Single Umbilical Artery and Its Associated Findings

OBJECTIVE: To estimate whether the presence of a single umbilical artery is associated with intrauterine growth restriction (IUGR), fetal demise, or major congenital anomalies. METHODS: We performed a retrospective cohort study of all consecutive singleton pregnancies undergoing routine anatomic survey between 1990 and 2007 at a major tertiary medical center. Two dedicated research nurses obtained complete pregnancy outcome data in an ongoing manner. Pregnancies with a diagnosis of single umbilical artery were compared with those with two umbilical arteries. The primary outcomes were IUGR (less than 10th percentile), renal, and cardiac anomalies. Multivariable logistic regression was used to refine the risk association between single umbilical artery and adverse pregnancy outcomes while adjusting for confounding effects. RESULTS: Of 72,373 pregnancies, 64,047 (88.5%) had pregnancy follow-up information and were available for this analysis. There were 392 cases of single umbilical artery (0.61%) diagnosed at anatomic survey; slightly lower than previously reported. Single umbilical artery as compared with double umbilical artery was associated with increased risk of renal anomalies (adjusted odds ratio [OR] 3.0, 95% confidence interval [CI] 1.9-4.9, P<.01) and cardiac anomalies (adjusted OR 20.3, 95% CI 13.5-30.4, P<.01). Single umbilical artery was also associated with an increased risk of IUGR (adjusted OR 2.1, 95% CI 1.6-2.7, P<.01), even after excluding all fetuses with known anomalies. CONCLUSION: Our data suggest an increased risk of IUGR when the diagnosis of single umbilical artery is made, making a clinical recommendation for serial growth assessments in the setting of single umbilical artery reasonable. (Obstet Gynecol 2010;115:930-4)