Interaction between clinicians and artificial intelligence to detect fetal atrioventricular septal defects on ultrasound: how can we optimize collaborative performance?

OBJECTIVES: Artificial intelligence (AI) has shown promise in improving the performance of fetal ultrasound screening in detecting congenital heart disease (CHD). The effect of giving AI advice to human operators has not been studied in this context. Giving additional information about AI model workings, such as confidence scores for AI predictions, may be a way of further improving performance. Our aims were to investigate whether AI advice improved overall diagnostic accuracy (using a single CHD lesion as an exemplar), and to determine what, if any, additional information given to clinicians optimized the overall performance of the clinician-AI team. METHODS: An AI model was trained to classify a single fetal CHD lesion (atrioventricular septal defect (AVSD)), using a retrospective cohort of 121 130 cardiac four-chamber images extracted from 173 ultrasound scan videos (98 with normal hearts, 75 with AVSD); a ResNet50 model architecture was used. Temperature scaling of model prediction probability was performed on a validation set, and gradient-weighted class activation maps (grad-CAMs) produced. Ten clinicians (two consultant fetal cardiologists, three trainees in pediatric cardiology and five fetal cardiac sonographers) were recruited from a center of fetal cardiology to participate. Each participant was shown 2000 fetal four-chamber images in a random order (1000 normal and 1000 AVSD). The dataset comprised 500 images, each shown in four conditions: (1) image alone without AI output; (2) image with binary AI classification; (3) image with AI model confidence; and (4) image with grad-CAM image overlays. The clinicians were asked to classify each image as normal or AVSD. RESULTS: A total of 20 000 image classifications were recorded from 10 clinicians. The AI model alone achieved an accuracy of 0.798 (95% CI, 0.760-0.832), a sensitivity of 0.868 (95% CI, 0.834-0.902) and a specificity of 0.728 (95% CI, 0.702-0.754), and the clinicians without AI achieved an accuracy of 0.844 (95% CI, 0.834-0.854), a sensitivity of 0.827 (95% CI, 0.795-0.858) and a specificity of 0.861 (95% CI, 0.828-0.895). Showing a binary (normal or AVSD) AI model output resulted in significant improvement in accuracy to 0.865 (P < 0.001). This effect was seen in both experienced and less-experienced participants. Giving incorrect AI advice resulted in a significant deterioration in overall accuracy, from 0.761 to 0.693 (P < 0.001), which was driven by an increase in both Type-I and Type-II errors by the clinicians. This effect was worsened by showing model confidence (accuracy, 0.649; P < 0.001) or grad-CAM (accuracy, 0.644; P < 0.001). CONCLUSIONS: AI has the potential to improve performance when used in collaboration with clinicians, even if the model performance does not reach expert level. Giving additional information about model workings such as model confidence and class activation map image overlays did not improve overall performance, and actually worsened performance for images for which the AI model was incorrect. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Unusual Vascular Ring in the Fetus.

We present the clinical course and echocardiographic and genetic findings of two fetuses with an unusual vascular ring, created by a left aortic arch with a right arterial duct and an aberrant right subclavian artery. One fetus was diagnosed with 22q11.2 microdeletion and the other became symptomatic in infancy. It is important to consider the position of the arterial ductal ligament in patients who present with tracheoesophageal compressive symptoms in the presence of a left aortic arch. These cases also highlight that a vascular ring formed from a left arch may have similar associations to a vascular ring formed by a right aortic arch.

Impact of prospective measurement of outflow tracts in prediction of coarctation of the aorta.

OBJECTIVES: Prenatal diagnosis of coarctation of the aorta (CoA) is associated with reduced mortality and morbidity, however, accurate prenatal prediction remains challenging. To date, studies have used retrospective measurements of the outflow tracts to evaluate their potential to predict CoA. Our primary objective was to evaluate prospectively acquired measurements of the outflow tracts in fetuses with prenatally suspected CoA. A secondary aim was to report the postnatal prevalence of bicuspid aortic valve in this cohort. METHODS: Pregnancies with suspicion of isolated CoA and with a minimum of 6 months' postnatal follow-up available were identified from the cardiac database of a tertiary fetal cardiology center in the UK, between January 2002 and December 2017. Measurement of the aortic valve, pulmonary valve, distal transverse aortic arch (DTAA) and arterial duct (AD) diameters were undertaken routinely in fetuses with suspected CoA during the study period. Z-scores were computed using published reference ranges based on > 7000 fetuses from our own unit. RESULTS: Of 149 pregnancies with prenatally suspected CoA included in the study, CoA was confirmed within 6 months after birth in 77/149 (51.7%) cases. DTAA diameter Z-score and the Z-score of second-trimester DTAA/AD diameter ratio were smaller in fetuses with postnatally confirmed CoA than those in false-positive cases (-2.8 vs -1.9; P = 0.039 and -3.13 vs -2.61; P = 0.005, respectively). Multiple regression analysis demonstrated that the Z-scores of DTAA and AD diameters were the only significant predictors of postnatal CoA (P = 0.001). Bicuspid aortic valve was identified in 30% of the false-positive cases. CONCLUSIONS: Measurement of DTAA and AD diameter Z-scores can be used to ascertain risk for postnatal CoA in a selected cohort. The high incidence of bicuspid aortic valve in false-positive cases merits further study with respect to both etiology and longer-term significance. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

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

OBJECTIVE: To examine the association between fetal major heart defects and increased nuchal translucency thickness (NT), tricuspid regurgitation and abnormal flow in the ductus venosus in a large population of singleton pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation. METHODS: This was a retrospective study of prospectively collected data from singleton pregnancies attending for a routine ultrasound scan at 11-13 weeks' gestation, which included examination of fetal anatomy, measurement of NT and assessment of blood flow across the tricuspid valve and in the ductus venosus, according to a standardized protocol. The incidence of fetal NT ≥ 95th and ≥ 99th percentiles, tricuspid regurgitation and reversed a-wave in the ductus venosus in fetuses with and those without a major heart defect was determined and the performance of each marker and their combination in the detection of major heart defects was calculated. RESULTS: The study population of 93 209 pregnancies with no apparent chromosomal abnormality included 211 (0.23%) with a fetal major heart defect and 92 998 morphologically normal neonates. In 113 (53.6%) cases with a major heart defect, the diagnosis was made at the 11-13-week scan, in 82 (38.9%) at the 18-24-week scan, in 10 (4.7%) at the third-trimester scan and in six (2.8%) postnatally. At the 11-13-week scan, we diagnosed all cases of tricuspid or pulmonary atresia and polyvalvular dysplasia, > 90% of cases of hypoplastic left heart syndrome or atrioventricular septal defect, about 60% of complex heart defects and cases of left atrial isomerism (interrupted inferior vena cava with normal intracardiac anatomy), 30-40% of cases of tetralogy of Fallot and arch abnormalities, 25% of tricuspid valve abnormalities and about 15% of cases of transposition of the great arteries, but none of aortic or pulmonary stenosis or common arterial trunk. Fetal NT ≥ 95th or ≥ 99th percentile, tricuspid regurgitation or abnormal ductus venosus flow was observed in 77 (36.5%), 45 (21.3%), 61 (28.9%) and 58 (27.5%) fetuses with a major heart defect, respectively, and in 5678 (6.1%), 857 (0.9%), 1136 (1.2%) and 1644 (1.8%) of those without a heart defect. Any one of NT ≥ 95th percentile, tricuspid regurgitation or abnormal flow in the ductus venosus was found in 117 (55.5%; 95% CI, 48.5-62.3%) fetuses with a heart defect and in 8166 (8.8%; 95% CI, 8.6-9.0%) of those without a heart defect. Any one of NT ≥ 99th percentile or the other two markers was found in 99 (46.9%; 95% CI, 40.0-53.9%) fetuses with a heart defect and in 3517 (3.8%; 95% CI, 3.7-3.9%) of those without a heart defect. CONCLUSION: At 11-13 weeks' gestation, measurement of fetal NT and assessment of flow across the tricuspid valve and in the ductus venosus can lead to early diagnosis of major heart defect. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Diagnosis of fetal non-chromosomal abnormalities on routine ultrasound examination at 11-13 weeks' gestation.

OBJECTIVE: To examine the performance of the routine 11-13-week scan in detecting fetal non-chromosomal abnormalities. METHODS: This was a retrospective study of prospectively collected data from 100 997 singleton pregnancies attending for a routine ultrasound examination of fetal anatomy, performed according to a standardized protocol, at 11-13 weeks' gestation. All continuing pregnancies had an additional scan at 18-24 weeks and 71 754 had a scan at either 30-34 or 35-37 weeks. The final diagnosis of fetal abnormality was based on the results of postnatal examination in cases of live birth and on the findings of the last ultrasound examination in cases of pregnancy termination, miscarriage or stillbirth. The performance of the 11-13-week scan in the detection of fetal abnormalities was determined. RESULTS: The study population contained 1720 (1.7%) pregnancies with a fetal abnormality, including 474 (27.6%) detected on the first-trimester scan, 926 (53.8%) detected on the second-trimester scan and 320 (18.6%) detected in the third trimester or postnatally. At 11-13 weeks' gestation, we diagnosed all cases of acrania, alobar holoprosencephaly, encephalocele, tricuspid or pulmonary atresia, pentalogy of Cantrell, ectopia cordis, exomphalos, gastroschisis and body-stalk anomaly and > 50% of cases of open spina bifida, hypoplastic left heart syndrome, atrioventricular septal defect, complex heart defect, left atrial isomerism (interrupted inferior vena cava with normal intracardiac anatomy), lower urinary tract obstruction, absence of extremities, fetal akinesia deformation sequence and lethal skeletal dysplasia. Common abnormalities that were detected in < 10% of cases at 11-13 weeks included ventriculomegaly, agenesis of the corpus callosum, isolated cleft lip, congenital pulmonary airway malformation, ventricular septal defect, abdominal cysts, unilateral renal agenesis or multicystic kidney, hydronephrosis, duplex kidney, hypospadias and talipes. CONCLUSIONS: A routine 11-13-week scan, carried out according to a standardized protocol, can identify many severe non-chromosomal fetal abnormalities. A summary statistic of the performance of the first-trimester scan is futile because some abnormalities are always detectable, whereas others are either non-detectable or sometimes detectable. To maximize prenatal detection of abnormalities, additional scans in both the second and third trimesters are necessary. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Diagnóstico de anomalías fetales no cromosómicas en la ecografía de rutina a las 11-13 semanas de gestación OBJETIVO: Examinar el desempeño de la ecografía de rutina a las 11-13 semanas en la detección de anomalías fetales no cromosómicas. MÉTODOS: Esta investigación fue un estudio retrospectivo de datos recogidos prospectivamente de 100 997 embarazos con feto único que acudieron a un examen ecográfico de rutina de la anatomía fetal, realizado de acuerdo con un protocolo estandarizado, a las 11-13 semanas de gestación. Todos los embarazos que continuaron se sometieron a una exploración adicional a las 18-24 semanas y 71754 se sometieron a una exploración a las 30-34 o a las 35-37 semanas. El diagnóstico final de la anomalía fetal se basó en los resultados del examen postnatal en los casos de nacimientos vivos y en los hallazgos del último examen ecográfico en los casos de interrupción del embarazo, aborto o éxitus fetal. Se determinó el rendimiento de la exploración de las 11-13 semanas en la detección de anomalías fetales. RESULTADOS: La población del estudio contenía 1720 (1,7%) embarazos con una anormalidad fetal, entre ellos 474 (27,6%) detectados en la exploración del primer trimestre, 926 (53,8%) detectados en la del segundo trimestre y 320 (18,6%) detectados en el tercer trimestre o postnatalmente. A las 11-13 semanas de gestación, se diagnosticaron todos los casos de acrania, holoprosencefalia alobar, encefalocele, atresia tricúspide o pulmonar, pentalogía de Cantrell, ectopia cordis, onfalocele, gastrosquisis y anomalía del pedículo embrionario y >50% de los casos de espina bífida abierta, síndrome del hemicardio izquierdo hipoplásico, comunicación auriculoventricular, defecto cardíaco complejo, isomerismo de la aurícula izquierda (vena cava inferior interrumpida con anatomía intracardíaca normal), obstrucción del tracto urinario inferior, ausencia de extremidades, secuencia de deformación de la acinesia fetal y displasia esquelética letal. Las anomalías comunes que se detectaron en <10% de los casos a las 11-13 semanas incluyeron ventriculomegalia, agenesia del cuerpo calloso, labio leporino aislado, malformación congénita de las vías respiratorias pulmonares, comunicación interventricular, quistes abdominales, agenesia renal unilateral o riñón multiquístico, hidronefrosis, duplicidad renal, hipospadias y pie zambo. CONCLUSIÓN: Una exploración rutinaria a las 11-13 semanas, realizada de acuerdo con un protocolo estandarizado, puede identificar muchas anomalías fetales no cromosómicas graves. Un resumen estadístico del desempeño de la exploración del primer trimestre es inútil porque algunas anomalías son siempre detectables, mientras que otras no lo son o solo lo son a veces. Para maximizar la detección prenatal de anormalidades, se necesitan exploraciones adicionales tanto en el segundo como en el tercer trimestre.

Fetuses with right aortic arch: a multicenter cohort study and meta-analysis.

OBJECTIVES: Use of recent antenatal screening guidelines for cardiac abnormalities has increased fetal diagnoses of right aortic arch (RAA). We aimed to establish the outcome of fetal RAA without intracardiac abnormalities (ICA) to guide postnatal management. METHODS: In the retrospective cohort part of our study, outcome measures were rates of chromosomal abnormalities, 22q11.2 deletion, fetal extracardiac abnormalities (ECA), postnatal ICA and ECA, and symptoms of and surgery for vascular ring. A systematic review and meta-analysis was also performed; results are reported as proportions. Kaplan-Meier analysis of vascular ring cases with surgery as endpoint was performed. RESULTS: Our cohort included 86 cases; 41 had a vascular ring. Rates of chromosomal abnormalities, 22q11.2 deletion and fetal ECA were 14.1%, 6.4% and 17.4%, respectively. Sixteen studies including our cohort (312 fetuses) were included in the systematic review. Overall rates of chromosomal abnormalities and 22q11.2 deletion were 9.0% (95% CI, 6.0-12.5%) and 6.1% (95% CI, 3.6-9.3%), whilst the respective rates for cases with no ECA were 4.6% (95% CI, 2.3-7.8%) and 5.1% (95% CI, 2.4-8.6%). ECA were seen in 14.6% (95% CI, 10.6-19.0%) prenatally and in 4.0% (95% CI, 1.5-7.6%) after birth. Postnatal ICA were identified in 5.0% (95% CI, 2.7-7.9%). Rate of symptoms of vascular rings (follow-up ≥ 24 months postpartum) was 25.2% (95% CI, 16.6-35.0%), and 17.1% (95% CI, 9.9-25.7%) had surgery. Two-year freedom from surgery was 83.0% (95% CI, 74.3-90.1%). CONCLUSIONS: Fetal RAA without ICA is more frequently associated with ECA than with chromosomal abnormalities. Most cases, however, are isolated. Vascular-ring symptoms occur in about 25% of cases. Postnatal surveillance is required mainly in the first 2 years after delivery.

Assessment of cardiac angle in fetuses with congenital heart disease at risk of 22q11.2 deletion.

OBJECTIVES: To evaluate fetal cardiac angle as a screening tool for 22q11.2 deletion among cases with cardiac anomalies known to be associated with this genetic condition, to examine the correlation of fetal cardiac angle with thymic-thoracic (TT)-ratio, and to assess the performance of TT ratio as a covariate in screening for 22q11.2 deletion. METHODS: This was a retrospective cohort study that reviewed the records of 74 cases with cardiac anomalies known to be associated with 22q11.2 deletion (tetralogy of Fallot, common arterial trunk, interrupted aortic arch and right aortic arch) that were diagnosed between 2007 and 2013. The karyotype was known in all cases. The fetal cardiac angle and TT-ratio were measured using stored three-dimensional spatiotemporal image correlation volume datasets and compared in those with del.22q11.2 and those without. RESULTS: Of the 74 cases reviewed, 16 had 22q11.2 deletion. The mean cardiac angle was larger in the cases with 22q11.2 deletion than in those without (68.6° vs 58.7°, respectively; P = 0.02). Multivariate regression analysis showed an association between cardiac angle and TT-ratio in fetuses with 22q11.2 deletion (r(2) = 0.33; P = 0.02) but not in those with a normal karyotype (P = 0.4). Logistic regression analysis demonstrated that fetal cardiac angle, but not TT-ratio, is an independent predictor of 22q11.2 deletion among fetuses with 22q11.2 deletion-associated cardiac anomalies (P = 0.02; area under the receiver-operating characteristics curve = 0.69). CONCLUSIONS: An enlarged fetal cardiac angle is an independent predictor of 22q11.2 deletion among fetuses with 22q11.2 deletion-associated cardiac anomalies. However, its performance as a single variable in a screening model is not sufficient to guide management decisions regarding invasive testing.

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

OBJECTIVE: To document outcome following prenatal diagnosis of ventricular septal defects (VSDs), particularly associated anomalies and the requirement for surgical closure of the defect. METHODS: All cases of prenatal diagnosis of a VSD made by fetal cardiologists at a tertiary fetal medicine referral center in the period January 2002 to December 2011 were extracted from our database. Data regarding fetal cardiac diagnosis, extracardiac anomalies, nuchal translucency thickness and karyotype were noted. RESULTS: A total of 171 cases fulfilled our selection criteria. Of these, 69% were diagnosed with a perimembranous VSD and 31% with a muscular defect. The median gestational age at diagnosis was 21 + 6 (range, 12 + 0 to 37 + 3) weeks. Owing to severe extracardiac or genetic conditions, pregnancy resulted in intrauterine death or termination in 49% cases, and postnatal death occurred in 9% of cases. Seventy-two babies were liveborn, and were regarded as potential surgical candidates if hemodynamics suggested that surgery was indicated. Surgical closure of the VSD proved necessary in 50% of the patients with a perimembranous VSD and 13% of those with a muscular VSD. All patients operated on survived surgical repair. No karyotypic abnormalities were identified in fetuses with VSDs that had normal first-trimester screening and no other sonographic abnormalities. CONCLUSIONS: A high proportion of VSDs diagnosed during fetal life (29%) require postnatal surgical intervention. The assessment of hemodynamic significance from fetal echocardiography is imperfect. The presence of extracardiac abnormalities or abnormal results on first-trimester screening has a major impact on the incidence of karyotypic abnormalities in affected fetuses. This should inform discussions with parents about invasive testing.

Reliability of fetal thymus measurement in prediction of 22q11.2 deletion: a retrospective study using four-dimensional spatiotemporal image correlation volumes.

OBJECTIVES: To evaluate the thymic-thoracic ratio (TT-ratio) method in assessment of the fetal thymus in normal fetuses and in those with cardiac abnormalities, in the presence or absence of 22q11.2 deletion. METHOD: Database records were reviewed for cases of conotruncal and arch abnormalities found on fetal echocardiography between January 2007 and September 2011. The 22q11.2 deletion status was retrieved and cases in which this was not known were excluded from the analysis, as were fetuses with aneuploidy or other genetic disorders. An additional 55 normal fetuses were analyzed as a control group. The TT-ratio was measured retrospectively using stored spatiotemporal image correlation (STIC) volume datasets. RESULTS: Sixty-nine fetuses with relevant cardiac diagnoses were identified and, of these, 18 (26%) had 22q11.2 deletion. The mean gestational age at diagnosis was 22 weeks. Significant pairwise differences, but also overlap, were observed between all three groups (i.e. fetuses with heart defects with and without the 22q11.2 deletion and controls). The mean TT-ratio was 0.44 in our normal control group and was significantly smaller in fetuses with 22q11.2 deletion, corresponding to previously published data. However, the mean TT-ratio in the group with conotruncal anomalies but without the 22q11.2 deletion was also smaller than that in controls, in contrast to previously published data. The TT-ratio was above the normal mean, regardless of fetal karyotype, in all cases of interrupted aortic arch. CONCLUSION: The TT-ratio method is a feasible and potentially useful tool during detailed fetal heart assessment. However, the absolute measurement is not reliable for prediction of 22q11.2 deletion and the obtained results should therefore be interpreted with caution. Fetal karyotyping should be recommended in cases with conotruncal heart abnormalities, irrespective of the TT-ratio.

Comparison of echocardiographic findings in fetuses at less than 15 weeks' gestation with later cardiac evaluation.

OBJECTIVE: To compare the echocardiographic findings in fetuses at < 15 weeks' gestation with a later follow-up scan, and determine both the accuracy of early diagnosis and the frequency of findings that change between scans. METHODS: For the period 2002 to the end of 2009, we searched our database for all patients who had had a detailed fetal echocardiogram at less than 15 completed weeks' gestation and a repeat scan at least 6 weeks later. RESULTS: Of 1200 patients fulfilling our selection criteria, the cardiac findings were normal at both scans in 1069. In 46 cases the same cardiac abnormality was seen at both scans. There was a false-positive diagnosis at early scan in seven cases. In 50 cases, there were mildly abnormal functional findings early in pregnancy with no abnormality found later. In 29 fetuses, there was discordance between the early and later morphological diagnosis, 15/29 being considered significant differences, with 10/15 representing true progression of findings between the early and later scans, rather than missed or incorrect diagnoses. CONCLUSIONS: A high degree of accuracy in the identification of congenital heart disease can be achieved by early fetal echocardiography (sensitivity 84.8 (95% CI, 75.0-91.9)%, specificity 95.3 (95% CI, 93.9-96.4)%), although the identification of every case of tetralogy of Fallot and small atrioventricular septal defects presents particular diagnostic challenges at this gestational age. A small but significant group showed progression of findings during this stage of rapid fetal heart growth, particularly in obstructive lesions.

Three-dimensional fetal echocardiography for prediction of postnatal surgical approach in double outlet right ventricle: a pilot study.

OBJECTIVES: To examine the feasibility of reconstructing three-dimensional (3D) echocardiographic views in fetuses with double outlet right ventricle, which might enhance prognostication with respect to the postnatal surgical approach. METHODS: This was a retrospective blinded observational study. Our database was reviewed from January 2007 to June 2011 to identify fetuses with usual atrial arrangement, concordant atrioventricular connections, double outlet right ventricle and relatively balanced left and right ventricular size. Six fetuses, in which there was an intention to treat, were included. RESULTS: In all six cases, we identified important features, including location of the ventricular septal defect and its relation to the atrioventricular valves and great arteries. The postnatal surgical approach was predicted accurately in each case. CONCLUSION: In this group of fetuses with double outlet right ventricle, detailed evaluation by 3D fetal echocardiography enhanced visualization of the anatomy, leading to accurate prediction of the type of surgical repair. Prospective validation in a large cohort of fetuses is warranted.

Prenatally detectable congenital heart defects in fetuses with Down syndrome.

OBJECTIVE: To document the incidence of congenital heart defects (CHD) that are detectable echocardiographically in the fetus with trisomy 21 and the relationship with nuchal translucency, fetal sex and ethnicity. METHODS: Data on fetuses with a karyotypic diagnosis of trisomy 21 were collected between January 2002 and March 2010. The data were analyzed for the gestational age at examination, maternal age, reason for referral for fetal echocardiography, cardiac diagnosis, fetal sex, ethnicity and outcome. RESULTS: Of 917 fetuses with trisomy 21, 487 had a diagnostic echocardiogram. Cardiac examination was performed before 14 weeks' gestation in 75% of cases. The main reasons for referral were increased nuchal translucency (NT) in 76% of cases, suspected cardiac abnormality in 15% and an extracardiac anomaly in 6%. Structural CHD was found in 164/487 (34%), or 98/412 (24%) if those referred for suspected CHD are removed from the analysis. The most common diagnosis was atrioventricular septal defect (AVSD) (115/487, 24%). The ratio of female to male fetuses with AVSD was 29%:18% (P = 0.003). There was no difference in the incidence of AVSD with ethnicity. The pregnancy continued in 36 cases, but three were lost to follow-up; of the known outcomes there were 10 intrauterine deaths, six of which had structural heart disease, and 23 live births, 15 of which had CHD. CONCLUSION: Most fetuses (66-76%) with trisomy 21 have a structurally normal heart on echocardiography. The presence of structural CHD was not associated with increased NT. The increased incidence of AVSD in females was confirmed in our study, although an ethnic difference could not be confirmed. CHD does not appear to increase the chance of spontaneous intrauterine loss in ongoing pregnancies.

Fetal echocardiography at 11-13 weeks by transabdominal high-frequency ultrasound.

OBJECTIVES: To assess the accuracy of fetal echocardiography at 11-13 weeks performed by well-trained obstetricians using a high-frequency linear ultrasound transducer. METHODS: Fetal echocardiography was performed by obstetricians immediately before chorionic villus sampling for fetal karyotyping at 11-13 weeks. Digital videoclips of the examination stored by the obstetrician were reviewed offline by a specialist fetal cardiologist. RESULTS: The obstetrician suspected 95 (95%) of the 100 cardiac defects identified by the fetal cardiologist and made the correct diagnosis in 84 (84%) of these cases. In 54 fetuses, the defect was classified as major and in 46 it was minor. In 767 (86.6%) cases, the heart was normal and in 19 (2.1%) the views were inadequate for assessment of normality or abnormality. A subsequent second-trimester scan in the normal group identified major cardiac defects in four cases. Therefore, the first-trimester scan by the obstetricians and cardiologists identified 54 (93.1%) of the 58 major cardiac defects. CONCLUSIONS: A well-trained obstetrician using high-resolution ultrasound equipment can assess the fetal heart at 11-13 weeks with a high degree of accuracy.

Isolated single umbilical artery: need for specialist fetal echocardiography?

OBJECTIVE: To examine the association between single umbilical artery (SUA) and cardiac defects and to determine whether patients with SUA require specialist fetal echocardiography. METHODS: Incidence and type of cardiac defects were determined in fetuses with SUA detected at routine second-trimester ultrasound examination. RESULTS: A routine second-trimester scan was performed in 46 272 singleton pregnancies at a median gestation of 22 (range, 18-25) weeks and an SUA was diagnosed in 246 (0.5%). Cardiac defects were diagnosed in 16 (6.5%) of these cases, including 10 (4.3%) in a subgroup of 233 with no other defects and in six (46.2%) of the 13 with multiple defects. In 11 (68.8%) of the 16 cases with cardiac defects the condition was readily diagnosable by evaluating the standard four-chamber view and the views of the great arteries. In the remaining cases there was left persistent superior vena cava or small ventricular septal defect, where prenatal diagnosis may not be important because they are not associated with adverse outcome. CONCLUSION: Although SUA is associated with an increased incidence of cardiac defects it may not be necessary to refer such patients for specialist fetal echocardiography because the defects are detectable by evaluating standard cardiac views that should be part of the routine second-trimester scan.

Aberrant right subclavian artery at 16 to 23 + 6 weeks of gestation: a marker for chromosomal abnormality.

OBJECTIVES: This study was carried out to determine the feasibility of defining the position of the right subclavian artery (RSA) by fetal echocardiography between 16 and 23 weeks of gestation, and the association between an aberrant right subclavian artery (ARSA) and chromosomal and cardiac defects. METHODS: We examined the position of the RSA in all patients who attended our unit for a fetal cardiac scan. The assessment was carried out using a transverse view of the fetal chest sweeping up from the level of the aortic arch, using color flow mapping. An ARSA was diagnosed when this vessel was not seen in the normal position and an arterial vessel was seen crossing behind the trachea towards the right arm, arising as a fourth branch of the aortic arch, at a lower level than normal. RESULTS: The course of the RSA could be identified in more than 95% of the 2799 fetuses examined between 16 and 23 + 6 weeks of gestation. An ARSA was found in 43 fetuses. The incidence was 1.5% in normal fetuses, 28.6% in fetuses with trisomy 21, 18.2% in fetuses with trisomy 18 and 8% in fetuses with other chromosomal defects. There was an association between an ARSA and cardiac defects in seven of the 43 fetuses (16%), and three of these seven fetuses had a normal karyotype. CONCLUSIONS: Assessment of the RSA by a fetal cardiologist is possible in almost all cases. The finding of an ARSA is much more common in fetuses with chromosomal defects, in particular trisomy 21 (where the prevalence of an ARSA was 29%), compared with euploid fetuses. Moreover, the presence of an ARSA may be associated with an increased incidence of intracardiac malformations. Examination of the position of the RSA is likely to become a routine ultrasound marker for chromosomal abnormalities in the second trimester of pregnancy.