Increased nuchal translucency and congenital heart defects in a low-risk population

Diagnostic accuracy of ultrasound screening for fetal structural abnormalities during the first and second trimester of pregnancy in low-risk and unselected populations

BACKGROUND

Prenatal ultrasound is widely used to screen for structural anomalies before birth. While this is traditionally done in the second trimester, there is an increasing use of first-trimester ultrasound for early detection of lethal and certain severe structural anomalies.

OBJECTIVES

To evaluate the diagnostic accuracy of ultrasound in detecting fetal structural anomalies before 14 and 24 weeks' gestation in low-risk and unselected pregnant women and to compare the current two main prenatal screening approaches: a single second-trimester scan (single-stage screening) and a first- and second-trimester scan combined (two-stage screening) in terms of anomaly detection before 24 weeks' gestation.

SEARCH METHODS

We searched MEDLINE, EMBASE, Science Citation Index Expanded (Web of Science), Social Sciences Citation Index (Web of Science), Arts & Humanities Citation Index and Emerging Sources Citation Index (Web of Science) from 1 January 1997 to 22 July 2022. We limited our search to studies published after 1997 and excluded animal studies, reviews and case reports. No further restrictions were applied. We also screened reference lists and citing articles of each of the included studies.

SELECTION CRITERIA

Studies were eligible if they included low-risk or unselected pregnant women undergoing a first- and/or second-trimester fetal anomaly scan, conducted at 11 to 14 or 18 to 24 weeks' gestation, respectively. The reference standard was detection of anomalies at birth or postmortem.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook study selection, quality assessment (QUADAS-2), data extraction and evaluation of the certainty of evidence (GRADE approach). We used univariate random-effects logistic regression models for the meta-analysis of sensitivity and specificity.

MAIN RESULTS

Eighty-seven studies covering 7,057,859 fetuses (including 25,202 with structural anomalies) were included. No study was deemed low risk across all QUADAS-2 domains. Main methodological concerns included risk of bias in the reference standard domain and risk of partial verification. Applicability concerns were common in studies evaluating first-trimester scans and two-stage screening in terms of patient selection due to frequent recruitment from single tertiary centres without exclusion of referrals. We reported ultrasound accuracy for fetal structural anomalies overall, by severity, affected organ system and for 46 specific anomalies. Detection rates varied widely across categories, with the highest estimates of sensitivity for thoracic and abdominal wall anomalies and the lowest for gastrointestinal anomalies across all tests. The summary sensitivity of a first-trimester scan was 37.5% for detection of structural anomalies overall (95% confidence interval (CI) 31.1 to 44.3; low-certainty evidence) and 91.3% for lethal anomalies (95% CI 83.9 to 95.5; moderate-certainty evidence), with an overall specificity of 99.9% (95% CI 99.9 to 100; low-certainty evidence). Two-stage screening had a combined sensitivity of 83.8% (95% CI 74.7 to 90.1; low-certainty evidence), while single-stage screening had a sensitivity of 50.5% (95% CI 38.5 to 62.4; very low-certainty evidence). The specificity of two-stage screening was 99.9% (95% CI 99.7 to 100; low-certainty evidence) and for single-stage screening, it was 99.8% (95% CI 99.2 to 100; moderate-certainty evidence). Indirect comparisons suggested superiority of two-stage screening across all analyses regarding sensitivity, with no significant difference in specificity. However, the certainty of the evidence is very low due to the absence of direct comparisons.

AUTHORS' CONCLUSIONS

A first-trimester scan has the potential to detect lethal and certain severe anomalies with high accuracy before 14 weeks' gestation, despite its limited overall sensitivity. Conversely, two-stage screening shows high accuracy in detecting most fetal structural anomalies before 24 weeks' gestation with high sensitivity and specificity. In a hypothetical cohort of 100,000 fetuses, the first-trimester scan is expected to correctly identify 113 out of 124 fetuses with lethal anomalies (91.3%) and 665 out of 1776 fetuses with any anomaly (37.5%). However, 79 false-positive diagnoses are anticipated among 98,224 fetuses (0.08%). Two-stage screening is expected to correctly identify 1448 out of 1776 cases of structural anomalies overall (83.8%), with 118 false positives (0.1%). In contrast, single-stage screening is expected to correctly identify 896 out of 1776 cases before 24 weeks' gestation (50.5%), with 205 false-positive diagnoses (0.2%). This represents a difference of 592 fewer correct identifications and 88 more false positives compared to two-stage screening. However, it is crucial to acknowledge the uncertainty surrounding the additional benefits of two-stage versus single-stage screening, as there are no studies directly comparing them. Moreover, the evidence supporting the accuracy of first-trimester ultrasound and two-stage screening approaches primarily originates from studies conducted in single tertiary care facilities, which restricts the generalisability of the results of this meta-analysis to the broader population.

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.

Diagnosis of major heart defects by routine first-trimester ultrasound examination: association with increased nuchal translucency, tricuspid regurgitation and abnormal flow in ductus venosus

OBJECTIVE

To examine the association between fetal major heart defects and increased nuchal translucency thickness (NT), tricuspid regurgitation and abnormal flow in the ductus venosus in a large population of singleton pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation.

METHODS

This was a retrospective study of prospectively collected data from singleton pregnancies attending for a routine ultrasound scan at 11-13 weeks' gestation, which included examination of fetal anatomy, measurement of NT and assessment of blood flow across the tricuspid valve and in the ductus venosus, according to a standardized protocol. The incidence of fetal NT ≥ 95^th and ≥ 99^th percentiles, tricuspid regurgitation and reversed a-wave in the ductus venosus in fetuses with and those without a major heart defect was determined and the performance of each marker and their combination in the detection of major heart defects was calculated.

RESULTS

The study population of 93 209 pregnancies with no apparent chromosomal abnormality included 211 (0.23%) with a fetal major heart defect and 92 998 morphologically normal neonates. In 113 (53.6%) cases with a major heart defect, the diagnosis was made at the 11-13-week scan, in 82 (38.9%) at the 18-24-week scan, in 10 (4.7%) at the third-trimester scan and in six (2.8%) postnatally. At the 11-13-week scan, we diagnosed all cases of tricuspid or pulmonary atresia and polyvalvular dysplasia, > 90% of cases of hypoplastic left heart syndrome or atrioventricular septal defect, about 60% of complex heart defects and cases of left atrial isomerism (interrupted inferior vena cava with normal intracardiac anatomy), 30-40% of cases of tetralogy of Fallot and arch abnormalities, 25% of tricuspid valve abnormalities and about 15% of cases of transposition of the great arteries, but none of aortic or pulmonary stenosis or common arterial trunk. Fetal NT ≥ 95^th or ≥ 99^th percentile, tricuspid regurgitation or abnormal ductus venosus flow was observed in 77 (36.5%), 45 (21.3%), 61 (28.9%) and 58 (27.5%) fetuses with a major heart defect, respectively, and in 5678 (6.1%), 857 (0.9%), 1136 (1.2%) and 1644 (1.8%) of those without a heart defect. Any one of NT ≥ 95^th percentile, tricuspid regurgitation or abnormal flow in the ductus venosus was found in 117 (55.5%; 95% CI, 48.5-62.3%) fetuses with a heart defect and in 8166 (8.8%; 95% CI, 8.6-9.0%) of those without a heart defect. Any one of NT ≥ 99^th percentile or the other two markers was found in 99 (46.9%; 95% CI, 40.0-53.9%) fetuses with a heart defect and in 3517 (3.8%; 95% CI, 3.7-3.9%) of those without a heart defect.

CONCLUSION

At 11-13 weeks' gestation, measurement of fetal NT and assessment of flow across the tricuspid valve and in the ductus venosus can lead to early diagnosis of major heart defect. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal detection of congenital heart disease in a low risk population undergoing first and second trimester screening

OBJECTIVES

The prenatal detection rate of congenital heart disease (CHD) is low compared with other fetal malformations. Our aim was to evaluate the prenatal detection of CHD in Eastern Denmark.

METHODS

Fetuses and infants diagnosed with CHD in the period 01.01.2008-31.12.2010 were assessed regarding prenatal detection rate and accuracy, as well as correlation with nuchal translucency (NT) thickness.

RESULTS

Out of 86 121 infants, 831 were born with CHD (0.96%). The prenatal detection rate of 'all CHD' was 21.3%, of 'Major CHD' 47.4%. Full agreement between prenatal and postnatal/autopsy findings was found in 96% of prenatally detected diagnoses. An NT thickness >95(th) percentile was found in 15.0% fetuses with 'Major CHD'. Of 'Major CHDs' detected prenatally, 77% were picked up at the time of the malformation scan at weeks 18-21.

CONCLUSIONS

Nearly half of 'Major CHDs' were detected prenatally. The prenatal cardiac diagnoses showed a high degree of accuracy. Increased NT thickness as a screening tool for CHD performed moderately but is an important high risk group for specialist examination. A minority of the prenatally detected CHDs was identified because of extra scans performed in high risk pregnancies. © 2014 John Wiley & Sons, Ltd.

Nuchal translucency and major congenital heart defects in fetuses with normal karyotype: a meta-analysis

OBJECTIVE

To pool published data regarding the sensitivity and specificity of nuchal translucency (NT) in the diagnosis of major congenital heart defects (CHDs) in fetuses with normal karyotype.

METHODS

MEDLINE and Scopus searches using combinations of the terms 'nuchal' and 'cardiac*' were complemented by perusal of references of the retrieved articles and an additional automated search using the 'search for related articles' function on PubMed. Only fetuses with normal karyotype and major CHDs were analyzed. Weighted estimates were made and summary receiver-operating characteristics curves were constructed.

RESULTS

The analysis included 20 studies (205 232 fetuses; 537 cases with major CHDs). The pooled sensitivity and specificity of NT > 95(th) centile for diagnosis of major CHDs was 44.4% (95% CI, 39.5-49.5) and 94.5% (95% CI, 94.4-94.6), respectively. The pooled sensitivity and specificity of NT > 99(th) centile was 19.5% (95% CI, 15.9-23.5) and 99.1% (95% CI, 99.1-99.2), respectively. For the subgroup of studies in which NT was measured by Fetal Medicine Foundation-certified operators, the pooled sensitivity and specificity of NT > 95(th) centile was 45.6% (95% CI, 39.6-51.7) and 94.7% (95% CI, 94.6-94.9), respectively. The corresponding estimates for NT > 99(th) centile were 21.0% (95%CI, 16.5-26.1) and 99.2% (95% CI, 99.2-99.3). The pooled positive likelihood ratio for NT > 99(th) centile was 30.5 (95% CI, 24.3-38.6). There was high across-studies heterogeneity for most estimates.

CONCLUSION

Approximately 44% of chromosomally normal fetuses with CHDs have NT > 95(th) centile and 20% have NT > 99(th) centile. However, there is high heterogeneity across studies, which largely remains even in subgroup analyses of studies of apparently similar design, potentially indicating the presence of some residual unidentified bias.

Increased nuchal translucency and congenital heart disease

Sonographic assessment of fetal nuchal translucency (NT) thickness is the cornerstone of screening for chromosomal abnormality at 11-13(+6) weeks gestation. This marker was first recognized in pregnancies being karyotyped for advanced maternal age, but its underlying pathophysiology remains to be fully determined. Although increased NT is clearly associated with changes in both lymphatic and cardiac development, neither is an obvious causative agent. The association with cardiac defects has now being subjected to a significant amount of research, with a large body of evidence showing that this marker is also a screening tool for major cardiac defects - although it performs more modestly than for chromosomal abnormality. The field continues to change rapidly. Recent evidence that uses a combination of increased NT, tricuspid regurgitation and abnormal flow in the 'a' wave of the ductus venosus can provide an effective screening strategy to predict many major cardiac defects at this early stage of pregnancy.

Additional first-trimester ultrasound markers

The first trimester (11-13 +6 weeks) ultrasound examination is useful for several reasons: determination of an accurate date of confinement, diagnostic purposes, and screening for fetal defects. Nuchal translucency measurement combined with maternal serum markers (free b-human chorionic gonadotropin and pregnancy-associated plasma protein A) is the mainstay of first-trimester screening for chromosomal defects. However, over the past decade additional ultrasound markers have been developed that improve the performance of this type of screening. The novel markers include evaluation of the nasal bone, fronto-maxillary angle measurement, and Doppler evaluations of the blood flow across the tricuspid valve and in the ductus venosus.

Reliability of the first-trimester cardiac scan by ultrasound-trained obstetricians with high-frequency transabdominal probes in fetuses with increased nuchal translucency

OBJECTIVE

To examine prospectively the reliability of ultrasound-trained obstetricians performing a first-trimester fetal cardiac scan with high-frequency transabdominal probes, by confirming normal or abnormal heart anatomy, in pregnancies referred for increased nuchal translucency thickness (NT).

METHODS

Trained obstetric operators assessed the fetal heart in 133 fetuses with increased NT (> 95th centile) at 11-14 weeks of gestation. A high-frequency transabdominal probe was used to confirm or refute normal cardiac anatomy rather than to establish a specific diagnosis. Following this preliminary screening by the ultrasound-trained obstetrician, specialized fetal echocardiographers rescanned the fetal heart in order to confirm the accuracy of the obstetric operators' findings and to establish a diagnosis in abnormal cases. Fetal cardiologists repeated the examinations at 20 and 32 weeks of pregnancy. Postnatal follow-up lasted 2 years. Twelve fetuses with normal karyotype and normal anatomy were lost to follow-up.

RESULTS

A total of 121 fetuses with increased NT between 11 and 14 weeks' gestation were studied. Congenital heart disease (CHD) was detected in 20/121 (16.5%) fetuses. In addition, there were three with mild ventricular disproportion, the right ventricle being larger than the left, considered as a minor non-specific cardiac abnormality. CHD was associated with chromosomal anomalies in 12/20 (60%) cases. Among the 121 fetuses, there was agreement between ultrasound-trained obstetricians and fetal cardiologists in 116 (95.9%) of the cases, and the ultrasound-trained obstetricians correctly identified 18 cases with major cardiac defects. However, there was disagreement in five cases: two with small ventricular septal defects and three with ventricular disproportion.

CONCLUSIONS

Our results provide evidence that obstetricians, trained to study the heart in the second trimester, can also differentiate reliably between normal and abnormal heart findings in the first trimester, when using a high-frequency transabdominal ultrasound probe.

Perinatal diagnosis of heart defects

IMPORTANCE OF THE FIELD

Heart defects are the most frequent congenital malformations, affecting 8 in every 1000 neonates. As 90% of infants born with a congenital heart defects (CHD) have no known risk factor, screening for heart defects in every routine obstetric ultrasound is essential for antenatal diagnosis.

AREAS COVERED IN THIS REVIEW

Two-dimensional echocardiography allied with three- and four-dimensional technologies such as spatio-temporal image correlation offer means for thoroughly evaluating fetal cardiac anatomy.

WHAT THE READER WILL GAIN

This article reviews the most relevant aspects of antenatal screening and diagnosis of CHD using sonography and echocardiography. It includes first trimester diagnosis and three- and four-dimensional techniques.

TAKE HOME MESSAGE

These antenatal diagnostic tools play an important role in optimization of obstetric care and neonatal management, thus potentially reducing perinatal mortality.

Nuchal translucency and cystic hygroma colli in screening for fetal major congenital heart defects in a series of 12,910 euploid pregnancies

OBJECTIVE

Many studies have shown that an increased nuchal translucency (NT) may be a good marker of fetal heart malformation, but the extent to which NT is suitable for identifying the population at risk remains unclear. We aimed to determine the value of NT measurement and of the presence of cystic hygroma colli in the screening of euploid fetuses for congenital heart defects (CHD).

METHODS

We carried out a retrospective analysis of 12 910 euploid pregnancies examined between January 1995 and August 2007 at our institution. The screening performance of NT measurements in identifying fetuses with CHD was assessed, with comparison between the use of cut-offs defined as absolute values, multiples of the median (MoM) and percentiles. The presence of cystic hygroma colli was also assessed in the prediction of CHD.

RESULTS

The incidence of major CHD was 3.4 per thousand (44/12 910). The sensitivity of NT measurement in screening for major CHD was 54.5% if the threshold was set at the 95(th) percentile, 45.4% if it was set at 3 mm, 27.3% for 3.5 mm, 50.0% for 1.5 MoM and 45.5% for 1.75 MoM. The false-positive rates for these thresholds were 8.4, 6.6, 1.7, 8.9 and 6.3%, respectively. The incidence of major CHD was 1.2% (10/813) in cases of thick NT (> 95(th) centile) and 4.3% (13/304) in cases of hygroma colli.

CONCLUSIONS

NT measurement during the first trimester is potentially useful for screening for fetal major CHD. Screening performance is consistent whether NT values are expressed as MoMs, percentiles or absolute values. The incidence of major CHD seems to be higher in cases of cystic hygroma colli.

First Trimester Ultrasound Screening: An Update

For many years, the main use of ultrasound in the first trimester of pregnancy was to confirm viability and to establish gestational age. Indeed, the crown-rump length measurement in the first trimester remains the most accurate method to estimate the gestational age even today. However, improvements in ultrasound equipment and improvement in our understanding of normal and abnormal fetal development allows us now to perform a much more complete first trimester fetal evaluation. This pertains not only to the diagnosis of fetal anomalies but also to screening for fetal defects. The combination of the nuchal translucency measurement and maternal serum biochemistries (free β-hCG and PAPP-A) has been shown to be an extremely efficient way to screen for fetal aneuploidy. The addition of other first trimester markers such as the nasal bone evaluation, frontomaxillary facial angle measurement, and Doppler evaluation of blood flow across the tricuspid valve and through the ductus venosus improves the screening performance even further by increasing the detection rates and decreasing the false positive rates. Several of the first trimester markers also are useful in screening for cardiac defects. Furthermore, significant nuchal translucency thickening has been associated with a variety of genetic and nongenetic syndromes. A recently described first trimester marker called the intracerebral translucency appears to hold great promise in screening for open spine defects. Finally, it appears that a first trimester evaluation (uterine artery Doppler and the measurement of certain biochemical markers in the maternal serum) significantly improves the assessment of the risk of preeclampsia.

The nuchal translucency and the fetal heart: a literature review

In this overview the current knowledge of the relationship between an increased nuchal translucency (NT) measurement and fetal heart structure and function in chromosomally normal fetuses is reviewed. Relevant pathophysiological theories behind the increased NT are discussed. Fetuses with an increased NT have an increased risk for congenital heart disease (CHD) with no particular bias for one form of CHD over another. This risk increases with increasing NT measurement. Although the NT measurement is only a modestly effective screening tool for all CHD when used alone, it may indeed be effective in identifying specific CHD "likely to benefit" from prenatal diagnosis. The combination of an increased NT, tricuspid regurgitation and an abnormal ductus venosus (DV) Doppler flow profile, is a strong marker for CHD. A fetal echocardiogram should be performed at 20 weeks' gestation in fetuses with an NT > or = 95th percentile but < 99th percentile. When the NT measurement is > or = 99th percentile, or when tricuspid regurgitation and/or an abnormal DV flow pattern is found along with the increased NT, an earlier echocardiogram is indicated, followed by a repeat scan at around 20 weeks' gestation. The resultant increased demand for early fetal echocardiography and sonographers with this special expertise needs to be planned and provided for.

Prevalence of increased nuchal translucency in fetuses with congenital cardiac disease and a normal karyotype

OBJECTIVES

Our aims were to estimate the prevalence of increased nuchal translucency in fetuses with a normal karyotype that were subsequently diagnosed with congenital cardiac disease on fetal echocardiography, and to assess whether there is a link between increased nuchal translucency and specific congenital cardiac malformations.

METHODS

We reviewed all patients referred to King's College Hospital and the Evelina Children's Hospital in London for fetal echocardiography between January 1998 and December 2007. We investigated the proportion of chromosomally normal fetuses with congenitally malformed hearts in which nuchal thickness was increased, both overall and with specific defects.

RESULTS

We identified 2133 fetuses with congenital cardiac disease by prenatal echocardiography. Of those, 707 were excluded due to abnormal karyotype, and 690 were excluded due to unknown karyotype. The remaining 736 were eligible for inclusion. Among 481 fetuses with documented congenital cardiac disease and normal chromosomes, making up 23% of the overall cohort, 224 had increased nuchal thickness defined as equal or greater than 2.5 millimetres, this being 0.47 of the inclusive cohort, with 95% confidence intervals from 0.42 to 0.51. These proportions were significantly higher than the expected proportion of the normal population, which was 0.05 (p < 0.001). The only diagnosis for which the proportion of fetuses with nuchal translucency measurement equal or greater than 2.5 millimetres was higher than the others was atrioventricular septal defect, with 0.62 of this cohort having abnormal values, with 95% confidence intervals from 0.47 to 0.77 (p = 0.038).

CONCLUSION

We found that nearly half of prenatally diagnosed fetuses with congenitally malformed hearts, when examined ultrasonically in the first or early-second trimester, had increased nuchal thickness. We recommend, therefore, referral of all fetuses with increased nuchal translucency for fetal echocardiography.

Prenatal diagnosis of congenital heart disease

This article presents advancements in the field of fetal echocardiography and the significant impact of these within the fields of pediatric cardiology, perinatology, and neonatology. A prenatal diagnosis of congenital heart disease allows for improved counseling of the parents, guides the timing and optimal location of delivery, and allows appropriate planning and consultation between the cardiologist and neonatologist. It also facilitates accurate diagnosis and management of fetal arrhythmias, identifies potential candidates for in utero cardiac intervention, and serves as the imaging guidance technique for these procedures. The goals, indications, advantages, limitations, and spectrum of congenital heart disease that can be diagnosed are reviewed.

Perinatal echocardiography: protocols for evaluating the fetal and neonatal heart

This Protocol for Evaluating the Fetal and Neonatal Heart details the indications, views, and measurements to be obtained for both (1) the basic screening examination of the fetal heart (a necessary component of all complete fetal anatomy evaluations) and the specialty study called (2) echocardiography as applied to either the fetus or neonate, using 2D and Doppler ultrasound. While the purpose of the screening study is to detect or exclude the possibility of a cardiac abnormality, echocardiography attempts to diagnose the specific anatomic and physiologic disruption. Also emphasized is the value of a collaborative team approach to management of the fetus and its parents when a cardiovascular anomaly is present, in an effort to achieve a smoother transition from fetus to neonate across the continuum of perinatal care.

First trimester ultrasonography in screening and detection of fetal anomalies

An obstetrical ultrasound examination provides invaluable information regarding the fetus. Until the mid-1980s, ultrasound in the first trimester was limited to localization of the pregnancy, establishing viability, and accurate dating. With the advent of high-resolution ultrasound and transvaginal scanning, a significant amount of information about the fetus can be gained and provided to the patient at a very early stage in gestation. This article provides an overview of the role of first trimester (11-13 + 6 weeks' gestation) ultrasound in screening and diagnosis of fetal anomalies. The first trimester is an ideal time for screening for aneuploidy, primarily due to the advantages that nuchal translucency (NT) measurement provides. NT measurement is also useful in establishing the risk of congenital cardiac disorders and a number of genetic and non-genetic syndromes. Significant NT thickening is associated with an increase in perinatal morbidity and mortality. Potential mechanisms resulting in increased NT are discussed. A number of new ultrasound markers for fetal aneuploidy have been investigated over the past several years, some of which appear to improve the screening efficacy of early ultrasonography. The role of these is reviewed. A number of fetal anomalies can now be consistently diagnosed in the first trimester. Their appearance at this early gestational age is discussed as well. It is clear that, data obtained by first trimester ultrasound are useful in counseling expectant parents and in planning the appropriate follow-up.

Nuchal Translucency and the Risk of Congenital Heart Disease

OBJECTIVE

To estimate whether nuchal translucency assessment is a useful screening tool for major congenital heart disease (CHD) in the absence of aneuploidy.

METHODS

Unselected patients with singleton pregnancies at 10(3/7) to 13(6/7) weeks of gestation were recruited at 15 U.S. centers to undergo nuchal translucency sonography. Screening characteristics of nuchal translucency in the detection of major CHD were determined using different cutoffs (2.0 or more multiples of the median [MoM], 2.5 or more MoM, 3.0 or more MoM).

RESULTS

A total of 34,266 euploid fetuses with cardiac outcome data were available for analysis. There were 224 cases of CHD (incidence 6.5 per 1,000), of which 52 (23.2%) were major (incidence 1.5 per 1,000). The incidence of major CHD increased with increasing nuchal translucency: 14.1 per 1,000, 33.5 per 1,000, and 49.5 per 1,000 at 2.0 or more MoM, 2.5 or more MoM, and 3.0 or more MoM cutoffs, respectively. Sensitivity, specificity, and positive predictive values were 15.4%, 98.4%, and 1.4% at 2.0 or more MoM; 13.5%, 99.4%, and 3.3% at 2.5 or more MoM; and 9.6%, 99.7%, and 5.0% at 3.0 or more MoM. Nuchal translucency of 2.5 or more MoM (99th percentile) had a likelihood ratio (95% confidence interval) of 22.5 (11.4-45.5) for major CHD. Based on our data, for every 100 patients referred for fetal echocardiography with a nuchal translucency of 99th percentile or more, three will have a major cardiac anomaly.

CONCLUSION

Nuchal translucency sonography in the first trimester lacks the characteristics of a good screening tool for major CHD in a large unselected population. However, nuchal translucency of 2.5 or more MoM (99th percentile or more) should be considered an indication for fetal echocardiography.

LEVEL OF EVIDENCE

II.

Nuchal translucency measurement and congenital heart defects: modest association in low-risk pregnancies

OBJECTIVE

To assess the performance of nuchal translucency (NT) measurement in the first trimester of pregnancy as a marker for congenital heart defects (CHD) in the fetus in a low-risk obstetric population.

METHODS

Nuchal translucency screening was offered over a 3-year period to consecutive pregnant women without known a priori risk factors and attending midwife practices in three different areas in the Netherlands. In chromosomally normal fetuses and infants from the study population the NT measurements were matched with CHD detected either prenatally or postnatally.

RESULTS

NT screening was offered to 6132 women with an uptake of 83%. A total of 4876 NT measurements was performed. Pregnancy outcome data were available in 4181 cases (86%). Defects of the heart and great arteries (CHD) were diagnosed in 24 cases (prevalence 5.8/1000). Thirteen of these were classified as major (prevalence 3.1/1000). Two major CHD occurred in fetuses showing an increased NT at the first-trimester scan. The sensitivity of NT measurement > 95th and > 99th percentile for all CHD and for major CHD, was 8% and 15%, respectively. The positive likelihood ratios of NT > 95(th) and > 99th percentile for major CHD were 6, 5 and 33, respectively.

CONCLUSION

In pregnancies without known risk factors also, an increased NT is associated with major cardiac defects in the fetus and therefore represents an indication for specialized fetal echocardiography. However, this association is too weak to envisage a role for NT measurement as single screening strategy for the prenatal detection of cardiac defects.

First Trimester Down’s Syndrome Screening Shows High Detection Rate for Trisomy 21, but Poor Performance in Structural Abnormalities – Regional Outcome Results

OBJECTIVE

To evaluate whether first trimester screening markers are altered in pregnancies affected both by other chromosomal defects than trisomy 21 and structural anomalies and whether it is possible to detect these pregnancies by combined ultrasound and biochemical screening test.

METHODS

Altogether 4,776 singleton pregnancies underwent first trimester screening. Of them, 3,101 women were screened using a combination of maternal serum free hCG, pregnancy-associated plasma protein A and nuchal translucency and 1,361 women with first trimester biochemistry without ultrasound. Nuchal translucency screening was performed between the 11th and 13+6th gestational weeks, and biochemistry 1-2 weeks earlier.

RESULTS

Using a fixed cut-off rate of 1:250 for Down's syndrome, the detection rate of trisomies 21, 18 and 13 were 92, 67 and 0%, respectively. All open defects, 85% of cardiac defects and other minor defects were not detected in first trimester screening. Majority of these structural abnormalities occurred in women under 35 years of age.

CONCLUSION

First trimester Down's syndrome screening is effective in trisomy screening, but its performance in structural abnormalities is low, when used as a part of routine clinical practice. We conclude that it is too early to drop second trimester screening ultrasound entirely from antenatal care programs if a high detection rate is to be achieved also in structural defects.

Is measurement of nuchal translucency thickness a useful screening tool for heart defects? A study of 16,383 fetuses

OBJECTIVE

To determine the performance of nuchal translucency thickness (NT) measurement as a screening method for congenital heart defects (CHD) among fetuses with normal karyotype.

METHODS

An NT measurement was made in 16 383 consecutive euploid fetuses derived from an unselected pregnant population. The cut-offs for increased risk of heart defects, chosen a priori and tested prospectively, were: NT >or= 95th centile for crown-rump length, NT >or= 3 mm, and NT >or= 3.5 mm. The sensitivity and false-positive rate (FPR; 1 minus specificity) of the risk cut-offs and their positive and negative likelihood ratios (+LR and -LR) with regard to CHD were calculated.

RESULTS

Among the 16 383 fetuses with an NT measurement there were 127 cases with a diagnosis of heart defect confirmed by cardiac investigations after birth or at autopsy. Of these, 55 defects were defined as major, of which 52 were isolated (no other defects or chromosomal aberrations), corresponding to a prevalence of major heart defects in chromosomally normal fetuses/newborns of 3.3/1000. The sensitivity, FPR, +LR and -LR for NT >or= 95th centile with regard to an isolated major heart defect were: 13.5%, 2.6%, 5.2 and 0.9, respectively. For NT >or= 3.0 mm these values were: 9.6%, 0.8%, 12.0 and 0.9, and for NT >or= 3.5 mm they were: 5.8%, 0.3%, 19.3 and 0.9.

CONCLUSIONS

NT measurement is a poor screening method for isolated major CHD. A method with a much higher detection rate and with a reasonably low FPR is needed. However, increased NT indicates increased risk of fetal heart defect, and women carrying fetuses with increased NT should be offered fetal echocardiography in the second trimester.

Fetal echocardiography: where are we?

This article reviews the indications, technique and benefits of fetal echocardiography. The impact of fetal echocardiography has become evident with better surgical outcome of infants with prenatal diagnosis of congenital heart disease. A major use of this technique has also been shown in the field of fetal arrhythmias. Fetal echocardiography is not only used to diagnose a specific type of arrhythmia, it is also very helpful in assessing the effect of the arrhythmia on the fetus and in guiding transplacental therapy. However it is important to remember that even experienced echocardiographers can make both false positive and false negative diagnosis of congenital heart disease. As fetal cardiac interventions including fetal cardiac surgery loom on the horizon, fetal echocardiography assumes further importance.

Prenatal diagnostic decision-making in adolescents

STUDY OBJECTIVE

We sought to evaluate the prenatal decision-making of pregnant adolescents identified at increased risk for identifiable fetal genetic abnormalities.

DESIGN

A retrospective review of records of gravid women 19 years old or younger undergoing genetic counseling from 2001-2003 (inclusive) was undertaken.

SETTING

Hospital-based academic center.

PARTICIPANTS

Thirty-seven women were identified; four cases did not meet inclusion criteria.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE

Decision to undergo or forgo invasive prenatal testing.

RESULTS

Of the 33 women included in this study, the average age was 17.6 years (range: 15-19). Eighteen were Latinas, eight were African-Americans, and seven were Caucasians. Sixteen women had positive maternal serum screening outcomes; nine women sought counseling because of personal/family histories of genetic abnormalities, seven sought counseling after fetal structural anomalies were detected by ultrasound, and one woman sought counseling because she and her partner were positive for Mendelian disorder screening (sickle cell disease). Sixteen of the women (48.5%) chose to undergo invasive testing (15 amniocenteses, one chorionic villus sampling) whereas 17 (51.5%) chose to forgo invasive testing.

CONCLUSIONS

Adolescents offered invasive prenatal diagnosis will chose to undergo or forgo such testing based on diagnostic and personal criteria as do adult women. Nonetheless, unique adolescent issues may make the process by which information is obtained and communicated during counseling to be different from counseling provided to adults. The development of new genetic screening and diagnostic protocols has and will increase the number of pregnant adolescent women who will be offered genetic counseling during their pregnancies. Such an increase in numbers will place considerably more pressure on an already taxed genetic counseling system; accordingly, new counseling paradigms will need to be developed to provide service to an expanded patient population seeking information for an increasing number of genetic issues.

Increased nuchal translucency with normal karyotype

Increased fetal nuchal translucency (NT) thickness between 11 and 14 weeks' gestation is a common phenotypic expression of chromosomal abnormalities, including trisomy 21. However, even in the absence of aneuploidy, nuchal thickening is clinically relevant because it is associated with an increase in adverse perinatal outcome caused by a variety of fetal malformations, dysplasias, deformations, dysruptions, and genetic syndromes. Once the presence of aneuploidy is ruled out, the risk of perinatal outcome dose not statistically increase until the nuchal translucency measurement reaches 3.5 mm or more (>99th percentile). This increase in risk occurs in an exponential fashion as the NT measurement increases. However, if the fetus survives until midgestation, and if a targeted ultrasound at 20 to 22 weeks fails to reveal any abnormalities, the risk of an adverse perinatal outcome and postnatal developmental delay is not statistically increased.

Frontiers in fetal cardiovascular disease

This article reviews the state of the art in prenatal cardiovascular imaging, the elucidation of regional vascular flow patterns in the developing fetus and what can be learned from these flow patterns, the new clinical practice systems being that are being implemented to deal with the fetal patient and its family, and the prospects for fetal surgery.

The clinical evaluation and pregnancy outcome of euploid fetuses with increased nuchal translucency

This review aims to address the systematic work-up and counseling throughout pregnancies with increased nuchal translucency (NT) in euploid fetuses. Original articles from peer-reviewed English-language journals between 1997 and 2003 were studied. They all included descriptions of pregnancy outcomes of euploid fetuses with increased NT. Eleven studies reporting on the pregnancy outcome of 2128 euploid fetuses with increased NT (> or = 3 mm or > or = 95 centile) were retrieved by our literature search. A statistical analysis was conducted for assessing the consistency of effects across studies. The chi2 tests were applied to verify the homogeneity of the results from different series. A significant difference was found between the studies even when the results were analyzed separately according to various NT cutoff levels (i.e. > or = 3 mm, > or = 3.5-4 mm, and > or = 95 centile). These discrepancies suggest that those studies are significantly different and therefore, cannot be combined for meta-analysis. Of all the reported series, 2.2-10.6% of the fetuses have miscarried and 0.5-15.8% ended in perinatal death. There was an overall rate of 0.5-12.7% neurodevelopmental problems, and 2.1-7.6% of the malformations which were undiagnosed before birth. Importantly, 70-90% fetuses had normal outcomes. A detailed two-step anomaly scan including midgestation fetal echocardiography should be part of perinatal management of pregnancies with increased fetal NT. Data on relevant family history and persistence of nuchal edema provide additional relevant information for planning pregnancy management.

Fetal cardiac defects and increased nuchal translucency thickness: a prospective study

OBJECTIVE

The purpose of this study was to examine prospectively the association between increased nuchal translucency thickness and major cardiac defects in chromosomally normal fetuses.

STUDY DESIGN

A prospective cohort study of 263 chromosomally normal fetuses with an increased nuchal translucency thickness at 11 to 14 weeks of gestation at a tertiary referral center was performed. The incidence of major cardiac defects was examined in relation to the fetal nuchal translucency thickness at the 11 to 14 week ultrasound examination.

RESULTS

The nuchal translucency thickness measurements ranged from 2.2 to 8.0 mm (median, 3.1 mm). There were 13 cases of major cardiac defects in this cohort, which gave a prevalence of 49.4 of every 1000 fetuses. With the use of the 99th percentile of nuchal translucency thickness, the prevalence rose to 106.7 of every 1000 fetuses.

CONCLUSION

In this population of chromosomally normal fetuses with an increased nuchal translucency thickness, the incidence of cardiac defects was high, which suggests that fetal echocardiography is indicated in this group.

Does nuchal translucency have a role in fetal cardiac screening?

Increased nuchal translucency is the strongest single marker for chromosomal abnormality. Consequently, it is currently becoming established as the foundation of most early screening programmes for Down syndrome. In the absence of chromosomal abnormality, increased nuchal translucency has been shown to be associated with other congenital anomalies including cardiac defects. Several datasets have now reported this association and here these are reviewed to assess the effectiveness of nuchal translucency measurement as a screening tool for the prenatal detection of congenital heart disease.