title: Role of ultrasound for Down syndrome screening in advanced maternal age.
abstract: OBJECTIVE
  To determine the sensitivity and false-positive rate of Down syndrome screening by use of maternal serum screen and the genetic sonogram in women > or =35 years of age.
  
  
  METHODS
  We searched our perinatal databases retrospectively from January 1992 to January 2000 for the following criteria: known Down syndrome fetus or newborn, advanced maternal age, and genetic sonogram from 14-24 weeks' gestation. The a priori maternal age or maternal serum screen risk was modified by likelihood ratios for ultrasound markers. Without markers the risk was reduced by 50%. The cut-off was 1:270.
  
  
  RESULTS
  Age and maternal serum screen had a sensitivity of 90.5% and a false-positive rate of 27.1%. Age and ultrasound had a 95.2% sensitivity and 43.5% false-positive rate, whereas the combination of age, maternal serum screen, and ultrasound had a 97.6% sensitivity and a 22.0% false-positive rate.
  
  
  CONCLUSIONS
  The combination of age, maternal serum screen, and ultrasound improves the sensitivity for Down syndrome detection in the advanced maternal age population.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Connecticut Health Center, Farmington, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Egan
authors.forename: L
authors.initials: L
authors.lastname: Malakh
authors.forename: G W
authors.initials: GW
authors.lastname: Turner
authors.forename: G
authors.initials: G
authors.lastname: Markenson
authors.forename: J R
authors.initials: JR
authors.lastname: Wax
authors.forename: P A
authors.initials: PA
authors.lastname: Benn
mesh_terms: D000328:Adult; D000375:Aging / Q000097:blood; D004314:Down Syndrome / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000235:genetics; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D008423:Maternal Age; D008875:Middle Aged; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal