The aim of our study was to analyze the distribution of biochemical markers (free-� hCG and PAPP-A) and nuchal translucency (NT) values and their deviation from expected median in our screening program. NT, free-� hCG and PAPP-A values were measured in first trimester sera of 1313 singleton pregnant women. The age (mean �standard deviation) of pregnant women at the time of screening was 28.94�4.95 years and the gestational age was 87.66�4.74 days. The value of NT (median�standard error of mean) was 0.87�0.01 multiple of median corrected (MoMc), of free-b hCG was 1.07�0.02 MoMc and of PAPP-A was 1.06�0.01 MoMc. Since the huge majority of pregnant women carried a healthy fetus it was assumed that the median value of measurements was equal to 1 MoMc and the deviation from median was equal to null. Our results showed that the greatest deviation from the expected median (-0.13 MoMc) was recorded for the NT measurement while the deviation for the free-� hCG and PAPP-A values was 0.07 respectively 0.06. In conclusion the main disturbing factor in calculating the aneuploidy risk was the measurement of NT. A systematic audit of laboratory and ultrasound measurement is necessary.
P01.19: First-trimester screening by nuchal translucency measurement in an unselected Lebanese population
