title: The impact of gestational age on the sonographic detection of aneuploidy.
abstract: OBJECTIVE
  The purpose of this study was to identify the influence of gestational age on the detection of sonographic markers of aneuploidy.
  
  
  METHODS
  Using a retrospective chart review, cases of trisomy 13, 18, and 21 with fetal ultrasounds between 14 1/7 and 36 4/7 weeks' gestation were identified. Sonographic markers were subdivided into major abnormalities and "soft" sonographic markers: nuchal thickening > or = 5 mm, humerus or femur length <10th percentile, intracardiac echogenic focus, echogenic bowel, pyelectasis > or = 4 mm, and choroid plexus cysts. Markers were stratified by karyotype and gestational age.
  
  
  RESULTS
  Fifteen fetuses with trisomy 13, 32 with trisomy 18, and 49 with trisomy 21 were identified. There was no difference in the prevalence of ultrasound markers by gestational age (P = .40). Soft markers were more common in the second trimester of pregnancy (P = .006) with a trend toward increased prevalence of major anomalies with advancing gestation (P = .22).
  
  
  CONCLUSIONS
  Although sonographic markers change with gestational age, these markers are present throughout gestation and can provide clinically useful information to guide patient counseling.
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, The University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA. picklesimer@med.unc.edu
authors.forename: Amy H
authors.initials: AH
authors.lastname: Picklesimer
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Moise
authors.forename: Honor M
authors.initials: HM
authors.lastname: Wolfe
mesh_terms: D000328:Adult; D002882:Chromosomes, Human, Pair 13; D002887:Chromosomes, Human, Pair 18; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D012189:Retrospective Studies; D014314:Trisomy / Q000175:diagnosis*; D016216:Ultrasonography, Prenatal