title: Isolated single umbilical artery: evaluating the risk of adverse pregnancy outcome.
abstract: OBJECTIVE
  To evaluate if isolated single umbilical artery (SUA) diagnosed on second-trimester ultrasound has an independent risk association with adverse pregnancy outcomes.
  
  
  METHODS
  We compared 136 singleton pregnancies with isolated SUA with 500 consecutive singleton pregnancies with a three-vessel cord (3 VC). Pregnancies complicated by chromosomal abnormalities and other congenital malformations were excluded. The rates of intrauterine growth restriction (IUGR) defined as birth weight less than the 3rd percentile, small for gestational age (SGA) fetuses, defined as a birth weight lower than the 10th percentile and the incidence of very preterm deliveries before 34 weeks of gestation were compared between the two groups. Multivariable logistic regression analysis was performed to evaluate the risk association between SUA and adverse pregnancy outcomes, while controlling for potential confounders.
  
  
  RESULTS
  Fetuses with isolated SUA had significantly lower birth weight (2942.5 ± 783.7 vs. 3243.7 ± 585.6 g, p = 0.002), and were delivered at an earlier gestational age (38.7 ± 3.4 vs. 39.5 ± 2.2 weeks, p < 0.001), when compared to fetuses with a 3 VC. Fetuses with isolated SUA were at higher risk for IUGR (15.4% vs. 1.8%, p < 0.001), SGA (20.6% vs. 4.4%, p < 0.001) and very preterm delivery (6.6% vs. 1.4%, p = 0.002). Using a multiple logistic regression model, isolated SUA was shown to be an independent risk factor for IUGR (adjusted OR = 11.3, 95% CI 4.8-25.6; p < 0.001) and very preterm delivery (adjusted OR = 5.0, 95% CI 1.8-13.8; p = 0.002).
  
  
  CONCLUSIONS
  The presence of isolated SUA is independently associated with an increased risk for IUGR, SGA and very preterm delivery.
authors.affiliation: Medical University of Vienna, Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-maternal Medicine, Austria. Electronic address: mariella.mailath-pokorny@meduniwien.ac.at.
authors.forename: Mariella
authors.initials: M
authors.lastname: Mailath-Pokorny
authors.affiliation: Medical University of Vienna, Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-maternal Medicine, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Worda
authors.affiliation: Medical University of Vienna, Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-maternal Medicine, Austria.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Schmid
authors.affiliation: Medical University of Vienna, Department of Obstetrics and Gynecology, Division of General Gynecology and Gynecologic Oncology, Austria.
authors.forename: Stephan
authors.initials: S
authors.lastname: Polterauer
authors.affiliation: Medical University of Vienna, Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-maternal Medicine, Austria.
authors.forename: Dieter
authors.initials: D
authors.lastname: Bettelheim
mesh_terms: D000328:Adult; D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging* / Q000209:etiology; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D047928:Premature Birth / Q000000981:diagnostic imaging* / Q000209:etiology; D012307:Risk Factors; D058529:Single Umbilical Artery / Q000000981:diagnostic imaging*; D016216:Ultrasonography, Prenatal; D014469:Umbilical Arteries / Q000002:abnormalities* / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: IUGR; Perinatal outcome; Preterm delivery; SGA; Single umbilical artery