title: Risk assessment of trisomy 21 by maternal age and fetal nuchal translucency thickness in 7,096 unselected pregnancies in Slovenia.
abstract: OBJECTIVE
  To evaluate the screening for trisomy 21 by maternal age and nuchal translucency in a low-risk population.
  
  
  METHODS
  Screening was performed in 7,096 singleton pregnancies. The estimated risk for trisomy 21, the detection rate (DR), false positive rate (FPR) and the cut-off nuchal translucency thickness to obtain a 5% FPR were calculated.
  
  
  RESULTS
  The median maternal age was 28.6 years. The estimated risk for trisomy 21 was 1 in 300 or greater in 2.4% (171 of 7,096) of all pregnancies and in 75% (9 of 12) of trisomy 21 pregnancies. The DR for all aneuploidies was 83.3%, and 75% for trisomy 21. The estimated FPR at risk 1 in 300 for the whole population in 2004 was 3.8%. It is predicted to remain below 4% at least until 2007; to achieve a 5% FPR in 2007 the risk limit 1 in 400 is proposed.
  
  
  CONCLUSIONS
  Screening for trisomy 21 in a low-risk population in Slovenia gives comparable results to those in other countries. The only result that varies is the percentage of screen positive patients at the risk limit 1 in 300. We believe the risk limit should be specifically estimated for each country based on its population distribution of maternal age.
authors.affiliation: Obs/Gyn Oupatient Clinic ZD Domzale, Slovenia. darija.strah@siol.net
authors.forename: Darija M
authors.initials: DM
authors.lastname: Strah
authors.forename: Maja
authors.initials: M
authors.lastname: Pohar
authors.forename: Ksenija
authors.initials: K
authors.lastname: Gersak
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005189:False Positive Reactions; D005260:Female; D005865:Gestational Age; D006801:Humans; D008423:Maternal Age; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D017524:Slovenia / Q000453:epidemiology