasounds were performed as necessary, when anomalous cases were encountered.

Results: The incidence of PRUV in our population was 12/2360 = 0.5%, and it was higher than in other retrospective studies. In 75% (n = 9), PRUV was an isolated finding where delivery was uneventful and the postnatal outcome was favourable. In two cases PRUV was accompanied by omphalocele, and in one case by tetralogy of Fallot and single umbilical artery.

Conclusions: PRUV is an uncommon prenatal finding. Screening for this anomaly can be easily performed in all pregnant patients. A diagnosis of PRUV should be followed by a thorough fetal morphology scan in order to exclude any other malformations, especially those of the cardiovascular system.