title: Increased nuchal translucency in the presence of normal chromosomes:  what's next?
abstract: OBJECTIVE
  First trimester screening is presently offered to all pregnant women as a means of prenatal screening for Down syndrome, trisomy 18, and trisomy 13. Nuchal translucency measurement is a fundamental component of the screening protocol. A woman whose fetus' nuchal translucency is greater than the 95th percentile is also at increased risk for a multiplicity of other adverse pregnancy and pediatric outcomes, and as a consequence, counseling of patients about their testing options and range of pregnancy outcomes has become complex and difficult.
  
  
  RESULTS
  The increased risk for chromosome abnormalities, congenital heart malformations, and pregnancy loss in the presence of an increased nuchal translucency is well documented. What has not been clearly defined is the incidence of other genetic syndromes, congenital defects, and adverse pregnancy and pediatric outcomes in the presence of increased nuchal translucency. Currently, Noonan syndrome is the only molecular genetic condition that has been shown to have a clear association with the finding of increased nuchal translucency in the first trimester.
  
  
  CONCLUSIONS
  This article reviews the current literature on outcomes in pregnancies with an increased nuchal translucency and a normal karyotype. We summarize the range of outcomes detected in the first trimester with recommendations for further prenatal testing and counseling of patients.
authors.affiliation: Northwestern Reproductive Genetics, Chicago, Illinois, USA. christina.alamillo@ymail.com
authors.forename: Christina M L
authors.initials: CM
authors.lastname: Alamillo
authors.forename: Morris
authors.initials: M
authors.lastname: Fiddler
authors.forename: Eugene
authors.initials: E
authors.lastname: Pergament
mesh_terms: D025063:Chromosome Disorders / Q000000981:diagnostic imaging; D000013:Congenital Abnormalities / Q000000981:diagnostic imaging*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005817:Genetic Counseling / Q000379:methods; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging; D006801:Humans; D059785:Karyotype; D009634:Noonan Syndrome / Q000000981:diagnostic imaging*; D048208:Nuchal Translucency Measurement / Q000379:methods; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis / Q000379:methods*