Impact of Increased Nuchal Translucency Values on Pregnancy Outcomes: A Tertiary Center Experience

Outcomes of pregnancies with varying levels of nuchal translucency measurements: A population-based retrospective study in Ontario, Canada

INTRODUCTION

Nuchal translucency prenatal ultrasound is widely used to screen for chromosomal abnormalities. An elevated nuchal translucency has been associated with adverse outcomes such as pregnancy loss; however, extant studies investigating these associations have had important limitations, including selection bias. This study aimed to investigate the association between nuchal translucency measurements and pregnancy outcome, specifically, a composite of pregnancy loss, termination, stillbirth, or neonatal death.

MATERIAL AND METHODS

This was a population-based retrospective cohort study conducted with data from the prescribed perinatal registry in Ontario, Canada, Better Outcomes Registry & Network. All singleton pregnancies with an estimated date of delivery from September 1, 2016, to March 31, 2021, and multiple marker screening including a nuchal translucency were included. Pregnancies with measurements 2.0- < 2.5 mm, 2.5- < 3.0 mm, 3.0- < 3.5 mm, 3.5- < 5.0 mm, 5.0- < 6.5 mm, and ≥6.5 mm were compared to a reference group with measurements <2.0 mm. We used multivariable modified Poisson regression models with robust variance estimation to estimate associations between nuchal translucency measurement and pregnancy outcome, with adjustment for age at estimated date of delivery and gestational age at screening.

RESULTS

There were 414 268 singleton pregnancies included in the study. The risk of pregnancy loss, termination, stillbirth, or neonatal death increased with increasing levels of nuchal translucency measurements, with an adjusted risk ratio (aRR) of 11.9 (95% confidence interval (CI) 9.9, 14.3) in the group with measurements 3.5- < 5.0 mm. When pregnancies with diagnosed chromosomal abnormalities were excluded, this association remained strong, with an aRR of 6.4 (95% CI 4.8, 8.5). Among pregnancies with a live birth, those with a higher nuchal translucency measurement (>5.0 mm vs. <2.0 mm) were also at increased risk of adverse perinatal outcomes such as admission to the neonatal intensive care unit and APGAR score <7.

CONCLUSIONS

In this population-based study using robust methods to reduce the risk of selection bias, we found that pregnancies with increased nuchal translucency measurements are less likely to result in a live birth, even with the exclusion of chromosomal abnormalities. Pregnancies with increased nuchal translucency measurements that resulted in a live birth may also be at increased risk of adverse perinatal outcomes.

Nuchal Translucency and Congenital Heart Defects

Nuchal translucency comprises a temporary accumulation of fluid in the subcutaneous tissue on the back of a fetus's neck, which accompanies the crown-rump length and is observed through an ultrasound performed between 11 and 13 weeks + 6 days gestation. Nuchal translucency is considered to be above normal when values are higher than the 95th/99th percentile or equal to or higher than 2.5/3.5 mm. The first connection between increased nuchal translucency and the presence of congenital heart defects is described in the study of Hyett et al., who observed that they are directly proportional. Since that time, several studies have been conducted to understand if nuchal translucency measurements can be used for congenital heart defect screening in euploid fetuses. However, there is great variability in the estimated nuchal translucency cutoff values for congenital heart defect detection. The purpose of this review was to understand how increased nuchal translucency values and congenital heart defects are related and to identify which of these defects are more frequently associated with an increase in these values.

Perinatal Outcomes in Foetuses with Increased Nuchal Translucency and Normal Karyotype: A Retrospective Cohort Study from the United Arab Emirates

This retrospective case-controlled study analysed the outcome of pregnancies with first-trimester enlarged nuchal translucency (NT) and a normal karyotype. A total of 479 pregnancies with first-trimester NT measurements were grouped as control (370 cases; normal NT) and study (109 cases; enlarged NT, ≥95th percentile; with normal karyotype). Adverse outcomes included miscarriage, intrauterine foetal death, termination of pregnancy, neonatal death, and structural/chromosomal/genetic abnormalities. The study was conducted between June 2016 and June 2022 at the Foetal Maternal Unit of Kanad Hospital, UAE. Overall, the live birth rate in the study group was significantly lower (74.3%) compared to the control (94.1%, p < 0.001). All pregnancy outcomes of this group significantly differed compared to the control. The observed miscarriage level was 9.2% (vs. 1.1%, p < 0.001), intrauterine foetal death was 2.8% (vs. 0%, p = 0.001), spontaneous preterm birthwas 11% (vs. 4.9%, p = 0.020), and termination of pregnancy was 3.7% (vs. 0%, p < 0.001). The presence of foetal abnormalities was also significantly higher in the enlarged NT group at 21% (vs. 3.3%, p < 0.001). Results indicate that enlarged NT is associated with adverse pregnancy outcomes even when the karyotype is normal. Based on these results, a comprehensive review of the guidelines for counselling and managing pregnancies with enlarged NT and a normal karyotype is recommended.

Does isolated nuchal translucency from 2.5 to 2.9 mm increase the risk of fetal chromosome disease?

Increased fetal nuchal translucency (NT) is a common ultrasonic manifestation during pregnancy. Many studies have confirmed that NT ≥ 3 mm is a high risk factor for adverse pregnancy outcome. However, when NT is between 2.5 and 2.9 mm, will it increase the risk of fetal chromosome abnormalities and other diseases? What is the most appropriate method for prenatal chromosome evaluation? At present, it has not been widely reported in the literature, and the conclusion is also controversial. This prospective cohort study included fetal samples from women who underwent amniocentesis from 2017 to 2020. The samples of the experimental group were fetuses with NT ≥ 2.5 mm at 11 to 13 + 6 weeks of gestation, with or without ultrasonographic anomaly. The control group contained fetal NT < 2.5 mm without ultrasonographic anomalies. All amniotic fluid samples were tested by copy number variants sequencing. In 262 fetal samples with isolated NT from 2.5 to 2.9 mm, the detection rate of aneuploidy was 3.4% (9/262), and the risk of aneuploidy was significantly higher than that of the control group (1.4%, 32/2331) (relative risk 2.5, 95% CI 1.2-5.2). The detection rates of other pathogenic/likely pathogenic copy number variants in the two groups were 0.8% (2/262) and 1.3% (31/2331), respectively, which was not statistically significant (relative risk 0.6, 95% CI 0.1-2.4). Our results showed that isolated NT from 2.5 to 2.9 mm increased the risk of fetal chromosome aneuploidy. Therefore, noninvasive prenatal screening is recommended as the first choice for prenatal chromosome evaluation in this population.

Extending the prenatal Noonan's phenotype by review of ultrasound and autopsy data

OBJECTIVES

The antenatal phenotypic spectrum of Noonan Syndrome (NS) requires better characterization.

METHODS

This multicenter retrospective observational included 16 fetuses with molecularly confirmed NS admitted for fetopathological examination between 2009 and 2016.

RESULTS

Among 12 pathogenic variants (PV) in PTPN11 (80%), 5 (42%) fell between position c.179 and c.182. Ultrasound showed increased nuchal translucency (n=13/16, 93%), increased nuchal fold after 15 weeks of gestation (n=12/16, 75%), pleural effusions (n=11/16, 69%), polyhydramnios (n=9/16, 56%), hydrops (n=7/16, 44%), cardiovascular (n=6/16, 38%) and cerebral (n=4/16, 25%) anomalies. Fetopathological examination found dysmorphic features in all cases, cardiovascular anomalies (n=12/15, 80%), pulmonary hypoplasia (n=10/15, 67%), effusions (n=7/15, 47%) and neuropathological anomalies (n=5/15, 33%). Hydrops was significantly (p=0.02) more frequent in the four fetuses with RIT1, NRAS and RAF1 PV versus the 12 fetuses with PTPN11 PV.

CONCLUSIONS

Increased nuchal translucency and nuchal fold is common in NS. NS antenatal phenotype showed high in utero fetal death, hydrops, prenatal pleural effusion and pulmonary hypoplasia, although the inclusion of only deceased fetuses will have selected more severe phenotypes. Non-specific cardiovascular and neurological abnormalities should be added to NS antenatal phenotype. Next generation sequencing will help detect more genotypes, clarifying the prenatal phenotype and identifying genotype-phenotype correlations. This article is protected by copyright. All rights reserved.

The diagnostic value of the early extended fetal heart examination at 13 to 14 weeks gestational age in a high-risk population

BACKGROUND

Congenital heart disease (CHD) is the most common congenital malformation that affects high-risk populations. A more definite heart diagnosis in the first trimester should be provided to guide clinical treatment. The study aim was to evaluate the diagnostic precision of the early extended fetal heart examination (EFHE) that includes abdominal situs view, four-chamber view (4CV), left ventricular outflow tract view (LVOT), right ventricular outflow tract view (RVOT), 3-vessel and tracheal view (3VT), ductal arch view, and the aortic arch view in the detection of CHD at the gestational age (GA) 13 to 14 weeks in a population with high risks.

METHODS

This study was a diagnostic test study. EFHE was performed by transabdominal sonography in women at GA 13 to 14 weeks with singleton pregnancies who were at high risk for CHD. The risk of CHD was determined by family history of CHD, rubella infection, metabolic disorders, exposure to teratogens, conception by in-vitro fertilization (IVF), increased nuchal translucency (NT) thickness, abnormal obstetric ultrasound, etc. The operator had more than 5 years of experience in first-trimester scans and fetal echocardiography. Early scans were compared with a fetal echocardiography in the second trimester (16-24 weeks).

RESULTS

EFHE was performed, and the pregnancy outcomes were obtained in 234 single pregnancies with a high risk of CHD. The average crown-rump length (CRL) was (76.17±7.09) mm. CHD was diagnosed in 43 cases by EFHE; 10 of these cases were misdiagnosed, and 2 cases were missed. Four cases were inconsistent in the main diagnosis of CHD. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and kappa coefficient (Ko) value of EFHE in diagnosing CHD by type and severity was 84.6% [95% confidence interval (CI), 69.5-94.1%], 96.9% (95% CI, 93.4-98.9%), 84.6% (95% CI, 69.5-94.1%), 96.9% (95% CI, 93.4-98.9%), and 0.82 (P<0.001), respectively.

CONCLUSIONS

EFHE can work as a diagnose examination for most major CHD cases at GA 13 to 14 weeks by an experienced operator; Therefore, this diagnostic system for fetal CHD may be applied in the first trimester. The study has been registered in the Chinese Clinical Trial Registry (www.chictr.org.cn). The registration number is ChiCTR2000038451.

Analysis of copy number variation by sequencing in fetuses with nuchal translucency thickening

Objective

Copy number variation sequencing (CNV‐seq) technique was used to analyze the genetic etiology of fetuses with increased nuchal translucency (NT).

Methods

A total of 139 women with gestational 11‐14 weeks whose fetuses were detected with increased NT (NT ≥ 2.5 mm) in our hospital from July 2016 to December 2018 were selected. Fetal specimens were performed for karyotyping analysis and CNV sequencing.

Results

According to the nuchal translucency thickness, 2.5‐3.4, 3.5‐4.4, 4.5‐5.4, and more than 5.5 mm, the rates of chromosomal abnormalities were 22.8% (13/57), 30.8% (12/39), 42.1% (8/19), and 62.5% (15/24), respectively. There was significant difference among the incidences of chromosomal abnormalities in four groups (χ² = 37.69, P < .01) and the incidences increased with fetal NT thickness. Among 139 cases, there were 36 cases (25.9%) with abnormal chromosome karyotypes. Meanwhile, there were 45 cases (32.3%) with abnormal CNV. In the 12 cases with abnormal CNV and normal chromosome karyotypes, there were 2 cases of pathogenic CNV, 7 cases of CNV with unknown clinical significance, and 3 cases of possibly benign CNV. There was no significant difference in CNV between pregnant women in advanced maternal age and those in normal maternal age (χ² = 1.389, P = .239). In the fetus who showed abnormalities in NT and ultrasonography (χ² = 5.13, P < .05) and the fetus aborted (χ² = 113.19, P < .05), the abnormal rate of CNV was higher with statistically significant difference.

Conclusion

CNV‐seq combined karyotype analysis should be performed simultaneously in fetuses with increased NT, providing a basis for genetic counseling, which is of great significance for prenatal diagnosis.