Risk assessment of trisomy 21 by maternal age and fetal nuchal translucency thickness in 7,096 unselected pregnancies in Slovenia.
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.
Strah
Darija M
DM
Obs/Gyn Oupatient Clinic ZD Domzale, Slovenia. darija.strah@siol.net
Pohar
Maja
M
Gersak
Ksenija
K
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