P11.06: Invasive diagnosis of fetal aneuploidies after age-alone screening and 11 + 0-13 + 6wks screening in an Italian referral fetal medicine center

Abstract

Despite the largely demonstrated effectiveness of risk assessment for trisomy 21 by NT and maternal biochemistry, many obstetricians, suggest 1st trimester screening only in women aged < 35 while for older women recommend directly invasive diagnosis. In this study we analyze the effectiveness of this policy. In women < 35, invasive procedures are performed in our center, only if risk after screening is > 1/300. All women ≥ 35yo booking invasive procedure at the beginning of their pregnancy, are counseled about their possibility to undergo 1st trimester screening. In our first year experience 507 invasive procedures were performed and 42 aneuploidies were detected. Of the 412 women aged ≥ 35yo, 240 declined 1st trimester screening. The mean age of this group was 38,4.2 procedures were excluded as performed for known parental aneuploidies. In this group, were detected 13 chromosomal abnormalities. The indication of invasive testing of the 172 women aged ≥ 35yo that underwent NT screening, was maternal anxiety or high risk for aneuploidies. The mean age of this group was 37,9.2 women were excluded for known parental aneuploidies. 11 aneuploidies were detected. All 11 had increased risk for aneuploidies after the 1st trimester screening. The policy of performing invasive procedures in all women aged ≥ 35yo did not detect any chromosomal abnormality, in our series, that would not be identified after 1st trimester screening. On the contrary, the much higher false positive rate of the age-alone screening adds just increased collateral damage, high cost/benefit ratio to the national health system, precious time consuming investigations for obstetrician/geneticists.