Increased nuchal translucency in trisomy 21 fetuses: relationship to narrowing of the aortic isthmus

Nuchal Translucency and Congenital Heart Defects

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

[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 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.

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.

Cardiac function in trisomy 21 fetuses

OBJECTIVES

Trisomy 21 is associated with an increased nuchal translucency thickness (NT), abnormal ductus venosus (DV) flow at 11-14 weeks' gestation and congenital heart defects (CHD), and cardiac dysfunction has been hypothesized as the link between them. We therefore aimed to investigate whether cardiac function is altered in trisomy 21 fetuses.

METHODS

Between December 2003 and June 2009, we performed echocardiography on 46 trisomy 21 fetuses (28 with structurally normal heart and 18 with CHD) and on 191 chromosomally/phenotypically normal fetuses with a confirmed normal heart (87 with normal NT and 104 with NT ≥ 95(th) percentile), between 11 and 35 weeks' gestation. Measurements included: E- and A-wave peak velocity, E/A velocity ratio and E/time velocity integral (TVI) ratio over atrioventricular valves; myocardial performance index (MPI); semilunar valve peak velocity and acceleration time; stroke volume (SV); cardiac output; and DV pulsatility index for veins (PIV) at 11-14 weeks' gestation. Data were categorized into three different age groups for analysis (11 to 13 + 6, 14 to 21 + 6 and 22 to 35 weeks' gestation).

RESULTS

The tricuspid valve (TV) A-wave velocity and aortic valve peak velocity were significantly reduced in trisomy 21 compared with normal fetuses. Other highly significant differences found in trisomy 21 fetuses at 11-14 weeks' were increased TV-E/A ratio and DV-PIV, and decreased pulmonary valve peak velocity. We also observed evidence of left ventricular (LV) systolic dysfunction, reduced SV and increased MPI. After 14 weeks' gestation, the mitral valve A-wave peak velocity and E/TVI ratio were significantly reduced in the trisomy 21 fetuses with normal hearts compared with the controls with increased NT.

CONCLUSIONS

In comparison with controls with normal or increased NT, cardiac function in trisomy 21 fetuses is abnormal irrespective of the presence of CHD. Evidence for cardiac loading (increased preload and afterload) and LV systolic (in the first trimester) and later diastolic dysfunction was observed.

Fetal cardiac function between 11 and 35 weeks' gestation and nuchal translucency thickness

OBJECTIVES

The pathophysiological background of an increased nuchal translucency (NT) is still poorly understood. Cardiac dysfunction has been proposed as a cause. The aim of this study was to determine if, in fetuses with normal hearts, the NT thickness is related to cardiac function throughout gestation.

METHODS

The NT was measured in 191 karyotypically/phenotypically normal fetuses with structurally normal hearts and was increased (≥ 95(th) centile) in 104. All fetuses had been referred for fetal echocardiography and were prospectively included between October 1 2003 and April 1 2009. Three-hundred and ten echocardiograms were performed between 11 and 35 weeks' gestation. The E- and A-wave velocity, E/A velocity ratio, E/time velocity integral (TVI) ratio over the atrioventricular (AV) valves, myocardial performance index, acceleration time (AT) and peak velocity over the semilunar valves, stroke volume (SV) and cardiac output (CO) as well as the ductus venosus pulsatility index for veins at 11-14 weeks' gestation (DV-PIV), were measured. A multilevel analysis was performed using the NT multiples of the median (MoM) as a continuous variable.

RESULTS

AV-E- and A-wave velocities, E/A velocity ratios, semilunar valve peak velocity, SV, CO and aortic valve (AoV) AT increased significantly with advancing gestation. At 11-14 weeks' gestation, the AoV-AT, tricuspid valve (TV)-E/A, TV-E/TVI ratios and DV-PIV increased, and the pulmonary valve (PV) AT decreased, with increasing NT-MoMs. After midgestation, the PV-AT increased and the AoV-AT, TV-E/A and TV-E/TVI ratios decreased with increasing NT-MoMs.

CONCLUSIONS

NT thickness is related to right ventricular diastolic function and semilunar valve AT. Our findings suggest improved first-trimester, but later reduced, right ventricular relaxation and discordant ventricular afterload in fetuses with an increased NT.

The nuchal translucency and the fetal heart: a literature review

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

Ehlers-Danlos type IV syndrome in a patient with Down syndrome: simple co-occurrence or true association?

Down syndrome, a common chromosome aneuploidy, has been associated with an increased incidence of cutaneous disorders. The simultaneous occurrence with Ehlers-Danlos syndrome (EDS) is rare. We report here the clinical case of a 19-year-old female patient with Down syndrome (trisomy 21) who was also affected by EDS type IV. She died from spontaneous bleeding due to rupture of nonaneurysmal abdominal aorta. Since the affected chromosomes in these two syndromes are different (21 and 2, respectively), the concomitant appearance of Down syndrome and EDS type IV in our patient, though clinically intriguing, most likely represents a co-occurrence. However, the possibility that a presently unknown link may exist between these syndromes cannot be ruled out.

Nuchal Translucency Thickness in Fetuses With Chromosomal Translocation at 11–12 Weeks of Gestation

OBJECTIVE

To investigate differences in nuchal translucency thickness among fetuses in which either parent is a balanced chromosome translocation carrier.

METHODS

A prospective observational study was conducted with 98 pregnant women in the first trimester. Each had been advised to undergo chorionic villous sampling for fetal karyotyping for the indication of parental balanced chromosomal translocation. Fetal nuchal translucency measurement was performed before chorionic villous sampling. Nuchal translucency thickness was compared among fetuses with 3 kinds of karyotypes: normal, balanced translocation, and unbalanced translocation.

RESULTS

There were no differences in maternal age, gestational age, parity, and number of previous miscarriages among pregnancies with normal karyotype, balanced chromosomal translocation, and unbalanced chromosomal translocation. A significantly greater nuchal translucency thickness was shown in the unbalanced chromosomal translocation group (2.9 +/- 1.2 mm) compared with both the balanced chromosomal translocation group (1.0 +/- 0.6 mm; P < .001) and the normal karyotype group (1.0 +/- 0.8 mm; P < .001). No statistically significant difference in nuchal translucency thickness was found between the balanced chromosomal translocation group and normal karyotype group (P = .991). Nuchal translucency thickness did not differ significantly between unbalanced chromosomal translocation dependent on paternal origin and that dependent on maternal origin (P = .611).

CONCLUSION

In fetuses with unbalanced chromosomal translocation, nuchal translucency thickness tends to be greater, and thus nuchal translucency measurement might be considered part of the investigation for pregnancies marked by a parental balanced chromosomal translocation.

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.

Physiopathologie de la nuque épaisse

OBJECTIVES

Increased physiological nuchal translucency (NT) between 10 and 14 weeks of gestation is associated with chromosomal anomalies, mainly trisomy 21, developmental malformations and with normal fetus outcome. The aim of this study is to understand the cellular mechanisms leading to increased NT.

MATERIALS AND METHODS

We examined five nuchal samples, a normal fetus from a fetal loss with a normal NT, a trisomy 21 fetus with an increased NT, two karyotypically normal fetuses with increased NT and a fetus with increased NT associated with an isolated cardiopathy. These morphological data were correlated with data from the literature.

RESULTS

The pathological mechanism of increased NT is a posterior median mesenchymal edema of the fetal neck. It is associated with bilateral distension of jugular lymphatic vessels.

CONCLUSION

Increased NT mechanisms are mainly related to a disturbance of embryonic lymphangiogenesis which might be a common denominator of the alteration of the composition of the extracellular matrix and of the cardiovascular and hemodynamic disorder. Nuchal morphological studies should be systematically performed to understand the mechanisms of increased NT.

Abnormal lymphatic development in trisomy 16 mouse embryos precedes nuchal edema

Ultrasound measurement of increased nuchal translucency is a method of risk assessment for heart malformations and trisomy 21 in human pregnancy. The developmental background of this nuchal edema is still not sufficiently understood. We have studied the process in trisomy 16 mice that show nuchal edema and heart malformations. We used trisomy 16 and wild-type (WT) embryos from embryonic day (E) 12.5 to E18.5. In WT embryos at E13, bilateral jugular lymphatic sacs are visible that share a lymphatic-venous membrane with the jugular vein. We could not in any case discern a valve between these vessels. At E14 in the TS16 embryos, the lymphatic sacs become enlarged showing abnormally thickened endothelium, specifically at the site of the membrane. In these embryos, severe edema develops in the nuchal region. There is a very close colocalisation of the nerves with the vascular structures. The start of reorganization of the jugular lymphatic sac to a lymph node is observed in both wild-type and TS16 but is diminished in the latter. In conclusion, abnormal size and structure of the jugular lymphatic sacs coincides with the development of nuchal edema. A disturbance of lymphangiogenesis might be the basis for increased nuchal translucency that is often observed in diseased human fetuses.

First- and midtrimester Down syndrome screening and detection

Overall, Down syndrome detection capabilities have improved remarkably over the last 2 decades. Widely practiced first-trimester screening and less extensively elevated midtrimester urine screening promise even greater accuracy than was available a decade ago. Recently, the combination of first- and second-trimester screening has been reported to enhance discrimination of the Down syndrome fetus from normal cases. Although the advances are welcome, they present the significant prospect of multiple competitive algorithms with the risk of confusing patients, practitioners, and health care planners. The need for reasonable consensus has never been more pressing.

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.

Clinical impact of first and early second trimester fetal echocardiography on high risk pregnancies

OBJECTIVE

To evaluate the clinical impact of fetal echocardiography before 16 weeks' gestation on the management of pregnancies with fetuses at risk of congenital heart disease.

DESIGN AND SETTING

Observational study in a fetal medicine unit.

PARTICIPANTS AND METHODS

222 consecutive women with high risk pregnancies (230 fetuses) underwent transabdominal fetal echocardiography at a median gestation of 14(+1) weeks. For 10%, transvaginal scans were also performed. Criteria for normal scans were normal sequential segmental analysis, symmetrical four chamber view, normal semilunar valves, arterial outflow tracts, and ductal and aortic arches. Early scans were compared with mid-second trimester fetal echocardiography. Postmortem and postnatal data were added. Adverse pregnancy outcomes were diagnosis of a major cardiac or extracardiac abnormality, chromosomal defects, intrauterine death, or termination of pregnancy.

RESULTS

There were 21 abnormal cardiac scans (9%): 14 major structural defects (eight isolated, six with chromosomal or extracardiac abnormalities) in pregnancies resulting in three live births, one intrauterine death, and 10 terminated pregnancies. Seven scans showed asymmetry between right and left sided structures (two isolated, five with chromosomal or extracardiac abnormalities); six of the seven pregnancies were terminated. The scans were normal in 199 cases (87%). Cardiac follow up of 184 of 199 babies (93%) confirmed situs and connections. One case each of pulmonary stenosis and ventricular septal defect requiring postnatal intervention were diagnosed at later scans. In 28 of 199 (14%) babies there was a non-cardiac adverse outcome. First examination was not diagnostic for 10 (4%).

CONCLUSION

Early fetal echocardiography in high risk pregnancies was diagnostic in 96%. Abnormal cardiac scans (isolated in 48%, major structural defects in 67%) led to termination of pregnancy in 76%. Most cardiac scans were normal, allowing family reassurance. The high number of adverse outcomes with normal cardiac anatomy stresses the need for a multidisciplinary approach to early fetal echocardiography.

Disappearance of enlarged nuchal translucency before 14 weeks' gestation: relationship with chromosomal abnormalities and pregnancy outcome

OBJECTIVE

The aim of this study was to investigate the natural course of enlarged nuchal translucency (NT) and to determine if its disappearance before 14 weeks' gestation is a favorable prognostic sign in relation to fetal karyotype and pregnancy outcome.

METHODS

A total of 147 women with increased NT (> 95th centile) at first measurement were included in this study. A second measurement was performed in all cases, at an interval of at least 2 days. Both measurements were taken between 10 + 3 and 14 + 0 weeks. All women underwent chorionic villus sampling or amniocentesis for subsequent karyotyping. In those women with a normal karyotype, a fetal anomaly scan was performed at 20 weeks' gestation. Pregnancy outcome was recorded in all cases. The finding of persistent or disappearing NT enlargement was analyzed in relation to fetal karyotype and pregnancy outcome.

RESULTS

Of the 147 paired measurements, NT remained enlarged at the second measurement in 121 (82%) cases. An abnormal karyotype was found in 35% of these cases. In 26 (18%) fetuses the NT measurement was found to be below the 95th percentile at the second measurement and in only two of them an abnormal karyotype was found (8%). In the 103 chromosomally normal fetuses an adverse outcome (i.e. fetal loss or structural defects) was recorded in 22 fetuses with persistent enlargement (28%) and in four fetuses with disappearing enlargement (17%).

CONCLUSIONS

Disappearance of an enlarged NT before 14 weeks' gestation is not a rare phenomenon and seems to be a favorable prognostic sign with respect to fetal karyotype. Overall, no significant difference in pregnancy outcome was found between chromosomally normal fetuses with persisting or disappearing NT enlargement.

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.

Structural and functional cardiac abnormalities identified prior to 16 weeks' gestation in fetuses with increased nuchal translucency

OBJECTIVE

To determine the accuracy and practicality of fetal echocardiography in the identification of structural and functional cardiac abnormalities prior to 16 weeks' gestation in fetuses with increased nuchal translucency thickness (NT).

METHODS

Between January 1996 and June 2002 early fetal echocardiography using the transvaginal route was performed at 12-16 weeks' gestation on 275 fetuses with increased NT. The abnormal cardiac findings were classified as either structural (congenital heart defects) or functional, defined as transient phenomena which might later disappear, such as isolated tricuspid regurgitation and an enlarged ascending aorta. The abnormal findings were related to pregnancy outcome, including autopsy results, karyotyping results, and late fetal and neonatal echocardiography.

RESULTS

Cardiac abnormalities were present in 61 fetuses overall (22.2%); including structural cardiac defects in 37 fetuses (13.5%) and functional abnormalities in 24 fetuses (8.7%). Structural cardiac abnormalities were associated with abnormal karyotype in 24 fetuses and normal karyotype in 13 fetuses. Of the 24 fetuses with functional cardiac abnormalities, 2 (8.3%) had isolated tricuspid regurgitation and 22 (91.7%) had enlarged ascending aorta. Abnormal karyotype was present in this group in 4 cases (16.7%).

CONCLUSION

Increased NT can be used to define a high-risk group that should receive specialized early fetal echocardiography. This is a reliable technique with great potential for the diagnosis of both structural and functional cardiac abnormalities.

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.

Blackfan-Diamond anemia and dyserythropoietic anemia presenting with increased nuchal translucency at 12 weeks of gestation

Blackfan-Diamond anemia is a congenital hypoplastic anemia with a birth prevalence of about 1 in 200,000, usually presenting in the first few months of life and commonly associated with cardiac, urogenital and digital anomalies. Congenital dyserythropoietic anemias are a group of rare congenital anemias characterized by ineffective erythropoiesis. We report on two cases of congenital fetal anemia, one with Blackfan-Diamond anemia and one with dyserythropoietic anemia, presenting with increased nuchal translucency at 12 weeks of gestation.

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.

Incidence of major structural cardiac defects associated with increased nuchal translucency but normal karyotype

OBJECTIVE

To examine the association between increased nuchal translucency thickness and major cardiac defects in chromosomally normal fetuses.

SETTING

Tertiary referral unit for fetal medicine and fetal cardiology.

METHODS

During a 4-year period (January 1997 to January 2001), detailed echocardiography was performed in 1319 chromosomally normal fetuses with increased nuchal translucency thickness at 10-14 weeks of gestation. The incidence of major cardiac defects was examined in relation to the fetal NT at the 10-14-week scan.

RESULTS

Major cardiac defects were diagnosed in 60 (4.5%) of the 1319 fetuses. In fetuses with a nuchal translucency thickness in the range of 2.5-3.4 mm, the incidence of major cardiac defects was 2.5% (18/722; 95% confidence interval, 1.5-3.9) and in those with a nuchal translucency thickness > or =3.5 mm, it was 7% (42/597; 95% confidence interval, 5.1-9.4).

CONCLUSION

Specialist echocardiography is indicated in all fetuses with increased nuchal translucency thickness because, in such fetuses, the incidence of major cardiac defects is substantially higher than in pregnancies with maternal diabetes, family history and exposure to drugs, where fetal echocardiography is widely considered to be necessary.

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.

Fetal aortic arch measurements between 14 and 38 weeks' gestation: in-utero ultrasonographic study

OBJECTIVE

To establish in-utero reference ranges for fetal transverse aortic arch diameter (TAD) and distal aortic isthmus diameter (DAID) using high-resolution ultrasound techniques.

DESIGN

A prospective, cross-sectional study was performed on 125 normal singleton pregnancies between 14 and 38 weeks' gestation. Transverse and diameter and DAID were measured by transvaginal ultrasonography until 17 weeks' gestation, and by abdominal ultrasound between 18 and 38 weeks' gestation.

RESULTS

Transverse arch diameter as a function of gestational age was expressed by the regression equation TAD = -1.17 + 0.169 X GA, and DAID = -1.39 + 0.189 X GA; TAD and DAID are transverse aortic and distal aortic isthmus diameters expressed in millimeters and GA is gestational age in weeks. The correlation r = 0.924 and 0.938 was found to be highly statistically significant (P < 0.001) for TAD and DAID. The normal mean of TAD and DAID per week and the 95% prediction limits were also defined.

CONCLUSIONS

The normative data established by us may be helpful in the prenatal diagnosis of congenital heart defects, including abnormal growth of the aortic arch.

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.

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).

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.