title: Fetal thickened nuchal soft tissues may first appear in the second trimester in Down syndrome.
abstract: OBJECTIVE
  To describe a series of cases of late-onset fetal nuchal translucency in Down syndrome.
  
  
  METHODS
  In our practice area, most pregnant women usually undergo 3 different sonographic examinations: a fetal nuchal translucency examination in the 1st trimester and 2 detailed surveys of all fetal organs in the early 2nd trimester and in midpregnancy.
  
  
  RESULTS
  During the study period (2003-2008), we detected 11 fetuses with new appearance of severe thickened nuchal soft tissues (>or=6 mm) at 14-16 weeks' gestation after a normal nuchal screening in the 1st trimester. All of these fetuses had trisomy 21. Associated structural anomalies were observed in 10/11 of the cases. In addition, there were 12 fetuses with new appearance of thickened nuchal soft tissues (<4 mm); all these fetuses had a normal karyotype and were normal at delivery.
  
  
  CONCLUSIONS
  Obstetricians should be aware that a nuchal abnormality may first appear only at 14-16 weeks' gestation. Fetal karyotyping is advocated in these cases because of the high probability of Down syndrome.
authors.affiliation: Department of Obstetrics and Gynecology, Rambam Medical Center and Faculty of Medicine, Technion-Israel Institute of Technology, 1 Efron St., Haifa 31096, Israel.
authors.forename: Etan Z
authors.initials: EZ
authors.lastname: Zimmer
authors.forename: Shraga
authors.initials: S
authors.lastname: Blazer
authors.forename: Shai
authors.initials: S
authors.lastname: Linn
authors.forename: Moshe
authors.initials: M
authors.lastname: Bronshtein
mesh_terms: D003937:Diagnosis, Differential; D004314:Down Syndrome / Q000000981:diagnostic imaging* / Q000196:embryology; D019160:Endosonography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D009333:Neck / Q000000981:diagnostic imaging* / Q000196:embryology; D048208:Nuchal Translucency Measurement / Q000379:methods*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D015203:Reproducibility of Results