Distribution of Biochemical and Ultrasound Markers Values in the First Trimester Screening Program in Timisoara

Abstract

The aim of our study was to analyze the distribution of biochemical markers (free-â hCG and PAPP-A) and nuchal translucency (NT) values and their deviation from expected median in our screening program. NT, free-â 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-β 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-â 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.

Influence of Weight of Pregnant Women on First Trimester Biochemical Markers Values

“…Accurate evaluation of aneuploidy risk by combined first trimester screening test implies the elimination of the effect of disturbing factors (smoking, ethnicity, method of conception, presence of diabetes or the weight of the pregnant woman) on biochemical markers concentration [1,7,8]. We herein analyze the effect of weight of pregnant women on PAPP-A and free β hCG seric concentration, and the availability of the risk calculation software to correct this effect.…”

“…The most worldwide-promoted fetal aneuploidies screening program is the first trimester combined test [1,2]. The combined screening test protocol was developed by Fetal Medicine Foundation and relies on the determination of the described ultrasound and biochemical markers [2].…”

“…Since the precision of risk evaluation depends on accuracy of corrected MoM values calculation, it is mandatory to appreciate the capability of the risk evaluation software to counterbalance the effect of factors other than the fetus which influence the MoMs [1,[7][8][9]. We found an inverse correlation between weight and biochemical markers concentration.…”

“…The biochemical markers included in the first trimester screening algorithm are free beta human chorionic gonadotropin hormone (free-β-hCG) and pregnancy associated plasma protein A (PAPP-A) [1]. Based on the age of pregnant women, the values of first trimester biochemical and ultrasound markers (nuchal translucency, presence of nasal bone, Doppler evaluation) a risk of fetal aneuploidies could be calculated for each pregnancy [2].…”

“…Studies showed that concentrations of biochemical markers are influenced not only by the status of the fetus but by some features of the pregnant women too. Studies analyzed physical and behavioral features of pregnant women that influence the concentrations of biochemical markers: smoking status [1,7,8], weight, rhesus group and localization of placental insertion [9], ethnicity or mode of conceiving. In order to counterbalance the influence of the factors described above on concentrations of biochemical markers values, compensatory mathematical algorithms were developed.…”