title: Changes in nuchal translucency thickness in normal and abnormal karyotype fetuses.
abstract: OBJECTIVE
  To investigate the dynamic trend of the nuchal translucency thickness between fetuses with normal and abnormal karyotype.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Ospedale Microcitemico, Cagliari, Italy.
  
  
  METHODS
  A cohort of 305 first trimester fetuses.
  
  
  METHODS
  Fetuses with a nuchal translucency greater than or equal to the 95th centile were invited for a second nuchal translucency measurement. The finding of an 'increased or unchanged' or 'diminished' thickness was compared in fetuses with normal and abnormal karyotype.
  
  
  METHODS
  Nuchal translucency and karyotype. Median maternal age was 35 years (min 17, max 44) and median crown-rump length at first visit was 50 mm (min 38, max 80). A second nuchal translucency measurement was carried out in 292 fetuses, resulting in increased or unchanged values in 95 cases and decreased nuchal translucency in 197 cases. Two hundred and twenty-six (77.4%) fetuses had normal karyotype and 66 (22.6%) had abnormal karyotype (44 trisomies 21, 10 trisomies 18, 5 trisomies 13, 4 cases of 45 X0, 1 case of 47,XXY, 1 case of 47,XXX and 1 translocation). In the 66 chromosomally abnormal fetuses, the second nuchal translucency measurement was enlarged or unchanged in 37 (56%), and diminished in 29 (44%), while in the 226 normal fetuses the second nuchal translucency measurement was enlarged or unchanged in 58 cases (25%) and diminished in 168 (75%) (relative risk 2.6, 95% confidence interval 1.7-4.0).
  
  
  CONCLUSIONS
  In fetuses with abnormal karyotype, the second nuchal translucency measurement tends to be increased or unchanged, while in normal cases the size of nuchal translucency is generally reduced.
authors.affiliation: Department of Obstetrics and Gynecology, Prenatal and Preimplantation Genetic Diagnosis, Fetal Therapy, Ospedale Microcitemico, Cagliari, Italy.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Zoppi
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Ibba
authors.forename: Marcella
authors.initials: M
authors.lastname: Floris
authors.forename: Fabiola
authors.initials: F
authors.lastname: Manca
authors.forename: Carolina
authors.initials: C
authors.lastname: Axiana
authors.forename: Giovanni
authors.initials: G
authors.lastname: Monni
mesh_terms: D000293:Adolescent; D000328:Adult; D002869:Chromosome Aberrations; D025063:Chromosome Disorders / Q000000981:diagnostic imaging*; D018568:Crown-Rump Length; D004314:Down Syndrome / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007621:Karyotyping; D008423:Maternal Age; D009333:Neck / Q000000981:diagnostic imaging / Q000196:embryology*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D018566:Pregnancy, High-Risk; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000592:standards