The clinical impact of the first‐trimester nuchal translucency between the 95th–99th percentiles

Abstract

Objectives To evaluate the clinical significance of nuchal translucency (NT) between the 95th–99th percentile in terms of typical and atypical chromosomal abnormalities (ACAs), associated fetal congenital defects and postnatal outcome. Methods A retrospective cohort study of fetuses with NT between the 95th–99th percentile. Data regarding the rate of associated fetal defects, genetic abnormalities and postnatal outcome were collected. Results A total of 306 cases of fetuses with an NT between the 95th–99th percentiles were included. The overall rate of genetic abnormalities was 12.1% (37/306). Chromosomal abnormalities were found in 10.1% (31/306) of cases and 2% were ACA (6/306). Within this group, two were pathogenic Copy Number Variants (CNVs) and four were single gene disorders. The overall rate of fetal congenital defects was 13.7% (42/306). All ACAs were found in fetuses with congenital defects. Postnatally, a new diagnosis of a single gene disorder was made in 0.85% of cases (2/236). Conclusions The presence of an NT between the 95th–99th percentiles carries a 10‐fold increased risk of fetal defects, representing an indication for referral for a detailed fetal anatomy evaluation. The risk of ACA is mainly related to the presence of fetal defects, irrespective of the combined test risk.

Associations between genomic aberrations, increased nuchal translucency, and pregnancy outcomes: a comprehensive analysis of 2,272 singleton pregnancies in women under 35

“…Firstly, it relied on retrospective data collection. Secondly, the incidence of structural defects in fetuses with NT measurements between 2.5–2.9 mm was higher than previously reported in the literature ( 7 , 17 ). This discrepancy may be attributed to the fact that some pregnant women opted for NIPT instead of invasive prenatal diagnosis, potentially influencing the observed incidence of structural defects.…”

“…Further underscoring this importance, our study found fetal congenital defects in 18.4% of fetuses with NT 2.5–2.9 mm. Fantasia et al ( 17 ) also recognized the significance of mild NT elevations (between the 95th and 99th percentiles), reporting rates of 12.1% for chromosomal abnormalities and 13.7% for congenital defects. However, it’s important to note that an NT of 3.0 mm does not directly correlate to the 95th percentile.…”

“…The presence of additional anomalies appears to increase the likelihood of identifying pathogenic/likely pathogenic CNVs. Additionally, Fantasia et al reported that ACA was exclusively observed in fetuses with congenital malformations ( 17 ). Some studies suggested that utilizing a dynamic cutoff value of 1.9 MoM or the 99th centile might enhance the screening efficiency for atypical chromosomal abnormalities ( 3 ).…”

The first trimester: The new focal point for prenatal screening and diagnosis

“…Despite showing a good performance of such a scan in their center, Pruthi and colleagues in Canada do not recommend implementing detailed first trimester anatomy scanning outside tertiary referral centers 10 . Research continues to bring new insights on the diagnostic ability of the early ultrasound scan: the fetal heart, 11 the central nervous system 12,13 skeletal dysplasias 14 and increased nuchal translucency 15 . Also, among the first trimester screening strategies for congenital anomalies discussed by Bardi et al., early anatomical assessment occupies a central role, from the most advanced to more traditional screening menus 7…”

“…10 Research continues to bring new insights on the diagnostic ability of the early ultrasound scan: the fetal heart, 11 the central nervous system 12,13 skeletal dysplasias 14 and increased nuchal translucency. 15 Also, among the first trimester screening strategies for congenital anomalies discussed by Bardi et al, early anatomical assessment occupies a central role, from the most advanced to more traditional screening menus. 7 One of the concerns with early fetal anatomy ultrasound, which can facilitate earlier terminations for fetal anomalies, is the potential loss of information from a detailed autopsy.…”