Characteristics and outcome of fetal nuchal translucency above 3.5 mm in the fi rst trimester

Abstract

Objective: To describe the natural history of fetuses with a nuchal translucency (NT) above 3.5 mm when crown-rump length measures between 45 and 84 mm. Methods: We performed a retrospective cohort study of fetuses with fi rst trimester NT above 3.5 mm between January 2013 and March 2017. Results: A total of 75 cases with NT above 3.5 mm in the fi rst trimester were identifi ed. 3 cases were excluded (lost to follow-up), so that 72 cases were included. There were additional fi rst trimester markers of aneuploidy in 16 cases and 5 cases of major structural abnormalities diagnosed in the fi rst trimester ultrasound. 2 cases declined invasive testing. The karyotype was abnormal in 30 cases (43%), including 17 cases of trisomy 21. There were 25 terminations of pregnancy (34.7%), 11 fetal deaths (15.3%) and 36 livebirths (50%). The 36 live-born infants were followed. In this group 3 cases of trisomy 21, 1 case of unilateral hypoplasia of orbicularis oris, 1 Noonan-like syndrome, 1 case of 8p23.1 duplication (benign variant) and 1 case of lower limb lymphedema were observed. Conclusion: The prognosis of fetal NT above 3.5 mm in the fi rst trimester is poor when associated with karyotype abnormalities or structural abnormalities but is substantially better if neither of these conditions is observed.

Outcome of pregnancies with first‐trimester increased nuchal translucency and cystic hygroma in a tertiary maternity hospital in United Arab Emirates

“…The risk of adverse pregnancy outcome among 59 euploid fetuses also increased with increasing NT thickness. These findings are similar to those of other studies 18,19 . In our study, 16.6% of euploid fetuses in the NT 95th centile −2.9 mm group had a structural defect detected antenatally.…”

“…These findings are similar to those of other studies. 18,19 In our study, 16.6% of euploid fetuses in the NT 95th centile −2.9 mm group had a structural defect detected antenatally. In the NT ≥3 mm group, 13.5% of euploid fetuses had a structural defect or syndrome detected antenatally, whereas one case was detected postnatally.…”

“…Yoshida et al observed chromosomal abnormalities in 19% of 58 cases with NT ≥3 mm 18 . In 2019, Lourenço et al reported abnormal karyotype in 43% of 72 cases with NT ≥3 mm 19 . Several studies have shown that adverse pregnancy outcomes become more likely with increasing NT thickness, even with a normal karyotype 17,20 .…”

“…Souka et al conducted a retrospective study of 1320 euploid pregnancies with NT ≥3.5 mm, and reported 68 (5.15%) spontaneous abortions or intrauterine deaths, 18 (1.36%) neonatal and infant deaths, and 154 (11.67%) TOPs 8 . Fetal structural anomalies are reported to be more strongly associated with increased NT 1,17–23 . Bilardo reported that 13% of euploid fetuses had a structural abnormality and cardiac defects were the most common 17 .…”