[First trimester screening for Down syndrome at Prima facie. A 6-year survey]

To evaluate the results of screening for trisomy 21 by the combined risk of first trimester (as defined by the decree of June 23, 2009) in the Prima facie structure.

Single center study involving all patients that were seen for first trimester screening at Prima facie with singleton living pregnancy, not obtained by embryo donation, between 1 January 2009 and 31 December 2014.

Eighteen thousand two hundred and fifty-one patients were included, of which underwent screening for trisomy 21 by the combined risk. One thousand and forty-six (6.1%) had a calculated risk higher than 1/250. Seventy-five were affected by trisomy 21, of whom 65 in the high risk group. The sensitivity and specificity of screening are 86.7% and 94.4%. The median nuchal translucency was 0.98 MoM.

Screening for trisomy 21 by calculating the combined risk of first trimester enabled to detect 86.7% of trisomy 21 with a false positive rate of 5.6%.