First-trimester nuchal translucency and cardiac septal defects in fetuses with trisomy 21

Trends in the prenatal diagnosis of trisomy 21 show younger maternal age and shift in the distribution of congenital heart disease over a 20-year period

Prenatal testing has changed greatly over the past two decades, which may affect the diagnosis of congenital heart disease (CHD) in Down syndrome. The present study aimed to analyze changes in the prevalence and distribution of CHD diagnosed via ultrasonography and fetopathology in 462 fetuses with trisomy 21 between two consecutive 10-year periods (1999-2018), as well as the associations between CHDs, ultrasound markers, and extracardiac malformations. Overall, the frequency of cardiovascular malformations in trisomy 21 was 27.7 and 26.5%, and ultrasound identified 70 and 62% of CHDs during these periods. A profound increase in first-trimester ultrasound findings and associated anomalies with CHDs (ventricular septal defect, Tetralogy of Fallot) since 2009 were observed. Second-trimester nonstructural heart abnormalities were associated with ultrasound anomalies (74%) and major extracardiac malformations (42.9%). During both study periods, mothers carrying fetuses with CHD were significantly younger than those without CHD (p = 0.038, p = 0.009, respectively). Comparing the two 10-year periods, there were no changes in the prevalence and detection of CHDs. Trend analysis revealed that, although the frequency of CHD remained stable, the diagnostic spectrum had shifted between the study periods. Detection of nonstructural heart abnormalities necessitates detailed follow-up for cardiac/extracardiac malformations and chromosomal disorders.

[Contribution of array CGH in the management of fetal nuchal translucency]

OBJECTIVES

Increased nuchal translucency and cystic hygroma have a neonatal prognosis, when the karyotype is normal, which depends on the findings during the medical follow-up. Array comparative genomic hybridization (aCGH) has been systematically included in this follow-up by prenatal diagnosis teams. There are no guidelines and little information on the advantages of carrying out this test systematically. The aim of our study is to evaluate the contribution of the aCGH in the medical follow-up.

METHODS

Fifty-one patients were included during 18 months and followed till the end of their pregnancy in prenatal diagnosis centers in Brest and Amiens. Inclusion criterion was a nuchal translucency above 3,5mm on the first trimester ultrasound. A fetal DNA ChromoQuant and aCGH analysis on chorionic villi sampling, and an ultrasound at 18 weeks of gestation were performed during the follow-up.

RESULTS

The aCGH was decisive in only 2 cases. The ultrasound at 18 weeks gestation seemed to be more sensible in the detection of an abnormality. When the aCGH relieved an abnormality, the ultrasound permitted already to detect the presence of a deformity. In 10 cases, the aCGH could not be interpreted on the chorionic villi sampling. In 9 cases, an amniocentesis was performed in order to obtain this result.

CONCLUSION

Given the results of this study, the aCGH was rarely determinant or decisive on the realization of a therapeutic abortion. These elements make us reflect on the necessity of maintaining this test before 14 weeks of gestation or propose it as a second-line test after the ultrasound shows signs at 18weeks of gestation.

First trimester ultrasound assessment for fetal aneuploidy

Screening tests for trisomy 21 have gradually become more refined and now involve complex statistical models that combine demographic, biophysical, and biochemical parameters to produce individualized risk estimates for pregnant women. An understanding of the evolution of the principles, methods, and statistical techniques applied to Down syndrome screening is valuable as these processes can be transferred to other, more prevalent, adverse pregnancy outcomes. First trimester ultrasound forms the foundation of this process.

First Trimester Ultrasound in Prenatal Diagnosis-Part of the Turning Pyramid of Prenatal Care

First-trimester sonographic assessment of the risk of chromosomal abnormalities is routinely performed throughout the world, primarily by measuring fetal nuchal translucency thickness between 11–13 weeks’ gestation, combined with assessment of serum markers. The development of high-frequency transvaginal transducers has led to improved ultrasound resolution and better visualization of fetal anatomy during the first-trimester. Continuous improvement in ultrasound technology allows a thorough detailed assessment of fetal anatomy at the time of the nuchal translucency study. Using transabdominal or transvaginal sonography, or a combination of both approaches, it is now possible to diagnose a wide range of fetal anomalies during the first trimester. Multiple studies reported early diagnosis of major fetal anomalies after demonstrating the association of increased nuchal translucency thickness with structural defect in chromosomally normal and abnormal fetuses. Normal sonographic findings provide reassurance for women at high risk while detection of fetal malformation during the first trimester enables discussion and decisions about possible treatments and interventions, including termination of pregnancy, during an early stage of pregnancy.

Outcome and requirement for surgical repair following prenatal diagnosis of ventricular septal defect

OBJECTIVE

To document outcome following prenatal diagnosis of ventricular septal defects (VSDs), particularly associated anomalies and the requirement for surgical closure of the defect.

METHODS

All cases of prenatal diagnosis of a VSD made by fetal cardiologists at a tertiary fetal medicine referral center in the period January 2002 to December 2011 were extracted from our database. Data regarding fetal cardiac diagnosis, extracardiac anomalies, nuchal translucency thickness and karyotype were noted.

RESULTS

A total of 171 cases fulfilled our selection criteria. Of these, 69% were diagnosed with a perimembranous VSD and 31% with a muscular defect. The median gestational age at diagnosis was 21 + 6 (range, 12 + 0 to 37 + 3) weeks. Owing to severe extracardiac or genetic conditions, pregnancy resulted in intrauterine death or termination in 49% cases, and postnatal death occurred in 9% of cases. Seventy-two babies were liveborn, and were regarded as potential surgical candidates if hemodynamics suggested that surgery was indicated. Surgical closure of the VSD proved necessary in 50% of the patients with a perimembranous VSD and 13% of those with a muscular VSD. All patients operated on survived surgical repair. No karyotypic abnormalities were identified in fetuses with VSDs that had normal first-trimester screening and no other sonographic abnormalities.

CONCLUSIONS

A high proportion of VSDs diagnosed during fetal life (29%) require postnatal surgical intervention. The assessment of hemodynamic significance from fetal echocardiography is imperfect. The presence of extracardiac abnormalities or abnormal results on first-trimester screening has a major impact on the incidence of karyotypic abnormalities in affected fetuses. This should inform discussions with parents about invasive testing.

Simplified protocol of nuchal translucency measurement: Is it still effective?

Objective

Nuchal translucency (NT) is the most powerful screening tool for Down syndrome and congenital cardiac anomaly, therefore strict guidelines were established to get accurate NT values. However, to stick to the guideline in all pregnant women is time-consuming and superfluous in majority of low risk population. We undertook this study to investigate whether the simplified protocol enables to select low risk group and is effective in them even if we skip the suggested NT measurement.

Methods

NT and crown-rump length (CRL) were measured prospectively. First, CRL was measured in the ordinary view that was mid-sagittal section of fetus in neutral position, and NT was measured at the same frozen screen (first measured value, 1MV). Then, NT was measured again according to the Fetal Medicine Foundation (FMF) guideline (second measured value, 2MV).

Results

There was good correlation between 1MV and 2MV in each case (r = 0.83, P < 0.001). All of the NT values over the 95th percentile in 2MV also belonged to over the 95th percentile in 1MV. NT value of 2 mm in 1MV could be used as a cut-off to obtain over the 95th percentile 2MV by receiver operating characteristic curve (sensitivity 100%, specificity 80.5%). The proportion of 1MV ≥ 2 mm was only 23.8% of all cases, namely we had only to measure 2MV in 23.8% patients. Every 95th percentile or more 2MV could be detected with this simplified protocol.

Conclusion

If NT is less than 2 mm at ordinary CRL view, we may skip suggested NT measurement according to FMF guideline.

Male-to-female gender ratio in fetuses with increased nuchal translucency

OBJECTIVE

To describe gender distribution in fetuses with increased nuchal translucency (NT) measurements.

METHODS

All fetuses with mild (2.5-2.9 mm) and moderate (3.0-3.5 mm) NT enlargement at 12.0-12.6 weeks gestation were studied. The Z test for proportions was used to compare the gender distribution of this study group to that of all babies born at Roosevelt Hospital in 2008, and to compare the gender distributions of the subgroups.

RESULTS

5109 patients received screening at 12.0-12.6 weeks gestation. 44 fetuses had mild and 28 had moderate enlargement, with a male-to-female ratio of 3.8:1.0, much higher than the 1.06:1.0 ratio among total births at Roosevelt Hospital in 2008 (p < 0.0001). Male-to-female ratio was 7.8:1.0 in fetuses with mild and 1.8:1.0 with moderate NT enlargement (p = 0.03). Among fetuses with mild NT enlargement, 3 males had aneuploidy; among those with moderate enlargement, 6 fetuses had aneuploidy, 3 males and 3 females. Seven pregnancies with aneuploidy were voluntarily terminated. All pregnancies carried to term were healthy.

CONCLUSIONS

More males than females had mild NT enlargement on first-trimester screening, but unless aneuploidy was detected they had normal birth outcomes. A slightly larger NT may be normal in males, while indicating possible fetal abnormalities in females.

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.

Prenatally detectable congenital heart defects in fetuses with Down syndrome

OBJECTIVE

To document the incidence of congenital heart defects (CHD) that are detectable echocardiographically in the fetus with trisomy 21 and the relationship with nuchal translucency, fetal sex and ethnicity.

METHODS

Data on fetuses with a karyotypic diagnosis of trisomy 21 were collected between January 2002 and March 2010. The data were analyzed for the gestational age at examination, maternal age, reason for referral for fetal echocardiography, cardiac diagnosis, fetal sex, ethnicity and outcome.

RESULTS

Of 917 fetuses with trisomy 21, 487 had a diagnostic echocardiogram. Cardiac examination was performed before 14 weeks' gestation in 75% of cases. The main reasons for referral were increased nuchal translucency (NT) in 76% of cases, suspected cardiac abnormality in 15% and an extracardiac anomaly in 6%. Structural CHD was found in 164/487 (34%), or 98/412 (24%) if those referred for suspected CHD are removed from the analysis. The most common diagnosis was atrioventricular septal defect (AVSD) (115/487, 24%). The ratio of female to male fetuses with AVSD was 29%:18% (P = 0.003). There was no difference in the incidence of AVSD with ethnicity. The pregnancy continued in 36 cases, but three were lost to follow-up; of the known outcomes there were 10 intrauterine deaths, six of which had structural heart disease, and 23 live births, 15 of which had CHD.

CONCLUSION

Most fetuses (66-76%) with trisomy 21 have a structurally normal heart on echocardiography. The presence of structural CHD was not associated with increased NT. The increased incidence of AVSD in females was confirmed in our study, although an ethnic difference could not be confirmed. CHD does not appear to increase the chance of spontaneous intrauterine loss in ongoing pregnancies.

Has prenatal screening influenced the prevalence of comorbidities associated with Down syndrome and subsequent survival rates?

OBJECTIVES

With this study we aimed to compare survival rates for children with Down syndrome in 2 time periods, 1 before prenatal screening (1988-1990) and 1 contemporaneous with screening (1998-2000), and to examine the frequency of comorbidities and their influence on survival rates.

METHODS

Record-linkage was performed between the population-based Victorian Birth Defects Register and records of deaths in children up to 15 years of age collected under the auspice of the Consultative Council on Obstetric and Pediatric Mortality and Morbidity. Cases of Down syndrome were coded according to the presence or absence of comorbidities by using the International Classification of Diseases, Ninth Revision classification of birth defects. Kaplan-Meier survival functions and log rank tests for equality of survival distributions were performed.

RESULTS

Of infants liveborn with Down syndrome in 1998-2000, 90% survived to 5 years of age, compared with 86% in the earlier cohort. With fetal deaths excluded, the proportion of isolated Down syndrome cases in the earlier cohort was 48.7% compared with 46.1% in the most recent cohort. In 1988-1990 there was at least 1 cardiac defect in 41.1% of cases and in 45.4% in 1998-2000. There was significant variation in survival rates for the different comorbidity groupings in the 1988-1990 cohort, but this was not so evident in the 1998-2000 cohort.

CONCLUSIONS

Survival of children with Down syndrome continues to improve, and there is an overall survival figure of 90% to at least 5 years of age. It is clear from this study that prenatal screening technologies are not differentially ascertaining fetuses with Down syndrome and additional defects, because there has been no proportional increase in births of isolated cases with Down syndrome.

Evidence of genetic underexpression in chorionic villi samples of euploid fetuses with increased nuchal translucency at 10–11 weeks' gestation

OBJECTIVE

To retrospectively investigate whether the genetic profile from chorionic villous sampling (CVS) found in euploid fetuses with increased NT differs from matched controls.

STUDY DESIGN

We employed cDNA microarray technology to characterize and compare the gene expression profile of chorionic villous tissues (which encompass the trophoblast and inner mesenchymal core) belonging to four singleton male fetuses with increased NT at 10-11 weeks' gestation. A pool of four normal chorionic villous tissues belonging to four respective fetuses, matched for gestational age and gender, was used as controls.

RESULTS

In euploid fetuses, we found several underexpressed genes, possibly involved in mechanisms associated with the abnormal NT thickness. All these genes are likely to belong to the mesenchymal core of the villus that originates from the extraembryonic mesoderm, and thus might be closely representative of the embryonic genetic profile. They include: (1) genes of embryonic development and differentiation such as Endothelin 3 (EDN3) and secreted frizzled-related protein 4 (SFRP4); (2) genes of the extracellular matrix (ECM) metabolism such as tissue inhibitor of metalloproteinase1 (TIMP1), and disintegrin-like and matrix metalloproteinase (MMP) (reprolysin type) with thrombospondin type 1 Motif or ADAMTS2, exostoses (multiple)-like 1 (EXTL1), heparan sulfate (HS) 6-O-sulfotransferase 1 or HS6ST1, fibronectin 1 (FN1) and Integrin Alpha 10 (ITGA10) involved in HS and proteoglycan bio-synthesis, ECM synthesis and cell-matrix adhesion; (3) genes involved in vessel formation and differentiation such as angiogenic factor (VG5Q), and in blood pressure control and muscle contraction, like Endothelin 3 or EDN3 and sarcolemma associated protein (SLMAP). Such lower expressions of the villous tissues might be related to an immature genetic profile of the embryo development as well as abnormal regulation of ECM bio-synthesis and/or improper vessel growth and blood pressure control. Also, the results partially support the theories proposed for NT enlargement such as altered composition of ECM and abnormal/delayed development of the circulatory system.

CONCLUSIONS

Abnormal extraembryonic genetic expression is found at 10-11 weeks' gestation in euploid fetuses with increased NT. If both extra- and intraembryonic mesoderms express the same genetic alterations, then microarray analyses on CVS could be used to screen several mesoderm-derivate anomalies.

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.

First-trimester fetuses with increased nuchal translucency do not show altered intracardiac flow velocities

OBJECTIVE

To study intracardiac flow velocities in first-trimester fetuses with normal nuchal translucency thickness (NT) and those with increased NT.

METHODS

Ultrasound examinations were performed in 85 normal fetuses and 45 fetuses with NT > 95(th) percentile. Follow-up was complete and postmortem examination was performed on terminated pregnancies. Flow velocities during the early (e-wave) and late (a-wave) peaks across the tricuspid and mitral valves were measured and compared, using multilevel analysis, between the fetuses with normal and those with increased NT. In the group with increased NT, fetuses with and without a heart defect irrespective of the karyotype were compared, and in this group, euploid and aneuploid fetuses were compared, irrespective of the presence of a heart defect.

RESULTS

No difference in intracardiac flow velocities was found between fetuses with normal and those with increased NT. Within the group of fetuses with increased NT, there was no difference between the fetuses with and without a cardiac defect. However, comparison of aneuploid with euploid fetuses within the group with increased NT showed that both the e-wave and a-wave peaks were decreased significantly by 3.03 cm/s and 5.95 cm/s, respectively, across the tricuspid valve, and by 3.47 cm/s and 5.92 cm/s, respectively, across the mitral valve (P < 0.05). The most common cardiac malformations were septal defects.

CONCLUSION

There is no difference in intracardiac blood flow velocities between normal fetuses and those with increased NT. This contradicts the theory that NT is caused by impaired atrial contraction or cardiac failure. In fetuses with increased NT, those with aneuploidy show a decreased e-wave and a-wave compared with euploid fetuses. This cannot, however, be explained by the presence of cardiac defects, because there is no difference between fetuses with and without a cardiac defect. Therefore, we hypothesize that the relationship between enlarged NT and cardiac defects can only be explained by a developmental process that coexists at this period of gestation and is linked to cardiovascular development.

Curva de referência para a medida da translucência nucal na população capixaba

OBJETIVO: Estudar o comportamento da medida da translucência nucal (TN) na população capixaba, no período entre a 10ª e a 14ª semanas de gestação. MATERIAIS E MÉTODOS: Estudou-se de forma transversal 853 fetos, consecutivamente, que apresentaram cariótipos ou fenótipos normais. Todos os fetos foram submetidos, durante a ultra-sonografia de rotina, à medida da TN. A análise estatística utilizou o teste "t" de Student e ANOVA. O teste de regressão ajustou o melhor modelo matemático para traduzir o comportamento da TN. RESULTADOS: A idade materna variou de 14 a 49 anos (média de 30,2 anos), sendo que 22,1% encontravam-se com mais de 35 anos. A TN mostrou comportamento crescente com a idade gestacional e o comprimento cabeça-nádegas (CCN). Houve 73 casos (6,46%) de fetos normais com TN maior que 2,5 mm. O melhor modelo matemático encontrado para representar o comportamento da TN foi a regressão linear simples (TN = 0,414 + 0,020 × CCN), que permitiu estabelecer curva de normalidade com os percentis 5, 10, 25, 50, 75, 90 e 95. CONCLUSÃO: A TN apresenta comportamento crescente com o avançar da idade gestacional, no período de 10 a 14 semanas. A população capixaba apresenta medidas de TN semelhantes às demais populações já testadas.

Congenital heart disease and aneuploidy

Congenital heart disease (CHD) is one of the commonest prenatal diagnoses made on routine ultrasound screening. Overall, up to 33% of CHD are associated with fetal aneuploidy. However, some specific cardiac lesions have a significantly greater association with particular chromosomal abnormalities. The majority of fetuses with CHD and aneuploidy also have extra-cardiac anomalies and are best managed by a multidisciplinary team where the management and prognosis of the cardiac defect can be discussed in the context of the baby as a whole. It is therefore important for clinicians involved in the management of fetuses with CHD to be aware of the association of aneuploidy as well as the prognosis and management of these cases, so that they can appropriately counsel the parents. In this chapter, we review the frequency and types of aneuploidy associated with the commonly diagnosed CHD and discuss their management.

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.

Chromosomal distribution of the human cardiovascular transcriptome

On the basis of previous observations in chromosomes 21 and 22, we hypothesize that there is a tissue-specific organization of cardiovascular gene transcripts in the human genome. To examine the distribution of heart-derived transcripts, we assigned a nonredundant set of 4628 fetal and 3574 adult known and uncharacterized cardiovascular expressed-sequence tags (cvESTs) to 5-Mb chromosomal 'windows' on the basis of publicly available sequence mapping data. On a whole-genome level (36,617 genes), chromosome 17 (19.2% in fetal, 16.5% in adult) contained the highest proportion of cvESTs, whereas chromosome Y (2.0% in fetal and adult) contained the lowest. In total, 50 of the 639 windows contained a significantly higher proportion of cvESTs (P < 0.003) compared with the genome-wide cvEST gene density, particularly on gene-dense chromosomes (that is, 17, 19, 22) as opposed to gene-rich chromosomes (for example, 1, 2, 11). This report provides insight into a possible role for complex tissue-specific gene regulation in the human genome.

Ductus venosus flow velocities in relation to the cardiac defects in first-trimester fetuses with enlarged nuchal translucency

OBJECTIVE

Our aim is to study first-trimester ductus venosus (DV) velocities in relation to cardiac abnormalities.

STUDY DESIGN

Ultrasound examination was performed in 85 normal fetuses and 45 fetuses with a nuchal translucency (NT) >95th percentile. Pulsatility index for veins (PIV) and velocity during late diastole (a-V) of the DV were measured and compared with the use of multilevel analysis, between fetuses with a heart defect and those without.

RESULTS

Compared with 85 normal fetuses, the a-V and PIV of the fetuses with NT>95th percentile and normal hearts were decreased and increased, respectively. The a-V and PIV of 11 fetuses with NT>95th percentile and cardiac defects were decreased and increased compared with the 25 fetuses with normal hearts, irrespective of the karyotype. The most common cardiac malformations were septal defects.

CONCLUSION

Fetuses with NT >95th percentile and cardiac defects show markedly changed DV velocities. Because the type of cardiac defects cannot always explain the hemodynamic changes found in these fetuses, some other mechanisms seem to be involved.

How successful is fetal echocardiographic examination in the first trimester of pregnancy?

OBJECTIVE

Transvaginal echocardiography is still rarely incorporated into the first-trimester ultrasound examination, despite the fact that heart defects are the most frequently encountered congenital malformation. This study was undertaken to explore the possibilities of fetal echocardiography in the late first trimester.

METHODS

In 85 women with uncomplicated singleton pregnancies, three transvaginal ultrasound examinations between 11+0 and 13+6 weeks' gestation were performed. The examinations were carried out at weekly intervals and visualization of several echocardiographic planes was attempted (four-chamber view, aortic root, long axis of the aorta, pulmonary trunk with three-vessel view, cross-over of the great arteries). The diameter of the aorta and pulmonary trunk were measured to establish reference ranges.

RESULTS

The success rate of visualization of the different parameters increased with gestational age. The ability to perform a full cardiac examination increased from 20% in week 11 to 92% in week 13. Longitudinally derived growth curves of the aorta and the pulmonary trunk were constructed and both showed a linear increase with gestational age.

CONCLUSIONS

The best time in the first trimester to perform transvaginal echocardiography is at 13+0 to 13+6 weeks' gestation. In this period, a full cardiac examination is possible in 92% of cases. The increase of success rate compared to earlier studies is likely to result from the use of better resolution, high-frequency transvaginal probes. First-trimester echocardiography provides an opportunity to examine the fetal heart early in gestation, especially in patients at risk for cardiac malformations because of a positive family history or in fetuses with increased nuchal translucency.

Cardiac malformations in first-trimester fetuses with increased nuchal translucency: ultrasound diagnosis and postmortem morphology

OBJECTIVE

The aim of this study was to explore the diagnostic accuracy of first-trimester transvaginal echocardiography in fetuses with increased nuchal translucency (NT) thickness, by comparing the ultrasound diagnosis with the findings on postmortem examination or mid-gestational ultrasound and neonatal outcome.

METHODS

Transvaginal echocardiography was performed in 45 fetuses with a NT > 95th centile. Karyotyping was performed in 43. In 20 of the 23 pregnancies in which termination of pregnancy was carried out, postmortem examination was performed to determine the presence and type of heart defect. Mid-gestational echocardiography was performed in ongoing pregnancies and neonatal follow-up information was obtained. Findings on first-trimester transvaginal echocardiography were compared to those of second-trimester echocardiography or the results of postmortem examination. The mean NT in the fetuses with and without heart defects was calculated.

RESULTS

Of the 45 fetuses, heart malformations were suspected on first-trimester ultrasound in 10 (22%), of which eight (80%) were found to have a chromosomal abnormality. Postmortem examination showed minor additional findings in some cases and major discrepancies occurred in none. Septal defects were the most common defects in trisomic fetuses. In three fetuses with a 45 X karyotype, hypoplastic left heart syndrome was diagnosed. Heart defects were diagnosed in three euploid fetuses in which fetal demise occurred. The sensitivity and specificity for the detection of heart defects of transvaginal echocardiography were 88% and 97%, respectively. The mean NT in fetuses with a normal heart (4.3 mm) was significantly smaller than that of fetuses with heart defects (7.4 mm).

CONCLUSION

Transvaginal echocardiography can be performed reliably in first-trimester fetuses with an increased NT. In this study, the proportion of chromosomally abnormal fetuses with a heart defect was not different from that found in newborns, except for cases of Turner syndrome. Fetal demise occurred in all three euploid fetuses with a heart malformation. The fetuses with a heart defect had a larger NT than did those without.

DOPPLERVELOCIMETRIA DO DUTO VENOSO NO CÁLCULO DE RISCO PARA SÍNDROME DE DOWN NO PRIMEIRO TRIMESTRE DA GRAVIDEZ

OBJETIVO: Investigar a validade da Dopplervelocimetria do duto venoso em detectar a síndrome de Down entre 10 e 14 semanas de gestação e propor novo cálculo de risco. PACIENTES E MÉTODOS: Foram estudados 491 fetos, consecutivamente. Em 132 casos realizou-se estudo citogenético no material obtido por biópsia de vilosidade coriônica e em 359 o resultado baseou-se no fenótipo do recém-nascido. Em todos os fetos realizaram-se, além da ultra-sonografia de rotina, a medida da translucência nucal e a Dopplervelocimetria do duto venoso. Na análise estatística foram utilizados o teste paramétrico T de "student", a análise de variância e a regressão linear. Posteriormente, calcularam-se: sensibilidade, especificidade, valores preditivos positivo e negativo, probabilidade de falso-positivo e razões de probabilidades. RESULTADOS: Ocorreram 21 casos de trissomia do cromossomo 21. Desses casos, o fluxo no duto venoso durante a contração atrial foi ausente em três casos e reverso em 17 - sensibilidade de 95,2%. No grupo de fetos normais (470 casos), oito avaliações mostraram alterações do Doppler do duto venoso (especificidade de 98,2%, valores preditivos positivo e negativo de 71,4% e 99,8%, respectivamente, e razões de probabilidades positiva e negativa de 56 e 0,1, respectivamente). CONCLUSÕES: Nossos resultados preliminares sugerem que a presença de síndrome de Down pode ser fortemente suspeitada se houver fluxo reverso ou ausente no duto venoso. Especulamos a possibilidade de cálculo de novo risco para trissomia do 21 com base no Doppler do duto venoso. Utilizando o programa de risco da Fetal Medicine Foundation como risco basal, teríamos um fator multiplicador de aproximadamente 0,1 (razão de probabilidade negativa), caso duto normal, ou de 50 (razão de probabilidade positiva), caso duto reverso ou ausente, e assim, teremos novo risco corrigido.

The role of ductus venosus blood flow assessment in screening for chromosomal abnormalities at 10-16 weeks of gestation

OBJECTIVE

To evaluate the role of ductus venosus blood flow assessment at 10-16 weeks' gestation in screening for chromosomal abnormalities.

METHODS

Ductus venosus blood flow was prospectively evaluated in 1371 consecutive pregnancies between 10 and 16 weeks of gestation. The pulsatility index for veins was calculated. All cases were screened for chromosomal defects combining maternal age and fetal nuchal translucency thickness.

RESULTS

A chromosomal abnormality was found in 20 cases. The overall detection rate, specificity, positive predictive value, negative predictive value and odds ratio for chromosomal abnormalities were 65%, 95.7%, 18.3%, 99.5% and 41 (95% CI 16-108), respectively, when using the 95th centile pulsatility index as a cut-off.

CONCLUSIONS

These preliminary results suggest that evaluation of the ductus venosus pulsatility index at 10-16 weeks' gestation is a useful second-line screening test for chromosomal defects. A combination of nuchal translucency measurement and ductus venosus assessment might increase specificity while maintaining an optimal detection rate for chromosomal abnormalities. Such a policy could identify 55% of all chromosomal abnormalities and about 69% of autosomal trisomies, reducing the need for invasive testing to less than 1%.

Nuchal translucency and its relationship to congenital heart disease

Nuchal translucency refers to the normal subcutaneous space, observed on first trimester ultrasound evaluation, between the skin and cervical spine. Increased nuchal translucency is known to be associated with an increased risk of aneuploidy, particularly Trisomy 21, and recent studies have also identified increased nuchal translucency as a nonspecific marker for various genetic syndromes and multiple structural anomalies, to include congenital heart disease. This increased risk applies to euploid and aneuploid pregnancies and is directly related to the degree of nuchal translucency thickening. This article reviews the role of nuchal translucency as a screening tool for congenital heart disease.

Trisomy 21: 91% detection rate using second-trimester ultrasound markers

OBJECTIVES

To examine cardiovascular and non-cardiovascular prenatal ultrasound markers and determine which markers physicians of varying skill levels could use to identify fetuses with trisomy 21.

METHODS

Eighty second-trimester fetuses with trisomy 21 and 2000 controls underwent real-time plus color Doppler examination of cardiovascular and non-cardiovascular systems followed by amniocentesis. Non-cardiac markers were central nervous system malformations (CNS); choroid plexus cysts (CPC); abnormal nuchal skin fold (NSF); hyperechoic bowel (HB); and pyelectasis (PY). Cardiac markers consisted of ventricular septal defect, right-to-left chamber disproportion (RL); tricuspid regurgitation; mitral regurgitation (MR); pericardial effusion; and outflow tract abnormalities (OFT). Multinomial logistic regression was used to identify interactivity between the markers. Logistic regression was utilized to identify which combinations of markers significantly contributed to the identification of fetuses with trisomy 21 and to compute the likelihood ratio.

RESULTS

All but three markers (CPC, MR, OFT) contributed significantly to the identification of 91% of fetuses with trisomy 21 with a false-positive rate of 14%. When only non-cardiovascular markers were examined, all but CPC contributed to the identification of 60% of fetuses with trisomy 21 with a false-positive rate of 5.9%. Combining right-to-left chamber disproportion with CNS, NSF, HB and PY identified 75% of fetuses with trisomy 21 with a false-positive rate of 6.4%. All markers were independent predictors of trisomy 21 except RL and NSF.

CONCLUSION

Ultrasound can detect between 60 and 91% of fetuses with trisomy 21 depending upon which markers are selected for evaluation.

The association between congenital heart disease and Down syndrome in prenatal life

OBJECTIVE

To assess the relationship between congenital heart disease (CHD) and Down syndrome (DS) in utero.

DESIGN

Retrospective case series.

SUBJECTS

Fifty-two fetuses with a cytogenetic diagnosis of DS managed at our Fetal Cardiology Unit in the study period. In particular, two populations of fetuses with DS were studied: a group of 41 DS fetuses referred to our unit for fetal echocardiography due to the chromosomal anomaly and a second group of 274 fetuses referred because of suspected CHD, 11 of which were found to have DS.

METHODS

All fetuses were submitted to detailed ultrasound evaluation of fetal anatomy. Associated extracardiac anomalies, and presence and type of CHD, were recorded for all fetuses. Karyotyping was obtained by means of cordocentesis or amniocentesis. Necropsy or neonatal echocardiograms were sought for confirmation of the prenatal diagnosis.

RESULTS

In the group of 41 fetuses with known DS, the incidence of CHD was 56% ([atrioventricular septal defect (AVSD) 44%, ventricular septal defect (VSD) 48%], the remainder having other heart defects). Conversely, considering the incidence of DS in fetuses with CHD, 43% of all AVSDs (53% of AVSD with normal visceral situs) were associated with DS, whereas none of the 39 cases of VSD was associated with trisomy 21. Ventricular septal defects were diagnosed only in fetuses referred to our center with a known diagnosis of aneuploidy.

CONCLUSIONS

We have confined that more than half of the fetuses with DS bear a CHD, which is an AVSD in 44% of cases. Conversely, 43% of fetuses with an AVSD have trisomy 21. For VSDS, the situation is controversial, due to the relatively low detection level of this heart defect at the routine mid-trimester obstetric scan.

First-trimester prenatal diagnosis of a thoracic cystic lesion associated with fetal skin edema

An unusual case of chest cyst diagnosed at the end of the first trimester in a dizygotic twin pregnancy and managed conservatively is reported. Between 11 and 14 weeks of gestation, ultrasound revealed a relatively large echopoor lung cyst occupying the left side of the chest, displacing the mediastinum and the heart. This was associated with increased nuchal translucency thickness and generalized skin edema. Subsequent sonograms showed complete resolution of the cyst together with the skin edema. The fetuses were delivered at term and had an uncomplicated postnatal outcome. This case emphasizes the role of reduced venous return as a cause of early fetal hydrops. Diagnosis and follow-up of a congenital lung cyst from the end of the first trimester should enable early intervention to be made.

First trimester screening for structural fetal abnormalities: nuchal translucency sonography

Nuchal translucency refers to the normal subcutaneous space, observed on first trimester ultrasound examination, between the skin and the cervical spine in the fetus. Increased nuchal translucency is known to be associated with an increased risk of aneuploidy, particularly Down syndrome. In addition to this association with aneuploidy, multiple studies have now identified increased nuchal translucency as a nonspecific marker of a wide range of fetal structural abnormalities, to include congenital diaphragmatic hernia, cardiac defects, and various genetic syndromes. The degree of nuchal translucency is directly related to the prevalence of fetal anomalies and may have prognostic significance, especially when found in association with other anomalies. The pathophysiology of increased nuchal translucency is uncertain but may be the result of cardiac failure or alterations in lymphatic drainage. Increased nuchal translucency may identify pregnancies that require further assessment, to include additional sonographic evaluation and possible fetal echocardiography. Further evaluation is required to assess the role of nuchal translucency screening in the general population.

Abnormal ductus venosus blood flow in trisomy 21 fetuses during early pregnancy

OBJECTIVE

Our purpose was to assess the ductus venosus blood flow in trisomy 21 fetuses in the first half of pregnancy and the relation of this blood flow to nuchal thickness.

STUDY DESIGN

The ductus venosus blood flow has been studied in 534 consecutive fetuses between 10 and 18 weeks of gestation who were undergoing prenatal invasive diagnostic procedures. Before the sampling, the velocity during atrial contraction, the pulsatility index for veins, and the ratio of systole-end-systole to diastole were established in the Doppler waveforms and eventually correlated with the fetal karyotype.

RESULTS

Ductus venosus waveforms were successfully obtained in 82% of the pregnancies. Eleven fetuses were found to have trisomy 21; the pulsatility index was abnormally increased (>95th percentile) in 73% (8/11), the ratio of systole-end-systole to diastole was abnormally increased in 45% (5/11), and the velocity during atrial contraction was decreased (<5th percentile) in 27% (3/11).

CONCLUSIONS

An abnormally increased ductus venosus pulsatility index was found in a substantial proportion of early trisomy 21 fetuses, and this was apparently independent of nuchal thickening.

Chromosomally abnormal early ongoing pregnancies: correlation of ultrasound and placental histological findings

The pathophysiology of placental microscopic changes in chromosomally abnormal pregnancies remains poorly understood. We have reviewed the relationship between ultrasound findings and villous histological features in a group of 25 ongoing pregnancies presenting with fetal aneuploidy at 11 to 15 weeks of gestation. The chromosomal abnormalities were diagnosed by chorion villous sampling, and the data were compared with those of a group of 25 chromosomally normal pregnancies undergoing surgical termination and matched for gestational age. The aneuploid group included 10 pregnancies with trisomy 21, nine with trisomy 18, three with triploidy, two with monosomy X, and one with trisomy 13. The overall degree of agreement between the two investigators for the histological diagnosis was good (kappa, 0.64), and the sensitivity of histology ranged between 72.0% and 80.0%. Fetal and placental edema was observed on scan in 10 and 7 cases, respectively, of the aneuploid group and was systematically associated with trophoblastic hypoplasia, stromal edema, or cavitation, reduced vascularization, and ramification of the main villous trunks. Fetoplacental hydrops was not observed in the euploid group. These findings indicate that histological changes observed in the placenta of fetuses from ongoing pregnancies presenting with aneuploidy can be linked with early fetal hydrops. The villous features in these cases are probably secondary to a reduction in the villous circulation due to a cardiovascular defect and leading to generalized stromal edema. The reduced villous branching and trophoblastic hypoplasia could be secondary to the enlargement of all villous types or to a basic defect in placental development.

Reversed end-diastolic umbilical flow in a first-trimester fetus with congenital heart disease

Reversed end-diastolic umbilical artery velocities and a reduced chorionic sac were first seen at 10 weeks in a pregnancy subsequently showing a normal male karyotype on chorionic villi. Four weeks later Doppler studies demonstrated normal umbilical artery waveforms. At 20 weeks, ultrasound examination of the fetus revealed a mild pericardic effusion, hypoplastic righ heart with hypertrophic myocardium and a single umbilical artery, suggesting pulmonary atresia. After neonatal death, pathological studies confirmed pulmonary atresia. This case suggests that reversed end-diastolic umbilical flow in the first trimester may identify a subgroup of fetuses with a lethal abnormality (heart defect, severe intra-uterine retardation, aneuploidy or others).

First trimester ultrasonographic diagnosis of fetal structural abnormalities in a low risk population

OBJECTIVES

Ultrasonographic screening between 12(+0) and 13(+6) weeks for fetal structural abnormalities using transabdominal sonography and, where necessary, transvaginal sonography in a low risk population.

DESIGN

A prospective observational study.

SETTING

London teaching hospital.

METHODS

Pregnant women with a total of 1632 low risk viable fetuses between 12(+0) and 13(+6) weeks of gestation were scanned using transabdominal and, where necessary, transvaginal sonography (40%). If the anatomical survey was normal, the women underwent routine 18-20 week anomaly scans. Pregnancy outcomes were obtained from radiological and neonatal computerised databases, and postal or telephone patient enquiry.

RESULTS

Seventeen (1.0%) major structural abnormalities were diagnosed in the study group. Of these, 11 (64.7%) were diagnosed at the 12-13 week scan, three diagnosed in the mid-trimester and three postnatally. Of the fetal abnormalities diagnosed antenatally, 78.6% were diagnosed in the first trimester. The sensitivity of abnormality detection by the combination of both first and second trimester scans was 82.3%. In addition, a significant number of missed abortions (n = 36) were also diagnosed by the first trimester scan.

CONCLUSION

This study has demonstrated the potential of screening a low risk population for fetal abnormalities at 12-13 weeks of gestation using transabdominal sonography and, where necessary, transvaginal sonography. Larger studies are required to establish the clinical value of the first trimester scan.

Prenatal diagnosis of congenital heart disease

Owing to the widely different levels of experience of examiners, there is a large discrepancy in study results of second trimester ultrasound screening for fetal malformations, which is a result of varying levels of obstetric scanning expertise prevalent at the reporting centre. This holds particularly true for the prenatal diagnosis of congenital heart disease where detection rates ranging from 0 per cent to 60 per cent are being reported. On the other hand, congenital heart disease affects about 4-8 per 1000 live births and is a leading cause of infant mortality, whereas prenatal diagnosis could possibly prevent death and long-term morbidity in some of these neonates. Various screening concepts for more effective detection of congenital heart diseases are analysed in this article, including the more recent technique of early echocardiography between 13 and 15 weeks of gestation. High-risk groups are defined and the group of fetuses with increased thickness of nuchal translucency seems to be of particular interest.

Diagnosis and management of early non-immune hydrops fetalis

Fetal hydrops is a common symptom of fetal disease at any stage of gestation. The aetiological mechanisms leading to non-immune fetal hydrops are complex and their impact variable at different stages of gestation. In early pregnancy, primary or secondary intra-uterine cardiac failures due to major cardiovascular defects are more often linked to a chromosomal abnormality than during the second half of gestation. In these cases, an increase of the nuchal translucency thickness is probably the first stage of fetal hydrops. Depending on the severity of the underlying defect, the next stage is generalized skin oedema with eventual placental oedema, ascites and pleural effusion. The natural history of fetal hydrops remains poorly understood and thus the prognostic factors determining fetal outcome are still unknown. Examination of the fetal nuchal anatomy between 10 and 15 weeks of gestation and the follow-up of these pregnancies offer an opportunity for an early screening in most aneuploidies and cardiovascular defects, and a better understanding of the aetiopathology of fetal hydrops.

Abnormalities of the heart and great arteries in first trimester chromosomally abnormal fetuses

Pathological examination of the heart and great arteries was performed in 112 chromosomally abnormal fetuses after surgical termination of pregnancy at 11-16 weeks of gestation. The chromosomal abnormalities were diagnosed by chorion villus sampling which was carried out because screening of the pregnancies by a combination of maternal age and fetal nuchal translucency thickness at 10-14 weeks of gestation identified them as being at increased risk. The group consisted of 60 fetuses with trisomy 21, 29 with trisomy 18, 17 with trisomy 13 and 6 with Ullrich-Turner syndrome. The most common cardiac lesion seen in trisomy 21 fetuses was an atrioventricular or ventricular septal defect. Trisomy 18 was associated with ventricular septal defects and/or polyvalvular abnormalities. In trisomy 13, there were atrioventricular or ventricular septal defects, valvular abnormalities, and either narrowing of the isthmus or truncus arteriosus. Ullrich-Turner syndrome was associated with severe narrowing of the whole aortic arch. In all four groups of chromosomally abnormal fetuses, the aortic isthmus was significantly narrower than in normal fetuses and the degree of narrowing was significantly greater in fetuses with high nuchal translucency thickness. It is postulated that narrowing of the aortic isthmus may be the basis of increased nuchal translucency thickness in all four chromosomal abnormalities.

Noninvasive first-trimester screening for fetal aneuploidy

We reviewed all studies concerning noninvasive first trimester screening for fetal aneuploidy obtained from a MEDLINE search through June 1996 with additional sources identified through cross-referencing. Three screening and diagnostic modalities are of potential application in noninvasive first trimester testing for fetal aneuploidy: ultrasound, maternal biochemical markers, and analysis of fetal cells retrieved from maternal sources. Sensitivities of the sonographic finding of nuchal translucency thickness in combination with maternal age for trisomy 21, performed between 10 and 14 weeks of gestation in experienced hands, and maternal biochemical markers independently may be as high as 86 percent and 60 percent, respectively. Sensitivity, specificity, and predictive values of these diagnostic modalities alone, in combination with each other, or in conjunction with other predisposing factors such as maternal age, in large low risk populations have not currently been established. Analysis of fetal cells retrieved from maternal sources, although more complex, may offer definitive noninvasive prenatal diagnosis yet is not currently available in clinical practice. We conclude that noninvasive first trimester screening for fetal aneuploidy modalities including sonographic examination for nuchal translucency thickness and maternal biochemical markers, is feasible. Clinical feasibility; and all-encompassing clinical management paradigms of these and other early noninvasive first trimester screening methods for fetal aneuploidy, are not yet available.