title: Clinical impact of systematic genetic sonogram screening in a low-risk population.
abstract: OBJECTIVE
  To determine the clinical impact of a genetic sonogram (GS) on a population at low risk for trisomy 21 (T21).
  
  
  METHODS
  A GS evaluating common major and minor markers was created and prospectively applied to consecutive women at 15-20 weeks' gestation presenting for routine ultrasound and at low T21 risk. Prenatal diagnosis (PND) referral occurred if 1 major marker, 2 minor markers, major malformation or choroid plexus cysts (CPCs) were seen. Neonatal outcomes were determined by chart review for neonates born at our institution and by letter for those born elsewhere. Using an ultrasound database, a similar population was identified prior to study inception and the GS retrospectively applied. PND referrals in both periods were confirmed by chart review. The rates of isolated minor marker (IMM), positive GS and PND referrals were compared using chi2 analysis.
  
  
  RESULTS
  IMM detection was unchanged (43 of 434, 10.1%) in the study vs. (23 of 243, 9.5%) control group. Excluding CPCs, 6 of 18 (33.3%) subjects of vs. 2 of 28 (7.1%) controls with IMM were referred for prenatal diagnosis (p < 0.03). The frequency of positive GS was unchanged: 14 of 434 (3.2%) subjects vs. 5 of 243 (2.1%) controls.
  
  
  CONCLUSIONS
  Currently no prospectively studied, effective ultrasound models exist for screening low-risk populations at 15-20 weeks. A GS with clear criteria for counseling on an increased T21 risk decreased inappropriate referrals without increasing positive screens.
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Dartmouth Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756, USA. michele.lauria@hitchcock.org
authors.forename: Michele R
authors.initials: MR
authors.lastname: Lauria
authors.forename: Michele D
authors.initials: MD
authors.lastname: Branch
authors.forename: Valerie H
authors.initials: VH
authors.lastname: LaCroix
authors.forename: Robert D
authors.initials: RD
authors.lastname: Harris
authors.forename: Emily R
authors.initials: ER
authors.lastname: Baker
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004314:Down Syndrome / Q000000981:diagnostic imaging* / Q000453:epidemiology; D005260:Female; D020022:Genetic Predisposition to Disease; D019983:Guideline Adherence; D006801:Humans; D008403:Mass Screening; D009513:New Hampshire / Q000453:epidemiology; D017410:Practice Guidelines as Topic; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D015995:Prevalence; D011446:Prospective Studies; D012017:Referral and Consultation; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000706:statistics & numerical data*