Increased nuchal translucency at 10-14 weeks of gestation as a marker for major cardiac defects

Screening for aneuploidy in the first trimester by assessment of blood flow in the ductus venosus

OBJECTIVE

To assess the role of ductus venosus Doppler assessment in screening for fetal aneuploidy in pregnancies at 11-14 weeks of gestation.

DESIGN

Prospective observational study.

SETTING

A tertiary referral fetal medicine unit.

POPULATION

Two hundred fifty-six consecutive pregnancies between 11 and 14 weeks of gestation referred to our unit.

METHODS

Nuchal translucency was measured and colour Doppler imaging was used to assess normal (forward) or abnormal (absence/reversed) ductus venosus flow during atrial contraction.

MAIN OUTCOME MEASURES

Fetal karyotype, structural abnormalities and pregnancy outcomes.

RESULTS

The nuchal translucency measurement was > or = 95th centile in 90 (35.2%) pregnancies, and 123 (48.0%) had a nuchal translucency-related risk of > or = 1:300. There were 46 chromosomally abnormal pregnancies and six euploid pregnancies with adverse outcome. The prevalence of abnormal ductus venosus Doppler waveforms in normal pregnancies was 4.49% (95% CI 1.76-8.76%). The sensitivities of abnormal nuchal translucency measurement alone, ductus venosus velocimetry alone or nuchal translucency and ductus venosus combined for Down's Syndrome were 80.4%, 58.7% and 93.5%, respectively. The likelihood ratios for aneuploidy with abnormal nuchal translucency measurement alone, ductus venosus velocimetry alone or nuchal translucency and ductus venosus combined were 3.33, 9.83 and 3.48, respectively.

CONCLUSION

There is clear association between abnormal flow in the ductus venosus and fetal aneuploidy. The use of ductus venosus velocimetry in combination with nuchal translucency is better than either test alone, since it increases the sensitivity in the detection of Down's Syndrome to 94% and decreases the likelihood ratio of a negative test to 0.08.

Application of ductus venosus Doppler velocimetry for the detection of fetal aneuploidy in the first trimester of pregnancy

OBJECTIVE

To test the hypothesis the application of ductus venosus Doppler velocimetry may serve as a screening tool between 10 and 14 weeks' gestation for the detection of fetuses with chromosomal abnormalities.

METHODS

372 consecutive fetuses were studied. Based on prior study, a chromosomal abnormality was suspected when either the nuchal translucency was above the 95th centile, or there was reversed or absent flow in the ductus venosus during atrial contraction. Sensitivity, specificity, and the negative and positive predictive values were calculated.

RESULTS

There were 29 chromosomally abnormal fetuses. Of these 29 fetuses, ductus venosus blood flow during atrial contraction was either absent (n = 2) or reversed (n = 25) in 93.1%. In the chromosomally normal fetuses (n = 343), only 6 (1.7%) had abnormal Doppler profiles in the ductus venosus (specificity = 98.3%, positive and negative predictive values = 81.8% and 99.4%, respectively).

CONCLUSION

The Doppler waveform of the ductus venosus was at least equal to NT thickness measurement for the detection of chromosomal abnormalities.

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.

Early prenatal diagnosis of major cardiac anomalies in a high-risk population

OBJECTIVE

To examine the accuracy of early fetal echocardiography performed in a high-risk population combining transvaginal and transabdominal routes.

METHODS

A series of 330 high-risk pregnancies were screened by transvaginal and transabdominal scan at 12-17 weeks' gestation in a prospective multicentre trial in Spain between September 1999 and May 2001. A total of 334 fetal heart examinations were performed, including four twin pregnancies. Maternal age ranged from 17 to 46 years (mean 33 years with 36% of women over 34 years). The median gestational age at scan was 14.2 weeks (range 12-17 weeks). For each fetus, visualization of the four-chamber view, the origin of the great arteries, aortic and ductal arches and systemic venous return was attempted in a segmental approach. B-mode and colour/pulsed Doppler flow imaging were used in all cases. The duration of complete heart examination was less than 30 minutes. The examinations were performed by three experienced operators. Reliability was assessed by conventional transabdominal echocardiography at 20-22 weeks, by postnatal follow-up in the first three months of life, and/or by autopsy in cases of termination of pregnancy.

RESULTS

The rate of successful visualization of the fetal heart was 94.6% (316/334). In 48 out of 334 (14.4%) fetuses the final diagnosis was abnormal. In 38 out of 48 (79.2%) cases with heart defects the diagnosis was suspected at early echocardiography. In the group with congenital heart defects, 27 cases had an abnormal karyotype (56.3%) and 31 cases showed extracardiac anomalies (64.6%). There were 10 false-negative cases at early scan. There were no false-positive diagnoses.

CONCLUSIONS

This experience stresses the usefulness of early fetal echocardiography when performed by expert operators on fetuses specifically at risk for cardiac disease. The high rate of successful visualization of the fetal heart provides a reliable diagnosis of major cardiac defects at this early stage of pregnancy.

Early fetal anomaly scanning in a population at increased risk of abnormalities

OBJECTIVES

To determine the effectiveness of early fetal anomaly scanning in a population at risk of fetal anomalies.

DESIGN

A prospective study in a tertiary center of 101 consecutive fetuses at risk of congenital anomalies at 11-14 weeks of gestation.

RESULTS

The principal (93/101 = 92%) reason for referral was having a previously affected infant. Nine (9/101 = 9%) fetuses were shown to have structural anomalies at the 11-14-week scan. In five of nine structurally affected fetuses, the nature of the anomalies was similar to that established in a previously affected pregnancy, four of which had a recurrence of an autosomal recessive syndrome. In two fetuses with a normal 11-14-week scan, anomalies were detected at the 18-21-week (arthrogryposis) or 30-week (cardiomyopathy) scans.

CONCLUSIONS

The majority of fetal anomalies can be diagnosed in the late first/early second trimesters of pregnancy. This will be of particular advantage to those women who are at high risk of having affected offspring. However, as fetal anomalies may present at varying gestational ages, the standard 18-21-week scan cannot be abandoned. The effectiveness of the early pregnancy scan depends on the natural history of anomalies (gestational age at onset) and the variable phenotypic expression of anomalies/syndromes.

Prenatal diagnosis of 22q11 microdeletion in an early second-trimester fetus with conotruncal anomaly presenting with increased nuchal translucency and bilateral intracardiac echogenic foci

We report on a 16-week fetus, in which detection of increased nuchal translucency thickness and bilateral intracardiac echogenic foci led to the prenatal diagnosis of truncus arteriosus communis, interruption of the aortic arch and aplastic thymus. Cytogenetic examination confirmed a 22q11.2 microdeletion consistent with the suspected CATCH 22 syndrome. Subsequently hydrops fetalis developed and the fetus died in utero at 18 weeks. This case report supports the hypothesis that both cardiac failure and left ventricular outflow tract obstruction may cause increased nuchal translucency thickness. The association between increased nuchal translucency thickness and CATCH 22 syndrome should be considered in diagnostic procedures. The sonographic diagnosis of both increased nuchal translucency thickness and intracardiac echogenic foci requires specialist ultrasonography and echocardiography. In particular, identification of right-sided or bilateral echogenic foci should prompt further detailed examination.

Increased fetal nuchal translucency at 11-14 weeks

Nuchal translucency (NT) is the sonographic appearance of a subcutaneous collection of fluid behind the fetal neck. The measurement of fetal NT thickness at the 11-14-week scan has been combined with maternal age to provide an effective method of screening for trisomy 21; for an invasive testing rate of 5%, about 75% of trisomic pregnancies can be identified. When maternal serum free-beta human chorionic gonadotrophin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11-14 weeks are also taken into account, the detection rate of chromosomal defects is about 90%. Increased NT can also identify a high proportion of other chromosomal abnormalities and is associated with major defects of the heart and great arteries, and a wide range of skeletal dysplasias and genetic syndromes. In monochorionic twins, discordancy for increased NT is an early marker of twin-to-twin transfusion syndrome (TTTS). As with the introduction of any new technology into routine clinical practice, it is essential that those undertaking the 11-14-week scan are adequately trained and their results are subjected to rigorous audit.

Ultrasound diagnosis of structural abnormalities in the first trimester

The advances in ultrasound technology have made it possible to identify fetal structural abnormalities and genetic syndromes in the first trimester. First trimester prenatal diagnosis of fetal central nervous system, renal, gastrointestinal, cardiac, and skeletal abnormalities is reviewed.

Increased nuchal translucency and congenital heart defects in euploid fetuses. The Szeged experience

OBJECTIVE

To determine the utility of the first-trimester fetal nuchal translucency (NT) thickness in the prediction of fetal cardiac malformations.

DESIGN

Retrospective study.

SETTING

Department of Obstetrics and Gynecology and Medical Genetics, University of Szeged.

METHODS

The pre- and postnatal course and outcome, and the relationship between the first-trimester fetal NT thickness and fetal congenital heart defects (CHDs) in 4309 pregnancies ended up with birth or therapeutic abortion between January 1998 and June 2000 were registered. Prenatal care included first- and second-trimester fetal sonography at weeks 10-13 and 18-20, respectively.

RESULTS

4251 births and 58 first- and second-trimester therapeutic abortions due to lethal congenital malformations or chromosomal abnormalities were recorded. Altogether 209 (4.9%) congenital malformations were detected, 39 (18.7%) of which were heart defects with normal karyotype. At birth, 151 congenital malformations were diagnosed, 34 of them were known prenatally. The prevalence of CHDs was 9 per 1000 pregnancies. The measurement of fetal NT thickness was available in 35 of the 39 fetuses with heart defects: it was > or = 3 mm in 18 (51.4%) and <3 mm in 17 (48.6%). A sensitivity of 51.4% was found at a cutoff of 3mm.

CONCLUSIONS

An increased NT thickness in chromosomally normal fetuses was found to be highly associated with CHDs and identified in more than half of the affected cases. Furthermore, an increased NT of > or = 3 mm can be regarded a selection criterion for early second-trimester targeted fetal echocardiography and for increased fetal and neonatal surveillance.

Routine ultrasound screening in diabetic pregnancies

OBJECTIVES

To assess the detection rate of congenital fetal malformations and specific problems related to routine ultrasound screening in women with pre-existing diabetes.

METHODS

A retrospective study was carried out to assess the performance of routine ultrasound screening in women with pre-existing diabetes (Types 1 and 2) within a tertiary institution. The incidence, type and risk factors for congenital fetal malformations were determined. The detection rate of fetal anomalies for diabetic women was compared with that for the low-risk population. Factors affecting these detection rates were evaluated.

RESULTS

During the study period, 12 169 low-risk pregnant women and 130 women with pre-existing diabetes had routine ultrasound screening performed within the institution. A total of 10 major anomalies (7.7%) and three minor anomalies (2.3%) were present in the fetuses of the diabetic women. Central nervous system and cardiovascular system anomalies accounted for 60% of the major anomalies. Periconceptional hemoglobin A1c of more than 9% was associated with a high prevalence of major anomalies (143/1000). Women who had fetuses with major anomalies had a significantly higher incidence of obesity (78% vs. 37%; P < 0.05). Ultrasound examination of these diabetic pregnancies showed high incidences of suboptimal image quality (37%), incomplete examinations, and repeat examinations (17%). Compared to the 'low-risk' non-diabetic population from the same institution, the relative risk for a major congenital anomaly among the diabetic women was 5.9-fold higher (95% confidence interval, 2.9-11.9). The detection rate for major fetal anomalies was significantly lower for diabetic women (30% vs. 73%; P < 0.01), and the mean body mass index for the diabetic group was significantly higher (29 vs. 23 kg/m2; P < 0.001).

CONCLUSION

The incidence of congenital anomalies is higher in diabetic pregnancies. Unfortunately, the detection rate for fetal anomalies by antenatal ultrasound scan was significantly worse than that for the low-risk population. This is likely to be related to the maternal body habitus and unsatisfactory examinations. Methods to overcome these difficulties are discussed.

Poor prenatal detection rate of cardiac anomalies in Noonan syndrome

BACKGROUND

The wide variation and nonspecific nature of many of the associated ultrasonographic findings complicate prenatal diagnosis of Noonan syndrome. The aim of the present study was to define the rate of prenatal diagnosis of heart malformations in cases diagnosed postnatally with Noonan syndrome.

METHODS

English-language literature review of 29 cases of Noonan syndrome examined prenatally with confirmed postnatal diagnosis and four case reports from our center.

RESULTS

Cases were evaluated for cervical spine pathologies, cardiac anomalies and other pathological findings, including hydrops fetalis and polyhydramnios. Cardiac anomalies were suspected in only nine of 33 cases; three of these were associated with cystic hygroma. Cardiac anomalies were eventually diagnosed in 31/33 cases postnatally. Polyhydramnios was diagnosed in 19/33 cases in the third trimester, and hydrops fetalis was detected in eight of 33. Cystic hygroma was present in a total of nine cases at mid-trimester.

CONCLUSIONS

Noonan syndrome is characterized by late-onset and progressive pathologies, particularly the associated cardiac anomalies, which develop through the course of gestation and postnatal life. This complicates or precludes prenatal diagnosis at mid-trimester or at any time in the prenatal period, and partly explains the low rate of detection of fetal cardiac lesions in this syndrome.

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.

Significance of chromosome 22q11 analysis after detection of an increased first-trimester nuchal translucency

OBJECTIVE

To determine the value of performing routine fluorescent in situ hybridization (FISH) for microdeletions of chromosome 22q11 when karyotyping fetuses with increased nuchal translucency.

DESIGN

This was a prospective observational study carried out over an 18-month period. Fetal karyotyping by chorionic villus sampling was offered to 5429 women attending for a routine booking scan in the first trimester when their nuchal translucency adjusted risk for Down syndrome was > or = 1 in 300. Cytogenetic samples were routinely tested for the 22q11 microdeletion when the nuchal translucency was > or = 3 mm.

RESULTS

The prevalence of increased nuchal translucency > or = 2.5 mm was 180 (3.3%) and > or = 3.5 mm was 42 (0.8%). None of 75 fetuses with an increased nuchal translucency and normal karyotype demonstrated a 22q11 microdeletion on FISH analysis. In the same cohort, 3 of 20 (15%) cases of major congenital heart defects in which nuchal translucency was measured, had a nuchal translucency measurement > or = 2.5 mm.

CONCLUSIONS

Routine FISH analysis for chromosome 22q11 microdeletions at the time of chorionic villus sampling for increased first-trimester nuchal translucency is of limited value. As a significant proportion of fetuses with increased nuchal translucency will be found to have congenital heart defects later in the pregnancy, FISH analysis for chromosome 22q11 microdeletions can be targeted to fetuses with specific congenital heart defects. Tissue from the chorionic villus sampling should therefore be stored for subsequent analysis, until after detailed echocardiography is performed.

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%.

Early prenatal diagnosis of major congenital heart defects

Specialized fetal echocardiography at 18 to 22 weeks for high-risk groups is well established as being sensitive and specific for most cardiac abnormalities. Early fetal echocardiography (< 16(+0) weeks, i.e. 16 weeks and 0 days) is a feasible alternative to mid second trimester scanning for families at risk of congenital heart disease. Two main areas have contributed to the increasing interest in first and early second trimester fetal echo. The recognition of the association between increased nuchal translucency and structural heart abnormalities has led to the identification of an important high-risk group at 11 to 14 weeks. Furthermore, the use of modern ultrasound technology has allowed greater utilization of transabdominal scanning in addition to the transvaginal route. Most major structural heart defects can accurately be diagnosed from the late first trimester of pregnancy and many families at-risk can be reassured of 'normality' of cardiac connections at an early stage. Some lesions may evolve throughout pregnancy and therefore early scans should not replace mid trimester fetal echocardiography.

Limitations of using first-trimester nuchal translucency measurement in routine screening for major congenital heart defects

OBJECTIVE

To evaluate the effectiveness of nuchal translucency (NT) measurement in screening for major congenital heart disease (CHD) in chromosomally normal fetuses.

DESIGN

A population based cohort study of all women having fetal NT measurement at 10-14 weeks of gestation in an unselected population over a 3-year period. The outcome measure was the identification of major CHD in chromosomally normal pregnancies either antenatally or postnatally.

RESULTS

Major defects of the heart and great arteries were identified in 26 out of 7339 pregnancies (prevalence 3.5 per 1000 pregnancies). Out of 26 cases, only four (sensitivity 15.4%, 95% CI 4-35) were in the group of 258 pregnancies (3.5%) with increased NT of > or = 2.5 mm. The prevalence of major CHD increased from 3.1 per 1000 for NT < 2.5 mm to 50 per 1000 for NT > or = 3.5 mm (likelihood ratio of 14.1, 95% CI 4.2-47.9). The positive and negative predictive values for NT > or = 2.5 mm were 1.6% and 99.7%, respectively.

CONCLUSIONS

The prevalence of major CHD in this study was 3.5 per 1000, suggesting that ascertainment of CHD in our study population was thorough. Fetuses with NT measurements > or = 3.5 mm have a significantly increased risk of major CHD, and this identifies a subgroup of high-risk patients in whom early fetal echocardiography would be advocated. The low sensitivity of NT for major CHD in the general population, however, indicates that NT cannot be relied on as the sole or major screening tool for this condition as previously reported.

Does a ?notched? nuchal translucency indicate Down syndrome fetuses or other adverse pregnancy outcome?

The aim of the present study was to assess the sonographic contour of the increased nuchal translucency (NT) and to correlate this with pregnancy outcome. Fifty sonographic images of fetuses with increased NT [> 95th centile thickness of the normal range for crown-rump length (CRL) between 38 and 84 mm] were retrospectively assessed. In all the cases a complete pregnancy and even infancy follow-up (< 36 months) was available. The NT appearances were subdivided into two forms: a 'notched' or 'uniform' appearance. The images were correlated with karyotype results [trisomy 21 (DS) vs euploid cases] and pregnancy outcome. Complicated outcomes were classified as being either DS fetuses, miscarriage or termination of pregnancy because of structural anomaly. Thus 30/35 (86%) of the euploid fetuses had a 'uniformly' increased NT, whereas 8/13 DS cases (62%) had a 'notched' appearance (Fisher's exact test, p = 0.004). Additionally, 27/29 fetuses (93%) which had an uneventful pregnancy outcome had a 'uniform' increased NT, whereas 12/26 (57%) of the fetuses which had adverse pregnancy outcome had a 'notched' appearance of their NT (Fisher's exact test, p < 0.001). Although it was not possible to correlate the sonographic data with post-evacuation microdissection findings, it is possible that a uniformly shaped, increased NT may be more representative of a developmental delay in a normal fetus. Conversely, a 'notched' nuchal surface may represent abnormal lymphatic or cardiovascular development more commonly seen in DS fetuses.

Early screening for fetal cardiac anomalies by transvaginal echocardiography in an unselected population: the role of operator experience

OBJECTIVES

To examine the accuracy of early transvaginal fetal echocardiography performed in an unselected population by operators with different levels of experience and to compare the results with those obtained from a referral population.

DESIGN

Prospective study.

METHODS

A series of 4785 unselected fetuses and 221 referred fetuses were screened at 13-15 weeks' gestational age by transvaginal echocardiography. For each fetus, visualization of the four-chamber view plus the origin of the great arteries was attempted. Color Doppler imaging was only performed in cases of cardiac malformations already identified by two-dimensional echocardiography. The scans were performed by seven operators with different levels of experience. Reliability was assessed by conventional transabdominal echocardiography at 20-22 weeks, by postnatal follow-up in the first 3 months of life, and/or by autopsy in all cases of termination or fetal death.

RESULTS

The rate of complete visualization (four-chamber view plus great arteries) was 47.5% in the unselected population, and 76.9% in the referral population. There were four (0.08%) true positives among the unselected fetuses, and five (2.3%) among referrals, mostly with enlarged nuchal translucency or other malformations. Among the unselected fetuses, nine false negatives were detected by transabdominal echocardiography. Improvement in the operators' ability to recognize cardiac anomalies in unselected population was disappointing and was influenced more by individual approach than by the number of examinations performed.

CONCLUSIONS

Early screening for cardiac anomalies among unselected fetuses is ill-advisable. The usefulness of an early approach is confirmed in high risk fetuses or in the presence of enlarged nuchal translucency when performed by expert operators.

Fetal cardiology

The prevalence of congenital heart disease increases with increasing NT, and many defects can be detected by echocardiography performed by a specialist at 13 to 17 weeks. There is increasing evidence that a prenatal diagnosis improves fetal outcome. Physiology and pathophysiology of the human fetal pulmonary circulation play an important role in the fetal circulation, and recent studies about the reactivity of these vessels in the third trimester have contributed to increase our understanding. The main issue in fetal arrhythmias (brady- and tachycardia) is the correct indication, efficacy, and safety of treatment.

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.

Pregnancy outcome and infant follow-up of fetuses with abnormally increased first trimester nuchal translucency

The numbers of fetuses with an abnormal increased first trimester nuchal translucency (NT) but a confirmed normal anatomy and karyotyping is relatively small and therefore a challenge for prenatal counselling. The aim of the current study was to assess the long-term pregnancy outcome and infancy prognosis of 78 fetuses with NT > 95th centile of the normal range for crown-rump length (CRL). The most common abnormalities in this group were aneuploidy, which affected 32 of the fetuses followed by four and three cases which were miscarried or had cardiac defects respectively. The remaining euploid fetuses with normal detailed scans were followed throughout their infancy (mean 24 months; range 12-36 months). Post-natally, except for a correctable case of ventricular septal defect and a case of posterior urethral valve, no other abnormalities were detected. After excluding all aneuploid cases and using the maternal age as a second variable, an uncomplicated pregnancy outcome could be anticipated in 17 cases (100%) when the maternal age was <30 years and NT between 95th centile and 5 mm. However, the chance of a normal outcome dropped to 50% in four cases with maternal age > or =30 years and NT > or =5 mm (Fisher's exact test; P: = 0.02). These findings suggest that the long-term prognosis of the euploid fetuses with large NT (<5 mm) is reassuring in younger women.

The 11-14 week scan

Fetal nuchal translucency thickness (NT) at the 11-14 week scan has been combined with maternal age to provide an effective method of screening for trisomy 21; for an invasive testing rate of 5%, about 75% of trisomic pregnancies can be identified. When maternal serum free-beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A at 11-14 weeks are also taken into account, the detection rate of chromosomal defects is about 90%. Increased NT can also identify a high proportion of other chromosomal abnormalities and is associated with major defects of the heart and great arteries, and a wide range of skeletal dysplasias and genetic syndromes. Other benefits of the 11-14 week scan include early diagnosis of major fetal defects and the detection of multiple pregnancies, as well as reliable identification of chorionicity. As with the introduction of any new technology into routine clinical practice, it is essential that those undertaking the 11-14 week scan are adequately trained and that their results are subjected to rigorous audit.

Parvovirus as a differential diagnosis of hydrops fetalis in the first trimester

We report a case of fetal parvovirus B19 infection which appears to have resulted in hydrops in the first trimester. An ultrasound scan performed at the booking visit of a woman in the first trimester showed generalised oedema. Karyotyping to exclude a fetal abnormality was normal. Maternal radioimmunoassay serological investigations showed parvovirus B19 IgG and IgM. Post-mortem analysis revealed intranuclear inclusion bodies typical of parvovirus in the erythroid cells in the liver and in the myocardium.

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 screening for fetal abnormalities

The debate over the application of nuchal translucency measurement in Down's syndrome screening is still unresolved in some clinicians' minds. Although different authors report a range of sensitivities for Down's syndrome, none question the validity of the association between increased nuchal translucency and fetal aneuploidy. The published literature reveals a lack of congruence over a standard, reproducible method for measuring nuchal translucency. Only with the adoption of uniform methodology, and the establishment of international standards for nuchal translucency measurement, is the true potential of this test likely to be realized. The increasing use of first trimester ultrasound has focused attention on the value of this investigation in confirming fetal viability, estimation of gestational age, and screening for congenital abnormality. This review summarizes the role of ultrasound and maternal serum biochemistry in first trimester screening.

Pregnancy outcome and nuchal translucency measurements in fetuses with a normal karyotype

The aim of this study was to examine the relationship between nuchal translucency thickness and pregnancy and fetal outcome in fetuses with a normal karyotype and without structural malformations. Fetal nuchal translucency measurements were performed in 2088 chromosomally and structurally normal fetuses. In all fetuses the karyotype and pregnancy outcome were known. Likelihood ratios for different outcome measures were calculated. Spontaneous abortion, intra-uterine and neonatal death occurred in 2.4, 1.1 and 0.5 per cent respectively. The incidence of immature delivery was 1.1 per cent and of premature delivery 6.0 per cent. The only adverse pregnancy outcome recorded that was associated with increased nuchal translucency was spontaneous abortion. The likelihood ratio for the occurrence of a spontaneous abortion was 3.1 for measurements between 3.0 and 3.9 mm, and 6.8 for measurements>/=4 mm. Increased lethality in fetuses with enlarged nuchal translucency and normal chromosomes may provide evidence that the same insult causing excessive fluid collection in the nuchal region may also be responsible for fetal demise.

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.

Screening for fetal aneuploidies and fetal cardiac abnormalities by nuchal translucency thickness measurement at 10-14 weeks of gestation as part of routine antenatal care in an unselected population

OBJECTIVES

To evaluate first trimester pregnancy screening for fetal aneuploidy and congenital heart defects by maternal age and nuchal translucency measurement and screening for fetal aneuploidies and congenital heart defects by ultrasound in an unselected population.

DESIGN

A prospective study.

SETTING

Fetal medicine unit, St George's Hospital, London.

SAMPLE

4523 consecutive viable fetuses at 10-14 weeks with a crown-rump length between 38 and 80 mm were scanned transabdominally (93%) or transvaginally (7%).

METHODS

Screening was performed by calculating the background risk from maternal age, gestational age and obstetric history, which was then adjusted with the nuchal translucency measurement in relation to crown-rump length (adjusted risk).

MAIN OUTCOME MEASURES

Measurements of crown-rump length and nuchal translucency thickness. An adjusted risk of > 1:270 was considered as a positive screening test. Pregnancy outcome was obtained through karyotyping, outcome questionnaires and examination of the newborn infants.

RESULTS

Mean maternal age was 29-4 years and mean gestational age 12.2 weeks. Screening was positive in 230/4523 fetuses (5.1%), when the adjusted risk (mean 1:2649) was > 1:270. Fetal karyotype was abnormal in 23 (0.51%) cases, including twelve with trisomy 21, five trisomy 18, one trisomy 13, one trisomy 10, one monosomy X and two triploidies. For a false positive rate of 4.7%, the sensitivity of this test was 78% in detecting any fetal aneuploidy. Only one out of nine major congenital heart defects in this population was found within the 110 euploid fetuses with increased nuchal translucency thickness (> 2.5 mm).

CONCLUSION

Screening for fetal aneuploidy by maternal age and nuchal translucency measurement can be effective in an unselected population. However, our results do not support its effectiveness in the detection of cardiac abnormalities.

Cystic hygroma in the fetus and newborn

Cystic hygromas are developmental abnormalities of the lymphoid system that occur at sites of lymphatic-venous connection, most commonly in the posterior neck. They are frequently associated with karyotypic abnormalities, various malformation syndromes, and several teratogenic agents. The disease course of an infant with cystic hygroma is unpredictable. When diagnosed prenatally, the overall prognosis is poor. Cystic hygroma diagnosed after birth is usually associated with a good prognosis. This article reviews the embryologic, genetic, and pathologic correlates of these lymphatic system abnormalities, as well as the clinical course and outcome of the fetus and newborn with a cystic hygroma. Management strategies are reviewed, including newer nonsurgical therapies for the neonate with a cystic hygroma.

Early diagnosis of major cardiac defects in chromosomally normal fetuses with increased nuchal translucency

OBJECTIVE

To determine the value of early ultrasound examination for prenatal diagnosis of cardiac defects in chromosomally normal fetuses with increased nuchal translucency thickness at 10-14 weeks of gestation.

DESIGN

Prospective audit.

SETTING

Fetal Medicine Centre.

METHODS

Specialist fetal echocardiography was carried out in 398 chromosomally normal fetuses with a nuchal translucency measurement above the 99th centile (> or = 3.5 mm). In the first 75 pregnancies the cardiac scan was carried out at 17-22 weeks and the next 323 cases had one scan at 13-17 weeks and another at 20-22 weeks. Pregnancy outcome was obtained in all of the cases.

RESULTS

Major cardiac defects were present in 29 (7.3% of 398) cases and in 28 of these the diagnosis was made by antenatal echocardiography. In 27 of the 29 fetuses with major cardiac defects echocardiography was carried out at 13-17 weeks and an abnormality was suspected in 24 of the cases (88%).

CONCLUSIONS

Increased nuchal translucency in chromosomally normal fetuses is associated with an increased prevalence of major cardiac defects and, as such, is an indication for specialist fetal echocardiography. Most of the cardiac abnormalities are detectable on antenatal fetal echocardiography and many can be excluded by early scanning.

Smith-Lemli-Opitz syndrome presenting with persisting nuchal oedema and non-immune hydrops

Smith-Lemli-Opitz syndrome (SLO) is a recognized clinical entity with distinctive anomalies. Recently it has been shown that a specific defect in cholesterol metabolism, 7-dehydroxycholesterol reductase deficiency, causes the multiple abnormalities seen in SLO. There have been two reports of first-trimester nuchal translucency associated with SLO. We report two cases of SLO in the third trimester, one with persisting nuchal oedema and the other presenting with hydrops. These findings may explain a proportion of the perinatal loss associated with this syndrome.

Can nuchal cord cause transient increased nuchal translucency thickness?

When detected in a first trimester scan, an increased thickness of nuchal translucency (NT) may be associated with chromosomal, cardiac or genetic disorders. However, less attention has been devoted to the outcome of those fetuses who have confirmed normal anatomies and karyotyping, but have abnormal first trimester scans. Thus, a challenging new issue is how to counsel such cases of transient increased NT in which the translucency rapidly vanishes with no evidence of other underlying abnormalities. Two cases of transient increased thickness of NT are reported. In both, a nuchal cord was ultrasonographically demonstrated and a thorough work-up revealed chromosomally and anatomically normal fetuses. The pathophysiological theories behind these observations and their significance are discussed. Based on these observations, we suggest that transvaginal sonography combined with Doppler flow studies should be utilized for the presize detection of cord patterns to accomplish the work-up in cases of increased NT.

Using fetal nuchal translucency to screen for major congenital cardiac defects at 10-14 weeks of gestation: population based cohort study

OBJECTIVES

To examine the utility of measuring fetal nuchal translucency thickness in screening for major defects of the heart and great arteries at 10-14 weeks of gestation.

DESIGN

Population based cohort study.

SUBJECTS

29 154 singleton pregnancies with chromosomally normal fetuses at 10-14 weeks of gestation.

SETTING

Fetal medicine centre in London.

MAIN OUTCOME MEASURE

Prevalence of major defects of the heart and great arteries.

RESULTS

Of 50 cases with major defects of the heart and great arteries (prevalence 1.7 per 1000 pregnancies) 28 (56%, 95% confidence interval 42% to 70%) were in the subgroup of 1822 pregnancies with fetal nuchal translucency thicknesses above the 95th centile of the normal range. The positive and negative predictive values for this cut off point of nuchal translucency thickness were 1.5% and 99.9% respectively.

CONCLUSIONS

Measurement of fetal nuchal translucency thickness-traditionally used to identify fetuses at high risk of aneuploidy-at 10-14 weeks of gestation can identify a large proportion of fetuses with major defects of the heart and great arteries.

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.

Prenatal sonographic diagnosis of Cantrell's pentalogy with cystic hygroma in the first trimester

We report 2 cases of Cantrell's pentalogy with cystic hygroma diagnosed in the first trimester of pregnancy. Both fetuses had ectopia cordis, omphalocele, a sternal defect, and cystic hygroma detected by sonography. Cystic hygroma may be another characteristic of Cantrell's pentalogy in the first trimester.

UK multicentre project on assessment of risk of trisomy 21 by maternal age and fetal nuchal-translucency thickness at 10-14 weeks of gestation. Fetal Medicine Foundation First Trimester Screening Group

BACKGROUND

Prenatal diagnosis of trisomy 21 currently relies on assessment of risk followed by invasive testing in the 5% of pregnancies at the highest estimated risk. Selection of the high-risk group by a combination of maternal age and second-trimester maternal serum biochemistry gives a detection rate of about 60%. We investigated assessment of risk by a combination of maternal age and fetal nuchal-translucency thickness, measured by ultrasonography at 10-14 weeks of gestation.

METHODS

The risk of trisomy 21 was estimated for 96127 women of median age 31 years (range 14-49) with singleton pregnancies. Ultrasonography was done by 306 appropriately trained sonographers in 22 centres. Risk of trisomy 21 was calculated from the maternal age and gestational-age-related prevalence, multiplied by a likelihood ratio depending on the deviation from normal in nuchal-translucency thickness for crown-rump length. The distribution of risks was investigated and the sensitivity of a cut-off risk of 1 in 300 was calculated. Phenotype was assessed by fetal karyotyping or clinical examination of liveborn infants.

FINDINGS

The estimated trisomy-21 risk, from maternal age and fetal nuchal-translucency thickness, was 1 in 300 or higher in 7907 (8.3%) of 95476 normal pregnancies, 268 (82-2%) of 326 with trisomy 21, and 253 (77.9%) of 325 with other chromosomal defects. The 5% of the study population with the highest estimated risk included 77% of trisomy-21 cases.

INTERPRETATION

Selection of the high-risk group for invasive testing by this method allows the detection of about 80% of affected pregnancies. However, even this method of risk assessment requires about 30 invasive tests for identification of one affected fetus.

First-trimester transabdominal fetal echocardiography

BACKGROUND

Fetal echocardiography is usually done during the second trimester of pregnancy, but waiting until that time can lead to anxiety for the parents if the fetus is at high risk of having cardiac abnormalities. We report the feasibility of transabdominal first-trimester fetal echocardiography for early reassurance of normality or a prenatal diagnosis of a cardiac malformation.

METHODS

We did first-trimester fetal echocardiography and colour-flow mapping with a 5 MHz curvilinear transducer at 13 weeks' gestation (range 12-13+6 days) in 15 fetuses at risk of cardiac defects. The fetus was judged to be normal if the investigation showed normal visceral situs, four-chamber view, and two normally related great arteries of similar size. We did second-trimester scans and neonatal follow-up for the women who continued with their pregnancies; necropsy was done in two cases of pregnancy termination.

FINDINGS

Ten fetuses had normal hearts at the time of the first scan, which was confirmed during second-trimester assessment. In one fetus, the four-chamber view was asymmetrical and a moderate-sized apical muscular ventricular septal defect (VSD) was diagnosed after birth. In another two fetuses we diagnosed small muscular VSD on the second-trimester scans. A complex cardiac malformation was correctly diagnosed in one fetus at 12 weeks of gestation. Thus, in 11 fetuses, the imaging was of sufficient quality to reassure the family or to diagnose an abnormality. In the other four fetuses, the investigation was judged to be incomplete, but no definite cardiac abnormality was identified.

INTERPRETATION

Transabdominal fetal echocardiography in the first trimester of pregnancy is feasible. In most patients the resolution of images is sufficient to allow assessment of basic cardiac anatomy, when normal, or detection of complex malformations, when present.

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.