Isolated single umbilical artery anomaly and the risk for congenital malformations: a meta-analysis

Single umbilical artery (SUA) is an associated finding in many chromosomal abnormalities and congenital malformations. However, SUAcan also be seen as an isolated finding. The extent of diagnostic investigation and follow-up needed in infants with SUA as an isolated finding has long been debated. In this study the authors examined this issue by an analysis of the published papers concerning SUA anomaly.

A meta-analysis of 37 studies related to SUA published over a 40-year period was performed. Eleven of 37 studies were considered group 1 because the diagnosis of SUA was made using specimens obtained from early abortuses, fetal deaths, or autopsies. The remaining 26 studies were considered group 2 because the diagnosis of SUA was made from examining placental and umbilical cord specimens obtained from live-born infants or by examination of the umbilicus soon after birth.

The mean (and 95% CI) SUA incidence was 2.13% (1.92%, 2.34%) in group 1, and 0.55% (0.44%, 0.66%) in group 2. The mean incidence of congenital malformation associated with SUA was 66.3% (67.7%, 70.8%) in group 1, and 27% (21.6%, 32.3%) in group 2; these differences were significant (P< .05). In 7 of 26 group 2 studies, additional urologic investigations were performed in 204 infants who had an isolated SUA anomaly. Thirty-three of these 204 infants (16.2%, 95% CI, 7.7%, 25.6%) had some form of renal anomaly, but in 18 of 33 (54.5%) the anomalies were minor or self limiting. A cost-versus-benefit analysis showed that 14 isolated SUA cases need to be investigated to detect one major renal malformation; however, the value of detecting them early remained unclear because most of the anomalies would be apparent with good pediatric follow-up.

When SUA is an isolated anomaly in an otherwise healthy infant, there is a slight increase in the risk for renal malformations. This association is of similar magnitude to the coexistence of another anomaly with the presence of one anomaly. Most renal anomalies in isolated SUA cases are minor and self limiting, and even major anomalies are no different from those that are diagnosed during routine pediatric follow-up in otherwise healthy infants. Therefore, unless additional risk factors for malformations exist, the current data do not justify extensive urologic radiographic investigations in asymptomatic newborns having an isolated SUA anomaly.