Increased nuchal translucency in euploid fetuses--what should we be telling the parents?

Antenatal screening for fetal structural anomalies - Routine or targeted practice?

Antenatal screening with ultrasound identifies fetal structural anomalies in 3-6% of pregnancies. Identification of anomalies during pregnancy provides an opportunity for counselling, targeted imaging, genetic testing, fetal intervention and delivery planning. Ultrasound is the primary modality for imaging the fetus in pregnancy, but magnetic resonance imaging (MRI) is evolving as an adjunctive tool providing additional structural and functional information. Screening should start from the first trimester when more than 50% of severe defects can be detected. The mid-trimester ultrasound balances the benefits of increased fetal growth and development to improve detection rates, whilst still providing timely management options. A routine third trimester ultrasound may detect acquired anomalies or those missed earlier in pregnancy but may not be available in all settings. Targeted imaging by fetal medicine experts improves detection in high-risk pregnancies or when an anomaly has been detected, allowing accurate phenotyping, access to advanced genetic testing and expert counselling.

Adverse pregnancy outcome in fetuses with early increased nuchal translucency: prospective cohort study

OBJECTIVES

An increased nuchal translucency (NT) thickness of ≥ 3.5 mm is a well-established marker for congenital anomalies and adverse pregnancy outcome between 11 and 14 weeks' gestation, but little is known about its performance as a screening tool before 11 weeks. We aimed to investigate, in a prospective setting, whether fetuses with increased NT before 11 weeks are at risk for adverse pregnancy outcome.

METHODS

This was a prospective cohort study including pregnant women with a viable fetus with NT ≥ 2.5 mm and a crown-rump length (CRL) < 45 mm. All included women were referred to our fetal medicine unit (FMU) and scheduled for a follow-up scan where the NT was remeasured after 1 week when the CRL was > 45 mm. Two groups were evaluated: cases with a normalized NT (< 3.5 mm) and cases with persistently increased NT (≥ 3.5 mm). The cases were monitored until 4 weeks after delivery. The main outcome was a composite adverse outcome of aneuploidy, other genetic disorders, structural anomalies and pregnancy loss. We performed subgroup analyses of NT thickness at inclusion and normalized or persistently increased NT at follow-up.

RESULTS

The study included 109 cases, of which 39 (35.8%) had an adverse pregnancy outcome. Of these, 64.1% (25/39) were aneuploid, corresponding to 22.9% (25/109) of the total study population. In the subgroups of NT thickness at inclusion of 2.5-3.4 mm, 3.5-4.4 mm and ≥ 4.5 mm, an adverse outcome was reported in 22.0% (9/41), 40.0% (18/45) and 52.2% (12/23), respectively. In fetuses with a normalized NT and without ultrasound abnormalities at the follow-up scan, the incidence of adverse outcome was 8.5% (5/59), of which 5.1% (3/59) cases were aneuploid.

CONCLUSIONS

Fetuses with an early increased NT thickness are at considerable risk of an adverse pregnancy outcome, even if the NT normalizes after 11 weeks. Not all congenital anomalies can be diagnosed with routine first-trimester screening, such as non-invasive prenatal testing and/or a first-trimester anomaly scan. Therefore, expectant parents should always be referred to a FMU for detailed ultrasonography. Invasive prenatal testing should be offered if an increased NT of ≥ 2.5 mm is observed before 11 weeks' gestation. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal whole-exome sequencing in fetuses with increased nuchal translucency

BACKGROUND

Increased nuchal translucency (NT) is associated with an increased risk for genetic disorders. The aim of this study was to investigate the value of whole-exome sequencing (WES) in detecting genetic abnormalities for fetuses with isolated first-trimester increased NT.

METHODS

After the exclusion of aneuploidies and pathogenic copy number variants (CNVs) by quantitative fluorescent polymerase chain reaction (QF-PCR) and chromosomal microarray analysis (CMA), WES was performed on 63 fetuses with isolated first-trimester increased NT (≥3.5 mm).

RESULTS

Overall, WES yielded a 4.8% (3/63) diagnostic rate for fetuses with isolated increased NT. Pathogenic variants were identified in 37.5% (3/8) fetuses that developed additional structural anomalies later in gestation, and no pathogenic variants were detected in increased NT that resolved or remained isolated throughout the pregnancy.

CONCLUSION

This study provides powerful evidence to offer prenatal WES for increased NT only when additional abnormalities are present. Early detailed ultrasound to detect emerging anomalies can help physicians offer prenatal WES to fetuses with a greater likelihood of diagnosis.

When NIPT meets WES, prenatal diagnosticians face the dilemma: genetic etiological analysis of 2,328 cases of NT thickening and follow-up of pregnancy outcomes

Objective: To assess the performance of diverse prenatal diagnostic approaches for nuchal translucency (NT) thickening and to investigate the optimal prenatal screening or diagnostic action with a NT thickening of 95th percentile-3.50 mm. Methods: A retrospective analysis of 2,328 pregnancies with NT ≥ 95th percentile through ultrasound-guided transabdominal chorionic villus sampling (CVS), amniocentesis, or cordocentesis obtained clinical samples (chorionic villi, amniotic fluid, and cord blood), and real-time quantitative fluorescent PCR (QF-PCR), chromosome karyotyping (CS), chromosome microarray analysis (CMA), or whole exome sequencing (WES) were provided to identify genetic etiologies. Results: In this study, the incidence of chromosomal defects increased with NT thickness. When NT ≥ 6.5 mm, 71.43% were attributed to genetic abnormalities. The 994 gravidas with fetal NT thickening underwent short tandem repeat (STR), CS, and CMA. In 804 fetuses with normal karyotypes, CMA detected 16 (1.99%) extra pathogenic or likely pathogenic copy number variations (CNVs). The incremental yield of CMA was only 1.16% (3/229) and 3.37% (10/297) in the group with NT 95th percentile-2.99 mm and NT 3.0-3.49 mm, separately. Among the 525 gravidas with fetal NT thickening who underwent STR, CMA, and WES, the incremental yield of WES was 4.09% (21/513). In the group of NT 95th percentile-2.99 mm, there were no additional single-nucleotide variations (SNVs) detected in WES, while in 143 cases with NT of 3.0-3.49 mm, the incremental yield of WES was 5.59% (8/143). Conclusion: In the group of NT 95th percentile-3.0 mm, since chromosomal aneuploidy and chromosomal copy number variation were the primary causes and the additional contribution of CMA and WES was not significant, we recommend NIPT-Plus for pregnant women with a NT thickening of 95th percentile-3.0 mm first. In addition, comprehensive prenatal genetic testing involving CMA and WES can benefit pregnancies with NT thickening of 3.0-3.49 mm.

Case report: A case of incontinentia pigmenti

Incontinentia pigmenti (IP) is a rare neuroectodermal dysplasia caused by mutations in the IKBKG gene. We present a case of a 4-month-old female infant with erythematous vesicular skin lesions on the trunk and extremities. Histopathologic examination of the blisters revealed an eosinophilic infiltrate. Further investigation revealed that her mother had three unexplained miscarriages and two normal uncomplicated pregnancies, resulting in the birth of two male infants. We performed a comprehensive genetic evaluation to rule out the interference of pseudogene IKBKGP, and the infant was finally diagnosed with IP. During the subsequent 2-year follow-up, we observed a significant improvement in her dermatologic symptoms, with no evidence of recurrence, and there were no other associated symptoms in the hair, nails, oral mucosa, eyes, or central nervous system.

Increased nuchal translucency in children with congenital heart defects and normal karyotype-is there a correlation with mortality?

OBJECTIVES

Our objective was to investigate if an increased nuchal translucency (NT) was associated with higher mortality in chromosomally normal children with congenital heart defects (CHD).

METHODS

In a nationwide cohort using population-based registers, we identified 5,633 liveborn children in Denmark with a pre- or postnatal diagnosis of CHD from 2008 to 2018 (incidence of CHD 0.7%). Children with chromosomal abnormalities and non-singletons were excluded. The final cohort compromised 4,469 children. An increased NT was defined as NT > 95th-centile. Children with a NT > 95th-centile vs. NT < 95th-centile including subgroups of simple- and complex CHD were compared. Mortality was defined as death from natural causes, and mortalities were compared among groups. Survival analysis with Cox-regression was used to compare rates of mortality. Analyses were adjusted for mediators (possibly explanatory factors between increased NT and higher mortality): preeclampsia, preterm birth and small for gestational age. And for confounding effects of extracardiac anomalies and cardiac intervention, due to their close association to both the exposure and the outcome (i.e., confounders).

RESULTS

Of the 4,469 children with CHD, 754 (17%) had complex CHD and 3,715 (83%) simple CHD. In the combined group of CHDs the mortality rate was not increased when comparing those with a NT > 95th-centile to those with a NT < 95th-centile [Hazard ratio (HR) 1.6, 95%CI 0.8;3.4, p = 0.2]. In simple CHD there was a significantly higher mortality rate with a HR of 3.2 (95%CI: 1.1;9.2, p = 0.03) when having a NT > 95th centile. Complex CHD had no differences in mortality rate between a NT > 95th-centile and NT < 95th-centile (HR 1.1, 95%CI: 0.4;3.2, p = 0.8). All analysis adjusted for severity of CHD, cardiac operation and extracardiac anomalies. Due to limited numbers the association to mortality for a NT > 99th centile (>3.5 mm) could not be assessed. Adjustment for mediating (preeclampsia, preterm birth, small for gestational age) and confounding variables (extracardiac anomalies, cardiac intervention) did not alter the associations significantly, except for extracardiac anomalies in simple CHD.

CONCLUSION

An increased NT > 95th-centile is correlated with higher mortality in children with simple CHD, but the underlying cause is unknown and undetected abnormal genetics might explain the correlation rather than the increased NT itself, hence further research is warranted.

Prenatal Diagnosis of Euploid Increased Nuchal Translucency on Fetal Ultrasound (II): RASopathy Disorders - Prenatal Ultrasound Findings and Genotype-phenotype Correlations

Prenatal diagnosis of euploid increased nuchal translucency (NT) remains a challenge to obstetricians and genetic counselors, although increased euploid NT at prenatal diagnosis can be associated with a favorable outcome. Prenatal diagnosis of euploid increased NT should include a differential diagnosis of pathogenetic copy number variants and RASopathy disorders (RDs) including Noonan syndrome. Therefore, chromosomal microarray analysis, whole-exome sequencing, RASopathy-disorder testing, and protein-tyrosine phosphatase nonreceptor type 11 gene testing may be necessary under such a circumstance. In this report, a comprehensive review of RDs with its prenatal ultrasound findings and genotype-phenotype correlations is presented.

Increased nuchal translucency with normal karyotype and genomic microarray analysis: A multicenter observational study

OBJECTIVE

To define the residual risk of morbidity-related outcome in fetuses with nuchal translucency (NT) of 3.5 mm or more after normal genetic testing and mid-trimester anomaly scan.

METHODS

A total of 114 fetuses with isolated NT of 3.5 mm or more, normal karyotype, and array-based comparative genomic hybridization (array-CGH) were included and divided in three groups: NT 3.5-4.5 mm, NT 4.5-6 mm, and NT greater than 6 mm. RASopathy testing and ultrasound follow up were performed in all fetuses. We evaluated: (1) incidence of genetic disorders; (2) incidence of structural abnormalities; (3) pregnancy outcome; (4) long-term pediatric outcome before (point 1) and after (point 2) a normal RASopathy testing and mid-trimester anomaly scan.

RESULTS

After normal karyotype and array-CGH the residual risk of morbidity-related outcome was 24.64% for NT 3.5-4.5 mm, 25% for NT 4.5-6 mm and 76.47% for NT more than 6 mm. After a normal RASopathy testing and mid-trimester anomaly scan the residual risks decreased to 7.14%, 8.69%, and 33.3% in the three groups, respectively.

CONCLUSION

In fetuses with an NT of 3.5 mm or more and both normal karyotype and array-CGH, the rate of morbidity-related outcome depends on NT size. A normal RASopathy testing and mid-trimester ultrasound are reassuring but the residual risk of morbidity-related outcome is increased compared with the general population, particularly if NT is greater than 6 mm.

Next Generation Sequencing after Invasive Prenatal Testing in Fetuses with Congenital Malformations: Prenatal or Neonatal Investigation

Congenital malformations diagnosed by ultrasound screening complicate 3–5% of pregnancies and many of these have an underlying genetic cause. Approximately 40% of prenatally diagnosed fetal malformations are associated with aneuploidy or copy number variants, detected by conventional karyotyping, QF-PCR and microarray techniques, however monogenic disorders are not diagnosed by these tests. Next generation sequencing as a secondary prenatal genetic test offers additional diagnostic yield for congenital abnormalities deemed to be potentially associated with an underlying genetic aetiology, as demonstrated by two large cohorts: the ‘Prenatal assessment of genomes and exomes’ (PAGE) study and ‘Whole-exome sequencing in the evaluation of fetal structural anomalies: a prospective cohort study’ performed at Columbia University in the US. These were large and prospective studies but relatively ‘unselected’ congenital malformations, with little Clinical Genetics input to the pre-test selection process. This review focuses on the incremental yield of next generation sequencing in single system congenital malformations, using evidence from the PAGE, Columbia and subsequent cohorts, with particularly high yields in those fetuses with cardiac and neurological anomalies, large nuchal translucency and non-immune fetal hydrops (of unknown aetiology). The total additional yield gained by exome sequencing in congenital heart disease was 12.7%, for neurological malformations 13.8%, 13.1% in increased nuchal translucency and 29% in non-immune fetal hydrops. This demonstrates significant incremental yield with exome sequencing in single-system anomalies and supports next generation sequencing as a secondary genetic test in routine clinical care of fetuses with congenital abnormalities.

Isolated Increased Nuchal Translucency in First Trimester Ultrasound Scan: Diagnostic Yield of Prenatal Microarray and Outcome of Pregnancy

Background: Increased nuchal translucency (NT) is associated with aneuploidy. When the karyotype is normal, fetuses are still at risk for structural anomalies and genetic syndromes. Our study researched the diagnostic yield of prenatal microarray in a cohort of fetuses with isolated increased NT (defined as NT ≥ 3.5 mm) and questioned whether prenatal microarray is a useful tool in determining the adverse outcomes of the pregnancy. Materials and Methods: A prospective study was performed, in which 166 women, pregnant with a fetus with isolated increased NT (ranging from 3.5 to 14.3 mm with a mean of 5.4 mm) were offered karyotyping and subsequent prenatal microarray when karyotype was normal. Additionally, all ongoing pregnancies of fetuses with normal karyotype were followed up with regard to postnatal outcome. The follow-up time after birth was maximally 4 years. Results: Totally, 149 of 166 women opted for prenatal testing. Seventy-seven fetuses showed normal karyotype (52%). Totally, 73 of 77 fetuses with normal karyotype did not show additional anomalies on an early first trimester ultrasound. Totally, 40 of 73 fetuses received prenatal microarray of whom 3 fetuses had an abnormal microarray result: two pathogenic findings (2/40) and one incidental carrier finding. In 73 fetuses with an isolated increased NT, 21 pregnancies showed abnormal postnatal outcome (21/73, 28.8%), 29 had a normal outcome (29/73, 40%), and 23 were lost to follow-up (23/73, 31.5%). Seven out of 73 live-born children showed an adverse outcome (9.6%). Conclusions: Prenatal microarray in fetuses with isolated increased NT had a 5% (2/40) increased diagnostic yield compared to conventional karyotyping. Even with a normal microarray, fetuses with an isolated increased NT had a 28.8% risk of either pregnancy loss or an affected child.

Increased nuchal translucency before 11 weeks of gestation: Reason for referral?

OBJECTIVES

In this era of non-invasive-prenatal testing (NIPT), when dating scans are usually performed around 10 weeks of gestation, an increased NT before the official established timeframe (CRL between 45 and 84 mm) may be encountered. Information on management of these pregnancies is limited. Therefore, we evaluated the relationship between an early increased NT and adverse pregnancy outcome. Secondary, we evaluated the rate of chromosomal anomalies that might have been missed in first trimester should solely NIPT be performed as first-tier test, and the rate of adverse pregnancy outcome if NT normalizes before 14 weeks.

METHODS

We performed a retrospective cohort study that included all pregnancies between January 1, 2007 and June 1, 2020 in Amsterdam UMC locations AMC and VUmc. We included fetuses with a crown-rump length (CRL) < 45 mm (∼11 weeks) and a nuchal translucency (NT) measurement ≥2.5 mm. Fetuses referred with an early increased NT and a major fetal anomaly at the dating scan were excluded, as were cases of parents with a family history of monogenetic disease(s) or recognized carriers of a balanced translocation.

RESULTS

We included 120 fetuses of which 66.7% (80/120) had an adverse pregnancy outcome. Congenital anomalies were present in 56.7% (68/120), 45.8% (55/120) had a chromosomal anomaly. The prevalence of congenital anomalies was 30.3% in fetuses with NT 2.5-3.4 mm compared to 66.7% with NT ≥ 3.5 mm (p < 0.001). 16.7% (20/120) had a chromosomal anomaly that might have been missed by conventional NIPT in first trimester. We found an adverse pregnancy outcome of 24% in the group with a normalized NT compared to 78.1% in the group with a persistently increased NT (p < 0.001).

CONCLUSION

An early increased NT should make the sonographer alert. In this selected cohort, an early increased NT was associated with a high probability of having an adverse pregnancy outcome. Regardless of CRL, we deem that an early increased NT ≥ 3.5 mm warrants referral to a Fetal Medicine Unit for an extensive work-up. NT normalization seems favorable, but a prospective study should define the appropriate work-up for NT in the lower range (2.5-3.4 mm).

Fetal exome sequencing for isolated increased nuchal translucency: should we be doing it?

Objective

To evaluate the utility of prenatal exome sequencing (ES) for isolated increased nuchal translucency (NT) and to investigate factors that increase diagnostic yield.

Design

Retrospective analysis of data from two prospective cohort studies.

Setting

Fetal medicine centres in the UK and USA.

Population

Fetuses with increased NT ≥3.5 mm at 11–14 weeks of gestation recruited to the Prenatal Assessment of Genomes and Exomes (PAGE) and Columbia fetal whole exome sequencing studies (n = 213).

Methods

We grouped cases based on (1) the presence of additional structural abnormalities at presentation in the first trimester or later in pregnancy, and (2) NT measurement at presentation. We compared diagnostic rates between groups using Fisher exact test.

Main outcome measures

Detection of diagnostic genetic variants considered to have caused the observed fetal structural anomaly.

Results

Diagnostic variants were detected in 12 (22.2%) of 54 fetuses presenting with non‐isolated increased NT, 12 (32.4%) of 37 fetuses with isolated increased NT in the first trimester and additional abnormalities later in pregnancy, and 2 (1.8%) of 111 fetuses with isolated increased NT in the first trimester and no other abnormalities on subsequent scans. Diagnostic rate also increased with increasing size of NT.

Conclusions

The diagnostic yield of prenatal ES is low for fetuses with isolated increased NT but significantly higher where there are additional structural anomalies. Prenatal ES may not be appropriate for truly isolated increased NT but timely, careful ultrasound scanning to identify other anomalies emerging later can direct testing to focus where there is a higher likelihood of diagnosis.

Prenatal ES has a low diagnostic rate (<2%) for isolated increased NT but is significantly more likely to yield a diagnosis where there are additional fetal structural anomalies.

Linked article This article is commented on by AN Talati and NL Vora, p. 61–62 in this issue. To view this mini commentary visit https://doi.org/10.1111/1471-0528.16942.

Increased nuchal translucency after low-risk noninvasive prenatal testing: What should we tell prospective parents?

Three decades ago, the observation that first trimester fetuses with excess fluid accumulation at the back of the neck were more likely to be aneuploid, gave rise to a new era of prenatal screening. The nuchal translucency (NT) measurement in combination with serum biomarkers and maternal age, resulted in the first trimester combined screening (FTCS) program. The introduction of noninvasive prenatal testing (NIPT) over the past decade has introduced the option for parents to receive highly sensitive and specific screening information for common trisomy from as early as 10 weeks gestation, altering the traditional pathway FTCS pathway. The retention of the 11-13-week NT ultrasound remains important in the detection of structural anomalies; however, the optimal management of pregnancies with a low-risk NIPT result and an isolated increased NT measurement in an era of advanced genomic testing options is a new dilemma for clinicians. For parents, the prolonged period between the initial diagnosis in first trimester, and prognostic information at each successive stage of investigations up to 22-24 weeks, can be emotionally challenging. This article addresses the common questions from parents and clinicians as they navigate the uncertainty of having a fetus diagnosed with an increased NT after a low-risk NIPT result and presents suggested approaches to management.

Cardiac axis evaluation as a screening method for detecting cardiac abnormalities in the first trimester of pregnancy

Congenital cardiac abnormalities refer to especially anatomic malformations of the heart that normally occur during fetal heart development, before eight weeks after conception. Aim: The aim is to investigate the association between cardiac axis and congenital heart abnormalities for a potential underline clinical application of cardiac axis evaluation during detection by abnormalities at the time of first trimester ultrasound. It is known that aneuploids can be associated in almost half of cases with cardiac abnormalities, so the angle of the cardiac axis could be a potential indirect marker for the detection of aneuploids in the first trimester of pregnancy. Being easy to obtain, from the cross-section at the chest level with the visualization of the four chambers, does not require additional sections to those provided in the current guides, we aim to prove its usefulness in diagnosing aneuploids and congenital cardiac abnormalities along with the translucent nuchal flow, at the level of the venous duct and the presence of tricuspid regurgitation. Conclusions: Cardiac axis has a higher value for the detection of congenital cardiac abnormalities with respect to the nuchal translucency, tricuspid regurgitation and inverted A wave at the level of the venous duct.

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

We evaluated the association of nuchal translucency (NT) values above 99th percentile with perinatal outcomes. Materials and methods: Singleton pregnancies with NT values above 99th percentile were investigated. Pregnancies were divided into 3 groups: group 1, NT = 2.6-<3.5 mm; group 2, NT = 3.5-4.5 mm; and group 3, NT > 4.5 mm. Demographic features, clinical characteristics, structural/chromosomal anomaly rates and perinatal outcomes were compared. Results: Normal ultrasonographic anatomy was found in 47.5%, 7.7%, and 14.3% of groups 1, 2, and 3, respectively (p = 0.006). Group 3 had the lowest normal karyotype rate (44.6%) (p = 0.005). Higher frequencies for both miscarriage and pregnancy termination were observed in group 3 compared to group 1 (8.9% vs. 4.9% and 66.1% vs. 32.7%, respectively) (p = 0.02). The lowest rate of normal postnatal anatomic findings was found in group 3 (10.7%) (p = 0.01). Conclusion: NT values above 99th percentile for gestational age seem to be associated with increased rates of chromosomal/structural abnormalities and adverse perinatal outcomes.

First-trimester absent nasal bone: is it a predictive factor for pathogenic CNVs in the low-risk population?

OBJECTIVE

To evaluate the association of first-trimester absent nasal bone (NB) and genetic abnormalities at G-banding karyotype and chromosomal microarray analysis (CMA) according to the nuchal translucency (NT) thickness.

METHODS

This is a retrospective cohort study of fetuses that underwent the first-trimester scan for the combined test at 11⁺⁰ to 13⁺⁶ weeks' gestation. Invasive test with G-banding karyotype and/or CMA was performed based on the result of the combined test or if fetal defects were detected or for patient's choice, after genetic counseling. All cases with absent NB in the first and second trimester underwent a detailed anomaly scan with echocardiography in the second trimester, had a longitudinal ultrasound, and postnatal follow-up up to at least 1 year.

RESULTS

Between 2013 and 2018, 7228 women underwent the first-trimester scan at 11⁺⁰ to 13⁺⁶ weeks. Overall prevalence of absent NB was 1.3% (96/7228). Of those, in 86 pregnancies (1.2%), the absence of NB was confirmed also in the second trimester: 0.58% (40/6909) in the group with NT <95th centile; 6%(14/233) in the group with NT between 95 and 99th centile; and 37.2% (32/86) in the group with NT >99th centile, respectively. CMA pathogenic variants were found only in the group with NT >99th centile with a diagnostic yield of 9.4%. Fetuses with absent NB and NT between 95 and 99th centile had in 57% (8/14) a major chromosomal anomaly, while in the NT <95 centile group, there were 5% (2/40) of chromosomal abnormalities (one inherited from the father).

CONCLUSION

In the first trimester, the risk for genetic syndromes detectable by CMA is related mainly to the NT thickness rather than to the absence of NB per se. In fetuses with absent NB and NT >99th centile, CMA should be performed after karyotype analysis, while for NT between 95 and 99th centile, a karyotype should be proposed as first-line procedure. Data provided by our study may be helpful in counseling women/couples when an absent NB is identified in the first trimester.

Microarray and RASopathy-disorder testing in fetuses with increased nuchal translucency

OBJECTIVES

To determine the incidence of chromosomal abnormalities, submicroscopic chromosomal abnormalities and RASopathy-disorder (RD) pathogenic variants in a cohort of pregnancies with nuchal translucency thickness (NT) ≥ 3.5 mm, and to propose a clinical protocol for surveillance of this group of patients.

METHODS

This was a retrospective chart review of patients referred to The Prenatal Diagnosis and Medical Genetics Program at Mount Sinai Hospital between January 2013 and December 2015, due to NT ≥ 3.5 mm, who underwent chorionic villus sampling or amniocentesis. Patients underwent extensive genetic counseling prior to invasive procedures and testing. Quantitative fluorescence polymerase chain reaction (QF-PCR) was performed as the first-line test for aneuploidy. If the result was negative, patients underwent karyotyping and/or chromosomal microarray analysis (CMA), and if the findings were normal, they had testing for RD pathogenic variants, which included nine known genes. Patients also underwent detailed fetal ultrasound examinations and echocardiography, performed by expert operators.

RESULTS

A total of 226 eligible patients were identified. In 116/226 (51.3%) patients, QF-PCR identified a chromosomal aneuploidy. The remaining 110/226 (48.7%) patients had further genetic testing. Karyotyping/CMA detected an abnormal/pathogenic cytogenetic result in 9/110 (8.2%) patients, as well as five variants of unknown significance (VOUS). RD testing yielded three pathogenic variants (3/103), giving a detection rate of 2.9%, and one VOUS. The optimal NT cut-off for RD screening was 7.9 mm in this population. In 92/110 (83.6%) patients, the genetic investigations were normal. Of these pregnancies, an early (14-16 weeks' gestation) detailed fetal ultrasound examination identified a structural abnormality in 24 (26.1%), 15 (16.3%) had an abnormal detailed ultrasound examination at 18-22 weeks' gestation and fetal echocardiography showed a cardiac abnormality in nine (9.8%). The birth outcome in the 83 pregnancies that had normal genetic investigations and known outcome included seven (8.4%) cases of termination of pregnancy, seven (8.4%) cases of intrauterine fetal death and 69 (83.1%) cases of live birth. Nine (9.8%) patients were lost to follow-up.

CONCLUSIONS

Both CMA and molecular testing for RD are important investigations in pregnancies with NT ≥ 3.5 mm. The use of genetic testing combined with fetal ultrasound examination provides valuable information that can influence pregnancy outcome, and provide recurrence risks, in this patient population. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Contribution of the Fetal Cardiac Axis and V-Sign Angle in First-Trimester Screening for Major Cardiac Defects

OBJECTIVE

To estimate the potential value of fetal assessment for the cardiac axis (CAx) and V-sign angle (VSA) in the first trimester in the prediction of fetal major cardiac defects.

METHODS

A cohort study was conducted from December 2015 to June 2016. Patients with singleton pregnancies and crown-rump length from 45 to 84 mm were recruited to undergo nuchal translucency sonography. The CAx on the 4-chamber view and the VSA on the 3-vessel and trachea view with Doppler mapping were measured. The estimated performance of different combinations of increased fetal nuchal translucency, CAx, and VSA in screening for major cardiac defects was examined.

RESULTS

The study population of fetuses included 30 fetuses with major cardiac defects and 1538 normal fetuses. The CAx and VSA were 30° to 60° and 30° to 40°, respectively, according to the 2.5th and 97.5th percentiles in normal fetuses. When cases of isolated septal wall defects and an isolated right aortic arch were excluded, nuchal translucency above the 95th percentile, an abnormal CAx, and an abnormal VSA were observed in 63.3% (19 of 30), 63.3% (19 of 30), and 66.7% (20 of 30) of fetuses with major cardiac defects, respectively, and in 4.6% (71 of 1538), 2.0% (30 of 1538), and 5.6% (86 of 1538) of those without cardiac defects. Either an abnormal CAx or VSA was found in 93.3% (28 of 30) of the fetuses with cardiac defects and in 7.3% (113 of 1538) of those without cardiac defects.

CONCLUSION

Assessment of the CAx and VSA is helpful in defining a population at risk for major cardiac defects in the first trimester.

Clinical experience with multiplex ligation-dependent probe amplification for microdeletion syndromes in prenatal diagnosis: 7522 pregnant Korean women

Background

Conventional cytogenetic analysis using G-band karyotyping has been the method of choice for prenatal diagnosis, accurately detecting chromosomal abnormalities larger than 5 Mb. However, the method is inefficient for detecting the submicroscopic deletions and duplications that are associated with malformations and mental retardation. This study evaluated the results of the multiplex ligation-dependent probe amplification (MLPA) P245 assay used for prenatal diagnosis in cases with unusual ultrasonographic findings or specifically where parents wanted to be tested. The objective was to compare the results from MLPA with those from conventional cytogenetic testing in order to determine their concordance and the additional diagnostic yield of MLPA over G-band karyotyping.

Results

Of the 7522 prenatal cases analyzed, 124 were found to have genomic imbalances (1.6%). Of those 124 cases, 41 had gene loss (33.6%), and 83 had gene gain (66.4%). Most of the cases with genomic imbalances (64.5%) showed no abnormal karyotype. In particular, all cases with a 4p16.3 deletion (Wolf-Hirschhorn syndrome) showed an abnormal karyotype, whereas all of those with a 22q11–13 deletion showed a normal karyotype. In most of the cases with pathogenic deletions, the indication for invasive prenatal testing was an increase in the nuchal translucency (NT) alone (51.2%). Other indications observed in the remaining cases were abnormal serum screening markers (14.6%), other ultrasonographic findings (9.8%), pregnancy through in vitro fertilization and fertility assistance (9.8%), and advanced maternal age(2.4%).

Conclusions

These results show that for fetuses with an enlarged NT or abnormal ultrasonographic findings and normal conventional karyotype, additional genetic investigation like molecular testing would be for identifying the microscopic genomic aberrations (microdeletions, microduplications) responsible for syndromic associations including structural anomalies and mental retardation.

Fetal exome sequencing: yield and limitations in a tertiary referral center

OBJECTIVE

To explore the indications for and diagnostic outcomes of fetal exome sequencing in a tertiary referral center.

METHODS

Between 2012 and 2017, 77 unrelated fetal samples from pregnancies referred to our center underwent exome sequencing. The cohort included 37 fetuses, 36 products of conception (from cases of pregnancy termination or intrauterine fetal death), one case with DNA from both the fetus and a previous termination of pregnancy, and three cases with DNA of unknown origin. Exome sequencing was performed on DNA extracted from amniocytes or fetal tissue and, in some cases, from parental peripheral blood. Indications, turnaround time, diagnostic rates and pregnancy outcomes were investigated. Diagnostic yield was analyzed according to consanguinity (yes or no), sample type (proband only, or trio or other) and referral indication (malformation or isolated nuchal translucency (NT)).

RESULTS

The most common indication for fetal exome sequencing was multiple malformations (21/77, 27%), followed by isolated brain malformation (15/77, 19%). Twelve (16%) fetuses were referred for isolated increased NT. Exome analysis was diagnostic for 16 fetuses (21%); when subclassified into fetal malformations vs isolated increased NT it became clear that exome analysis did not reveal any known or probable pathogenic variants in cases referred for isolated increased NT, whereas, among the remaining fetuses, a molecular diagnosis was reached in 16/65 (25%). Proband-only cases received a diagnosis more often than did cases that had trio exome sequencing.

CONCLUSIONS

Exome sequencing has the potential to provide molecular diagnoses in cases in which conventional prenatal cytogenetic testing is negative. Referral bias of consanguineous cases could account for the high diagnostic rate of proband-only sequencing. Syndrome-specific prognostic information enables parents to make informed decisions, whereas challenges include time limitations and variant interpretation in the setting of non-specific fetal findings. As we report only established disease-gene associations, further segregation and functional studies in a research setting are expected to increase significantly the diagnostic yield. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Association between unexplained thickened nuchal translucency and adverse pregnancy outcomes

OBJECTIVE

To determine the association between unexplained increased nuchal translucency (INT) and adverse pregnancy outcomes.

PATIENTS AND METHODS

The prospective database of our fetal down screening project was accessed to retrieve the records with NT measurement and complete follow-up. Pregnancies with pre-existing medical diseases, fetal chromosomal or structural abnormalities were excluded. The selected pregnancies were classified into the INT groups (> 95th percentile), the normal (< 95th percentile) group.

RESULTS

Of 6026 available for analysis (INT:277; and normal: 5749), the abortion rate was significantly higher in the INT group, 18/277 (6.5%) versus 55/5749 (1.0%); p < 0.001. After excluding 73 cases ending-up with abortion, a total of 5953 women were analyzed for final pregnancy outcomes, including 260 (4.4%), and 5693 (95.6%) in the study group (INT), and the control group (normal NT), respectively. The rates of pre-eclampsia (7.3 vs. 4.1%; p: 0.018), preterm birth (12.7 vs. 8.4%; p: 0.023), fetal growth restriction (11.5 vs. 7.6%; p: 0.032), and low birth weight (16.5 vs. 10.0%; p: 0.002) were slightly, but significantly higher in the study group.

CONCLUSIONS

INT in the first trimester is associated with significantly increased risk of abortion, fetal growth restriction, preterm birth, low birth weight and pre-eclampsia.

Application of noninvasive prenatal testing in pregnancies with fetal double bubble sign: Is it feasible?

OBJECTIVE

To evaluate the application of noninvasive prenatal testing as an alternative to invasive diagnostic testing in pregnancies with the double bubble sign.

METHODS

This was a retrospective analysis of 92 pregnancies with fetal double bubble identified by prenatal ultrasound, in which invasive diagnostic testing was performed for genetic investigations using quantitative fluorescence PCR and chromosomal microarray. Noninvasive prenatal testing was assumed to provide to patients for screening for the common aneuploidies.

RESULTS

Fetal trisomy 21 was detected in 8 of the 92 patients with prenatal double bubble. No other chromosomal anomalies or microscopic pathogenic copy-number variations (CNV) were found. Noninvasive prenatal testing could theoretically identified the affected pregnancies with trisomy 21 in this group with decreased number of invasive diagnostic testing.

CONCLUSIONS

Noninvasive prenatal testing could be recommended for genetic evaluation of the etiology of prenatal double bubble after thorough pretest counseling.

Increased nuchal translucency thickness and risk of neurodevelopmental disorders

OBJECTIVE

To investigate the association between fetal nuchal translucency (NT) thickness and neurodevelopmental disorders in euploid children.

METHODS

This study included 222 505 euploid children who had undergone routine first-trimester screening during fetal life. Children were divided according to prenatal NT into three groups: NT < 95^th percentile (n = 217 103 (97.6%)); NT 95^th -99^th percentile (n = 4760 (2.1%)); and NT > 99^th percentile (n = 642 (0.3%)). All children were followed-up to a mean age of 4.4 years. Information on diagnoses of intellectual disability, autism spectrum disorders (ASD), cerebral palsy, epilepsy and febrile seizures was obtained from national patient registries.

RESULTS

There was no excess risk of neurodevelopmental disorders among euploid children with first-trimester NT 95^th -99^th percentile. For children with NT > 99^th percentile, there were increased risks of intellectual disability (odds ratio (OR), 6.16 (95% CI, 1.51-25.0), 0.31%) and ASD (OR, 2.48 (95% CI, 1.02-5.99), 0.78%) compared with children with NT < 95^th percentile (incidence of 0.05% for intellectual disability and 0.32% for ASD), however, there was no detected increase in the risk of cerebral palsy (OR, 1.91 (95% CI, 0.61-5.95), 0.47%), epilepsy (OR, 1.51 (95% CI, 0.63-3.66), 0.78%) or febrile seizures (OR, 0.72 (95% CI, 0.44-1.16), 2.65%).

CONCLUSIONS

In a large unselected cohort of euploid children, there was no increased risk of neurodevelopmental disorders among those with a first-trimester NT 95^th -99^th percentile. Among euploid children with first-trimester NT > 99^th percentile, there were increased risks of intellectual disability and ASD, but the absolute risk was reassuringly low (< 1%). Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Pregnancy Outcome of Abnormal Nuchal Translucency: A Systematic Review

INTRODUCTION

Nuchal Translucency (NT) is the sonographic form of subcutaneous gathering of liquid behind the foetal neck in the first trimester of pregnancy. There is association of increased NT with chromosomal and non-chromosomal abnormalities.

AIM

The purpose of this systemic review was to review the pregnancy outcome of abnormal nuchal translucency.

MATERIALS AND METHODS

The present systematic review was conducted by searching English language articles from sources such as International Medical Sciences, Medline, Web of science, Scopus, Google Scholar, PubMed, Index Copernicus, DOAJ, EBSCO-CINAHL. Persian articles were searched from Iranmedex and SID sources. Related key words were "outcome", "pregnancy", "abnormal", and "Nuchal Translucency" (NT). All, randomized, descriptive, analytic-descriptive, case control study conducted during 1997-2015 were included.

RESULTS

Including duplicate articles, 95 related articles were found. After reviewing article titles, 30 unrelated article and abstracts were removed, and 65 articles were evaluated of which 30 articles were duplicate. Finally 22 articles were selected for final analysis. Exclusion criteria were, case studies and reports and quasi experimental designs. This evaluation has optioned negative relationship between nuchal translucency and pregnancy result. Rate of cardiac, chromosomal and other defects are correlated with increased NT≥2.5mm. Cardiac disease which were associated to the increased NT are heart murmur, systolic organic murmur, Atrial Septal Defect (ASD), Ventricular Septal Defect (VSD), tricuspid valve insufficiency and pulmonary valve insufficiency, Inferior Vena Cava (IVC) and Patent Ductus Arteriosus (PDA). The most common problems that related with increased NT were allergic symptoms.

CONCLUSION

According to this systematic review, increased NT is associated with various foetal defects. To verify the presence of malformations, birth defect consultations with a perinatologist and additional tests are required.

How necessary is to analyze PTPN11 gene in fetuses with first trimester cystic hygroma and normal karyotype?

Cystic hygroma (CH) is a vascular-lymphatic malformation and can occur either as an isolated finding or as a part of a syndrome. The incidence of CH is about 1:1000-1:6000 births. Ultrasonographic diagnosis of CH is usually obtained in the first trimester, and the lesion can appear in septated or non-septated forms. Increased nuchal translucency and CH have been associated with a wide range of structural and genetic abnormalities. Most of CHs are associated with a number of chromosomal abnormalities especially Trisomy 21, 13, 18 and Turner syndrome. Besides, the associations between CH and non-chromosomal syndromes were also reported and Noonan Syndrome (NS) is one of the leading causes. Approximately 50% of NS cases are caused by mutations in the PTPN11 gene. A novel PTPN11 mutation defined in two separate fetuses with CH and associated with NS phenotype is being reported here.

Non-invasive prenatal testing for aneuploidy and beyond: challenges of responsible innovation in prenatal screening

This paper contains a joint ESHG/ASHG position document with recommendations regarding responsible innovation in prenatal screening with non-invasive prenatal testing (NIPT). By virtue of its greater accuracy and safety with respect to prenatal screening for common autosomal aneuploidies, NIPT has the potential of helping the practice better achieve its aim of facilitating autonomous reproductive choices, provided that balanced pretest information and non-directive counseling are available as part of the screening offer. Depending on the health-care setting, different scenarios for NIPT-based screening for common autosomal aneuploidies are possible. The trade-offs involved in these scenarios should be assessed in light of the aim of screening, the balance of benefits and burdens for pregnant women and their partners and considerations of cost-effectiveness and justice. With improving screening technologies and decreasing costs of sequencing and analysis, it will become possible in the near future to significantly expand the scope of prenatal screening beyond common autosomal aneuploidies. Commercial providers have already begun expanding their tests to include sex-chromosomal abnormalities and microdeletions. However, multiple false positives may undermine the main achievement of NIPT in the context of prenatal screening: the significant reduction of the invasive testing rate. This document argues for a cautious expansion of the scope of prenatal screening to serious congenital and childhood disorders, only following sound validation studies and a comprehensive evaluation of all relevant aspects. A further core message of this document is that in countries where prenatal screening is offered as a public health programme, governments and public health authorities should adopt an active role to ensure the responsible innovation of prenatal screening on the basis of ethical principles. Crucial elements are the quality of the screening process as a whole (including non-laboratory aspects such as information and counseling), education of professionals, systematic evaluation of all aspects of prenatal screening, development of better evaluation tools in the light of the aim of the practice, accountability to all stakeholders including children born from screened pregnancies and persons living with the conditions targeted in prenatal screening and promotion of equity of access.

Changing to NIPT as a first-tier screening test and future perspectives: opinions of health professionals

OBJECTIVE

The aim of this study was to investigate health professionals' opinions toward offering noninvasive prenatal testing (NIPT) as first-tier screening test regardless of pregnant women's risk, and toward a potential broader range of disorders.

METHODS

A questionnaire completed by obstetric health professionals (n = 240) after an in-service NIPT training in the West and North of the Netherlands.

RESULTS

The majority (72%) of respondents favored replacing first-trimester combined test (FCT) by NIPT, although 43% preferred to maintain nuchal translucency measurement. Many respondents believed that replacing FCT by NIPT would only have advantages (57%), would lead to more pregnant women opting for prenatal testing (69%), and would simplify counseling (47%). Differences in attitudes toward counseling between health professionals were observed. When considering NIPT to screen for broader range of disorders, the majority (92%) thought that this should include disorders characterized by neonatal death, whereas 52% of the respondents favored testing for fetomaternal risk factors. Overall, 46% thought screening should be offered as a fixed list of disorders.

CONCLUSION

Most health professionals favor NIPT instead of FCT but prefer to maintain nuchal translucency measurement. If NIPT becomes available as a first-tier screening test, attention remains necessary to ensure that pregnant women make well-informed decisions in line with the aim of prenatal screening.

Advantages and Disadvantages of Different Implementation Strategies of Non-Invasive Prenatal Testing in Down Syndrome Screening Programmes

BACKGROUND

Implementation of non-invasive prenatal testing (NIPT) in Down syndrome screening programmes requires health policy decisions about its combination with other tests and its timing in pregnancy.

AIM

Our aim was to aid health policy decision makers by conducting a quantitative analysis of different NIPT implementation strategies.

METHODS

Decision trees were created to illustrate all plausible alternatives in a theoretical cohort of 100,000 pregnant women in five screening programmes: classical screening by the first-trimester combined test (FCT), pre-selection of high-risk women prior to NIPT by the FCT, NIPT as the first screening test at 10 weeks and at 13 weeks, and the simultaneous conductance of NIPT and the FCT.

RESULTS

Pre-selection by FCT prior to NIPT reduces the number of amniocenteses to a minimum because of a reduction of false-positive NIPT results. If NIPT is the first screening test, it detects almost all fetal Down syndrome cases. NIPT at 10 weeks reassures women early in pregnancy, while NIPT at 13 weeks prevents unnecessary tests due to spontaneous miscarriages and allows for immediate confirmation by amniocentesis.

CONCLUSION

Every implementation strategy has its advantages and disadvantages. The most favourable implementation strategy may be NIPT as the first screening test at 13 weeks, offering the most accurate screening test for Down syndrome, when the risk for spontaneous miscarriage has declined remarkably and timely confirmation by amniocentesis can be performed.

Risk of critical congenital heart defects by nuchal translucency norms

OBJECTIVE

The purpose of this study was to compare the performance of first-trimester nuchal translucency (NT) cutoff of ≥3.5 mm with NT percentiles that were calculated for crown-rump length to identify fetuses with critical congenital heart defects (CCHDs).

STUDY DESIGN

This was a population-level study of singleton pregnancies in California with NT measurements performed between 11 and 14 weeks of gestation. Eligible cases were those that resulted in live births from 2009-2010 and had information about the presence or absence of CCHDs available in the hospital discharge records through age 1 year (n = 76,089). Logistic binomial regression methods were used to compare the rate of CCHDs by an NT percentile for crown-rump length and millimeter cutpoints.

RESULTS

Compared with fetuses with an NT measurement of <90th percentile, fetuses with an NT of ≥99th percentile were >5 times as likely to have a CCHD (1.3% vs 0.2%; relative risk, 5.66; 95% confidence interval, 3.19-10.04) and fetuses with an NT measurement ≥3.5 mm were >12 times as likely to have a CCHD (2.8% vs 0.2%; relative risk, 12.28; 95% confidence interval, 5.11-29.51). NT ≥99th percentile had a sensitivity of 5.8% and a specificity of 98.9% for the detection of CCHDs compared with 2.6% and 99.8% for NT ≥3.5 mm.

CONCLUSION

Results show that NT measurements of ≥99th percentile and ≥3.5 mm are not equivalent and that substantial risk for CCHD extends to the less restrictive ≥99th percentile cutpoint. Data suggest that the use of this cutpoint compared with the current standard could double the number of CCHDs that are identified based on NT risk.

Effects of exogenous progesterone on fetal nuchal translucency: an observational prospective study

OBJECTIVE

Nuchal translucency (NT) seen ultrasonographically at 11-14 weeks' gestation is a sensitive marker for Down syndrome. Despite its important role for Down syndrome screening, its use is still considered controversial due to high false-positive rates. We speculated that progesterone could lead to abnormal blood flow patterns and, subsequently, to increased NT. Our primary endpoint was to evaluate the effects of exogenous progesterone on NT thickness compared to controls. The secondary endpoint was to evaluate these effects in a subgroup at low risk for fetal aneuploidies, identifying the strongest factors influencing NT variation. The tertiary endpoint was to evaluate, within the treatment group, if there is any difference in NT according to the type of progesterone administered, route of administration, and dose regimen.

STUDY DESIGN

All women who came to measure NT at 11-14 weeks' gestation (crown-rump length between 45-84 mm) were considered eligible. We divided patients into 2 groups: women receiving exogenous progesterone and controls. Afterwards, 3 NT scans were performed for each case, and the largest value, accurate to 2 decimal points, was recorded.

RESULTS

In all, 3716 women were enrolled and analyzed. In a crude analysis, NT (P < .05) increased in the exogenous progesterone group. The same results were obtained in the low-risk group (P < .05). The factorial analysis of variance model confirmed a correlation between altered NT and gestational age (P < .0001) and progesterone exposure (P < .05). The characteristics of treatment (route, formulation, dose) were examined separately and no statistically significant differences among the subgroups were observed.

CONCLUSION

Exogenous progesterone increases NT.

Increased first-trimester nuchal translucency associated with thanatophoric dysplasia type 1

Thanatophoric dysplasia (TD) is the most frequent form of lethal skeletal dysplasia. Prenatal diagnosis is commonly accomplished in the second-trimester scan, but occasionally TD is found to be associated with increased nuchal translucency (NT) at first-trimester screening for aneuploidies. TD may not be clearly distinguished from the other skeletal dysplasias. A definite diagnosis can be established by molecular genetic analysis to find out the abnormal mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. We reported a case of TD type 1 detected by first-trimester NT measurement, and confirmed by molecular analysis of FGFR3 gene using high-resolution melting analysis.

Chromosomal microarray in fetuses with increased nuchal translucency

OBJECTIVE

To assess the clinical value of using high-resolution chromosomal microarray (CMA) for the examination of genomic imbalances in prenatal uncultured chorionic villus samples from fetuses with increased nuchal translucency (NT) and a normal quantitative fluorescent polymerase chain reaction (QF-PCR) result, in a clinical setting in which more than 95% of pregnant women receive first-trimester combined screening.

METHODS

From January 2013 to July 2014, we included 132 chorionic villus samples from consecutive ongoing pregnancies, with fetal NT ≥ 3.5  mm at 11-13 weeks' gestation, from obstetric units (publicly funded healthcare) in Central and North Denmark Regions. DNA was extracted directly from the samples and examined with QF-PCR (n = 132) and 180 kb oligonucleotide array-based comparative genomic hybridization (n =  94).

RESULTS

In 38 cases, aneuploidies for chromosomes 18, 21 or X, or triploidy, were detected by QF-PCR. Among the 94 cases with a normal QF-PCR result, we detected pathogenic copy number variants (CNVs) by CMA in 12 fetuses (12.8% (95% CI, 7.5-21.0%)). In an additional three (3.2%) cases, CNVs with uncertain clinical significance were detected.

CONCLUSION

CMA is a valuable diagnostic technique in pregnancies with isolated fetal NT ≥ 3.5 mm.

Risk of selected structural abnormalities in infants after increased nuchal translucency measurement

OBJECTIVE

We sought to examine the association between increased first-trimester fetal nuchal translucency (NT) measurement and major noncardiac structural birth defects in euploid infants.

STUDY DESIGN

Included were 75,899 singleton infants without aneuploidy or critical congenital heart defects born in California in 2009 through 2010 with NT measured between 11-14 weeks of gestation. Logistic binomial regression was employed to estimate relative risks (RRs) and 95% confidence intervals (CIs) for occurrence of birth defects in infants with an increased NT measurement (by percentile at crown-rump length [CRL] and by ≥3.5 mm compared to those with measurements <90th percentile for CRL).

RESULTS

When considered by CRL adjusted percentile and by measurement ≥3.5 mm, infants with a NT ≥95th percentile were at risk of having ≥1 major structural birth defects (any defect, RR, 1.6; 95% CI, 1.3-1.9; multiple defects, RR, 2.1; 95% CI, 1.3-3.4). Infants with a NT measurement ≥95th percentile were at particularly high risk for pulmonary, gastrointestinal, genitourinary, and musculoskeletal anomalies (RR, 1.6-2.7; 95% CI, 1.1-5.4).

CONCLUSION

Our findings demonstrate that risks of major pulmonary, gastrointestinal, genitourinary, and musculoskeletal structural birth defects exist for NT measurements ≥95th percentile. The ≥3-fold risks were observed for congenital hydrocephalus; agenesis, hypoplasia, and dysplasia of the lung; atresia and stenosis of the small intestine; osteodystrophies; and diaphragm anomalies.

Association of non-invasive prenatal testing and chromosomal microarray analysis for prenatal diagnostics

The purposes of this study is to examine possibility to use combination of non-invasive prenatal testing (NIPT) and chromosomal microarray analysis (CMA) for prenatal diagnostics and their advantages between combined first-trimester screen with confirmation by karyotyping of CVS or amniocytes. A total of 1968 pregnant women, in this study, have undergone prenatal screening and/or diagnostic tests. NIPT is more suitable and efficient for the detection of aneuploidy. However, this test has limitations for detection deletions/duplications. Use of CMA for confirmation of some NIPT findings or as first test for women with ultrasound abnormalities can detect small imbalances in chromosomes. Combination of NIPT and CMA allows a higher prenatal detection of chromosomal abnormalities.

Extremely large nuchal translucency measurement predicts adverse pregnancy outcome

A prospective study was conducted to determine the outcome of pregnancies with 1st trimester nuchal translucency measurement of ≥ 6.5 mm. The risk of fetal abnormalities increases with enlarging nuchal translucency, being around 45% with a measurement of ≥ 6.5 mm. A total of 27,144 women with singleton pregnancies participated in the combined Down syndrome screening within the public healthcare system in Northern Finland. The study period was 1 May 2002 to 31 May 2009. The nuchal translucency measurement was ≥ 6.5 mm in 16 cases (0.06%). Pregnancy outcome was normal in one case (6.3%). The risk of abnormality was higher in our study than reported in the literature. According to our study, immediate diagnostic tests should be offered after an nuchal translucency measurement of ≥ 6.5 mm. We should also consider analysis of fetal micro-deletions associated with certain syndromes.

Is there any relationship between adverse pregnancy outcome and first trimester nuchal translucency measurements in normal karyotype fetuses?

AIM

This study aims to research whether there is a relationship between first trimester nuchal translucency (NT) measurements and pregnancy complications such as gestational diabetes mellitus (GDM), gestational hypertension (GHT), intrauterine growth restriction (IUGR) and oligohydramnios.

METHOD

This study included 225 singleton pregnancies attending Canakkale Onsekiz Mart University Obstetrics and Gynecology clinic for all monitoring and examinations, and gave birth at our clinic between January 2011 and December 2012. Data sources were clinical records and the hospital's automation system, and the study was planned as retrospective cohort. NT measurement was made between 10 weeks 3 days and 13 weeks 6 days gestation. For data analysis, the chi-square, Mann-Whitney U test and Spearman correlation were used.

RESULTS

Of pregnancies, in the study, 5 (2.2%) developed GDM, 6 (2.6%) developed GHT, 2 (0.89%) developed IUGR and 10 (4.4%) developed oligohydramnios. There was no correlation identified between NT measurements and development of GDM, GHT, IUGR and oligohydramnios.

CONCLUSION

There was no relationship found between first trimester NT measurements and complications that could develop in pregnancy. For the first time in the literature, NT and oligohydramnios were studied and no relationship was observed.

Detection of structural abnormalities in the first trimester using ultrasound

During the past 25 years, embryonic and early fetal ultrasound and diagnosis have increasingly gained attention in pregnancy care. Modern high-frequency ultrasound transducers make it possible to obtain detailed images of the early conceptus and its organs, and thus move part of the anatomy and anomaly scan from the second to the first trimester. Today, detection of embryonic and fetal structural abnormalities in the first trimester has frequently been reported. One has to distinguish between diagnosis during the early period until about 10 weeks when the embryo or early fetus is small and transvaginal ultrasound is applied, and diagnosis during the late period at the nuchal translucency screening, usually carried out using transabdominal ultrasound. Early first-trimester abnormalities are often diagnosed by chance on clinical indications, whereas late first-trimester diagnoses are the result of systematic screening using ultrasound markers.

The 'thousand-dollar genome': an ethical exploration

Sequencing an individual's complete genome is expected to be possible for a relatively low sum 'one thousand dollars' within a few years. Sequencing refers to determining the order of base pairs that make up the genome. The result is a library of three billion letter combinations. Cheap whole-genome sequencing is of greatest importance to medical scientific research. Comparing individual complete genomes will lead to a better understanding of the contribution genetic variation makes to health and disease. As knowledge increases, the 'thousand-dollar genome' will also become increasingly important to healthcare. The applications that come within reach raise a number of ethical questions. This monitoring report addresses the issue.

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.

Association of early-preterm birth with abnormal levels of routinely collected first- and second-trimester biomarkers

OBJECTIVE

The purpose of this study was to examine the relationship between typically measured prenatal screening biomarkers and early-preterm birth in euploid pregnancies.

STUDY DESIGN

The study included 345 early-preterm cases (<30 weeks of gestation) and 1725 control subjects who were drawn from a population-based sample of California pregnancies who had both first- and second-trimester screening results. Logistic regression analyses were used to compare patterns of biomarkers in cases and control subjects and to develop predictive models. Replicability of the biomarker early-preterm relationships that was revealed by the models was evaluated by examination of the frequency and associated adjusted relative risks (RRs) for early-preterm birth and for preterm birth in general (<37 weeks of gestation) in pregnancies with identified abnormal markers compared with pregnancies without these markers in a subsequent independent California cohort of screened pregnancies (n = 76,588).

RESULTS

The final model for early-preterm birth included first-trimester pregnancy-associated plasma protein A in the ≤5th percentile, second-trimester alpha-fetoprotein in the ≥95th percentile, and second-trimester inhibin in the ≥95th percentile (odds ratios, 2.3-3.6). In general, pregnancies in the subsequent cohort with a biomarker pattern that were found to be associated with early-preterm delivery in the first sample were at an increased risk for early-preterm birth and preterm birth in general (<37 weeks of gestation; adjusted RR, 1.6-27.4). Pregnancies with ≥2 biomarker abnormalities were at particularly increased risk (adjusted RR, 3.6-27.4).

CONCLUSION

When considered across cohorts and in combination, abnormalities in routinely collected biomarkers reveal predictable risks for early-preterm birth.

Crown-rump length discordance and adverse perinatal outcome in twins: analysis of the Southwest Thames Obstetric Research Collaborative (STORK) multiple pregnancy cohort

OBJECTIVE

Evidence for the role of first-trimester ultrasound in predicting outcome in twin pregnancies is conflicting. The aim of this study was to determine the association between crown-rump length (CRL) discordance and adverse perinatal outcome in twin pregnancies.

METHODS

This was a retrospective study of all twin pregnancies of known chorionicity from a large regional cohort over a 10-year period. Terminations of pregnancy, cases with fetal or chromosomal abnormalities and monoamniotic pregnancies were excluded. Receiver-operating characteristics (ROC) curve and logistic regression analyses were performed to evaluate the association between CRL discordance and stillbirth, neonatal mortality, intrauterine growth restriction, preterm birth (PTB) at < 34 weeks' gestation and birth weight (BW) and ultrasound estimated fetal weight (EFW) discordance of ≥ 25%.

RESULTS

A total of 2155 twin pregnancies were analyzed, of which 420 were monochorionic (MC) and 1735 dichorionic (DC). There were 42 fetal losses before 24 weeks' gestation and 23 perinatal deaths. CRL discordance was poorly predictive for fetal loss at < 24 weeks (area under the ROC curve (AUC), 0.54 (95% CI, 0.46-0.62)), perinatal loss (AUC, 0.52 (95% CI, 0.41-0.64)), BW discordance (AUC, 0.61 (95% CI, 0.56-0.65)), BW < 5(th) centile (AUC, 0.56 (95% CI, 0.53-0.59)), EFW discordance (AUC, 0.55 (95% CI, 0.51-0.60)) and PTB at < 34 weeks (AUC, 0.50 (95% CI, 0.47-0.54)). Overall mortality was significantly higher in MC (5.0%) than in DC (2.6%) twins (P = 0.016). Logistic regression analysis demonstrated that chorionicity (odds ratio 2.09 (95% CI, 1.06-4.10); P = 0.033) independently contributed to determining mortality, while CRL discordance (P = 0.201) did not. Adjusting for chorionicity did not improve the detection of adverse outcomes using CRL discordance.

CONCLUSION

In the absence of aneuploidy or structural fetal abnormality, CRL discordance is of poor predictive value for adverse perinatal outcome in both MC and DC twin pregnancies. CRL discordance should not be used routinely to identify twin pregnancies at high risk of adverse perinatal outcome.