Outcomes of an isolated single umbilical artery in singleton pregnancy: a large study from the Middle East and Gulf region

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ObjectiveTo assess the frequency and accuracy of prenatal diagnosis of a single umbilical artery (SUA) and to compare the fetal and neonatal outcome of isolated SUA to that of a normal three-vessel umbilical cord in a population from the Middle East and Gulf region. Study designData were collected from 37,500 singleton pregnancies that were scheduled for antenatal care and delivered at Security Forces Hospital in Riyadh, Saudi Arabia, between May 2004 and December 2012. Comparisons between the groups were performed using a chi-square test or a Fisher exact test for the categorical variables, and Student's t test or Wilcoxon's rank-sum test were used for continuous variables. The Kappa statistic was used to study the agreement between the antenatal and final neonatal diagnosis of SUA. A univariable analysis was used to calculate the unadjusted and adjusted ORs and the 95% CIs expressing the relationship of the normal three-vessel umbilical cord, the isolated SUA, and each outcome. ResultsA total of 35,249 cases completed the study, including 35,026 cases with normal neonatal three-vessel umbilical cords (Group B). SUA was present in 223 (0.63%) neonates (0.45% isolated SUA (Group A) and 0.18% non-isolated SUA). The sensitivity, specificity, positive predictive value and negative predictive value of using prenatal ultrasound for the diagnosis of SUA were 90.58%, 99.9%, 98.5% and 99.94%, respectively. Neonatal anomaly was present in 2.6% of the fetuses with isolated SUA. A pregnancy with isolated SUA was more likely to be complicated with polyhydramnios (OR 3.32; CI 1.22–9.04), preterm delivery <34 weeks (OR 4.662; CI 2.346–9.195), birth weight <10th percentile (OR 2.1; CI 1.44–2.93), cesarean delivery for fetal distress (OR 2.72; CI 1.53–4.81), perinatal death (OR 3.31; CI 1.34–8.12), admission to NICU (OR 2.71; CI 1.87–3.91), and placental abnormalities (OR 3.25; CI 2.14–4.93; p value 0.0001) compared to a pregnancy with a fetal and neonatal three-vessel cord. ConclusionIsolated SUA is associated with anomalies at birth and with an increased risk of adverse pregnancy outcomes even in the absence of other anomalies. A pregnancy with this complication should receive close fetal monitoring for growth and fetal wellbeing.