title: Umbilical vein anomaly in fetuses with Down syndrome.
abstract: OBJECTIVE
  To describe the prevalence of abnormal umbilical vein (UV) anatomy in fetuses with Down syndrome.
  
  
  METHODS
  This was a retrospective survey covering a 24-month period of fetuses with a genetic diagnosis of Down syndrome following a routine early second-trimester (12-16-week) detailed fetal anomaly scan at a single academic tertiary referral center. In our unit this exam includes fetal umbilicoportal venous system evaluation.
  
  
  RESULTS
  During the study period, 37 fetuses were diagnosed with Down syndrome and had a detailed early anatomy scan. In four (11%) the detailed early anomaly scan revealed that the UV was connected to the hepatic portion of the inferior vena cava (IVC) at a position lower than its usual site. Their average gestational age at diagnosis was 13 + 6 (range, 11 + 6 to 15 + 2) weeks. Three of the four fetuses had a nuchal translucency thickness of 3-4 mm. In one fetus there was an additional finding of significant tricuspid regurgitation and the one with normal nuchal translucency thickness had an atrioventricular septal defect (atrioventricular canal) and umbilical cord hernia. During the same period three of 2500 (0.12%) fetuses with normal karyotype demonstrated similar anomalous insertion of the UV into the IVC, creating a portocaval shunt which had normal ductus venosus-like Doppler flow in all three cases. The odds ratio for abnormal umbilicoportal venous system in fetuses with Down syndrome compared with the normal population was 107.4 (95% CI, 19.2-637.1).
  
  
  CONCLUSIONS
  Fetuses with Down syndrome demonstrate an increased prevalence of abnormal connection of the UV to the IVC.
authors.affiliation: Department of Obstetrics and Gynecology, The Chaim Sheba Medical Center, Tel Hashomer, affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. rachiron@post.tau.ac.il
authors.forename: R
authors.initials: R
authors.lastname: Achiron
authors.forename: L
authors.initials: L
authors.lastname: Gindes
authors.forename: Y
authors.initials: Y
authors.lastname: Gilboa
authors.forename: A
authors.initials: A
authors.lastname: Weissmann-Brenner
authors.forename: M
authors.initials: M
authors.lastname: Berkenstadt
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D004314:Down Syndrome / Q000000981:diagnostic imaging* / Q000196:embryology / Q000503:physiopathology; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D048208:Nuchal Translucency Measurement / Q000379:methods; D011169:Portal Vein / Q000002:abnormalities / Q000000981:diagnostic imaging; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D012189:Retrospective Studies; D014262:Tricuspid Valve Insufficiency / Q000151:congenital / Q000000981:diagnostic imaging; D016216:Ultrasonography, Prenatal / Q000379:methods; D014471:Umbilical Veins / Q000002:abnormalities / Q000000981:diagnostic imaging* / Q000503:physiopathology