title: Twin pregnancies discordant for single umbilical artery.
abstract: OBJECTIVE
  To evaluate the perinatal outcomes in twin pregnancies discordant for single umbilical artery (SUA).
  
  
  METHODS
  This was a retrospective cohort study. Our database was searched for all cases of twin gestation and SUA from 1997-2009. We reviewed all the maternal and neonatal records and placental pathology reports. The outcomes of the SUA fetuses were compared to that of their co-twins with a 3-vessel cord (3VC). Paired t test and chi2 tests were used for statistical analyses.
  
  
  RESULTS
  We identified 29 cases of twin pregnancies discordant for SUA out of 60,989 ultrasound patients. There were no differences in the prevalence of coexisting anomalies (34% vs. 21%, p = 0.38) between the SUA fetus and the 3VC fetus. The SUA fetus was found to have significantly lower mean birth weight (1,784 +/- 765 g vs. 2,053 +/- 668 g, p = 0.001), 1-minute Apgar score (6.83 +/- 1.89 vs. 7.62 +/- 1.18, p = 0.037), and umbilical artery cord pH (7.27 +/- 0.06 vs. 7.31 +/- 0.07, p = 0.001). The SUA fetus was smaller 79% of the time (p < 0.0001). The SUA fetus achieved a significantly lower percentile (12.77% +/- 21.8 vs. 32.00% +/- 27.56, p = 0.002) when calculating the customized growth potential.
  
  
  CONCLUSIONS
  The fetus affected by an SUA in a twin gestation has impaired fetal growth and neonatal outcomes when compared to its 3VC counterpart.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas, USA. benjamin.byers@yahoo.com
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Byers
authors.forename: George R
authors.initials: GR
authors.lastname: Saade
authors.forename: Hassan M
authors.initials: HM
authors.lastname: Harirah
mesh_terms: D001724:Birth Weight; D002585:Cesarean Section; D015331:Cohort Studies; D004200:Diseases in Twins / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D005865:Gestational Age; D006801:Humans; D008297:Male; D010929:Placentation; D011247:Pregnancy; D059285:Pregnancy, Twin; D012189:Retrospective Studies; D058529:Single Umbilical Artery / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D016216:Ultrasonography, Prenatal