P058a: Pregnancy outcome and follow-up in fetuses with increased first trimester nuchal translucency

Abstract

The aim of this study was to examine the relationship between nuchal translucency (NT) measurements and outcome of pregnancy with special regard to fetuses with an enlarged nuchal translucency and a normal karyotype. In this multicenter historical prospective study, 18 experienced operators, members of Collège Français d'Echographie Foetale followed 729 fetuses with increased first trimester NT or cystic hygroma between 1985 and 2002. The NT cut-off was 3 mm for 13 operators, 2.5 mm for 4 operators and 95th centile for one operator. Complete follow-up was obtained in 93.3% of the cases. Data were collected via an internet database. Follow up time varied between 1 day and 6 months. Of those 729 fetuses, 170 (23.3%) were abnormal karyotypes. Forty-nine (6.7%) pregnancies were lost to follow-up. In the 680 (93.3%) pregnancies there were 48 (7.1%) spontaneous abortions or intrauterine deaths, 2 (0.3%) neonatal deaths, 224 (32.9%) terminations of pregnancy and 406 (59.7%) live births. In the 406 live births, 29 (7.1%) had abnormalities requiring medical or surgical treatment or leading to mental handicap. The chance of a livebirth with no defects in the group with NT of 3.0–3.4 mm was 77.0%, for those with NT of 3.5–3.9 mm it was 63.2%, for those with NT of 4.0–4.9 mm it was 46.9%, for those with NT of 5.0–5.9 mm it was 33.3%, for those with NT of > 6 mm it was 13.5%. Increased fetal NT is associated with chromosomal abnormalities and fetal defects. In our series the percentage of children born alive presenting anomalies was lower than 10%.