First-trimester fetal echocardiography: is the future now?

Feasibility and Accuracy of Early Fetal Echocardiography Performed at 13+0-13+6 Weeks in a Population with Low and High Body Mass Index: a Prospective Study

PURPOSE

The earlier the detection and diagnosis of congenital heart diseases (CHD), the greater the clinical benefit; however, early fetal cardiac examination can be a challenge. The aim of our study is to demonstrate that the fetal cardiac examination at 13⁺⁰-13⁺⁶ weeks can be as adequately assessed as the examination performed at 16 weeks in patients with low and high body mass index (BMI).

METHODS

The study was a prospective observational cohort study. One hundred pregnant women at low risk of congenital heart anomalies were divided into two groups: 49 women with low BMI (<25) and 51 women with high BMI (≥ 25). A complete fetal cardiac scan was performed on each patient at 13⁺⁰-13⁺⁶ weeks, via the transvaginal and transabdominal approaches, and at 16 weeks by the transabdominal approach.

RESULTS

The examination at 13⁺⁰-13⁺⁶ weeks was adequately assessed in at least one of the two routes in 97 patients, as opposed to 87 patients at 16 weeks. A significantly higher adequate assessment rate was obtained at 13⁺⁰-13⁺⁶ weeks than at 16 weeks (p=0.017). The transvaginal approach showed the best resolution of the three examinations in 42% of women with BMI ≥35. No CHD were overlooked.

CONCLUSIONS

Early fetal echocardiography is feasible and accurate at 13⁺⁰-13⁺⁶ weeks. Within patients with high BMI, early fetal echocardiography may be performed two weeks in advance, since it allows visualization of the fetal heart through the transvaginal route with a higher resolution in a large number of women, which is not feasible at 16 weeks.

Efficacy of fetal cardiac axis evaluation in the first trimester as a screening tool for congenital heart defect or aneuploidy

Objective

To prove the efficacy of determining the abnormal fetal cardiac axis for screening congenital heart defects (CHDs) and predicting fetal aneuploidy at 11.0 to 13.6 weeks of pregnancy.

Methods

This retrospective study was performed at a single high-risk pregnancy center. The fetal cardiac axis was evaluated between 11.0 and 13.6 weeks of gestation in 142 fetuses. The cardiac axis in a 4-chamber view was measured as the angle between the line tracing the long axis of the heart and the line bisecting the thorax in the anteroposterior direction. A CHD was confirmed based on the second- to third-trimester fetal status or postnatal imaging. Aneuploidy was diagnosed using chorionic villus sampling, amniocentesis, or genetic testing after birth. Fisher's exact test was performed to assess the association between the fetal cardiac axis and the abnormal fetal status. A 2-way contingence table analysis was performed to confirm the efficacy of the fetal cardiac axis as a screening tool.

Results

Among the 142 fetuses, 10 had a CHD while 17 had aneuploidy. The abnormal fetal cardiac axis was significantly associated with CHDs (P=0.013) and aneuploidy (P=0.010). None of the fetuses with CHDs or aneuploidy had an isolated abnormal cardiac axis alone without other sonographic findings. The sensitivity of the fetal cardiac axis was 50.0% for CHDs and 41.2% for aneuploidy.

Conclusion

The fetal cardiac axis can be an additional helpful tool for prenatal screening of CHDs and aneuploidy in the first trimester.

4D fetal echocardiography-An update

With the introduction of the electronic 4-dimensional and spatial-temporal image Correlation (e-STIC), it is now possible to obtain large volume datasets of the fetal heart that are virtually free of artifact. This allows the examiner to use a number of imaging modalities when recording the volumes that include two-dimensional real time, power and color Doppler, and B-flow images. Once the volumes are obtained, manipulation of the volume dataset allows the examiner to recreate views of the fetal heart that enable examination of cardiac anatomy. The value of this technology is that a volume of the fetal heart can be obtained, irrespective of the position of the fetus in utero, and manipulated to render images for interpretation and diagnosis. This article presents a summary of the various imaging techniques and provides clinical examples of its application used for prenatal diagnosis of congenital heart defects and abnormal cardiac function.

Factors affecting the feasibility of routine first-trimester fetal echocardiography

OBJECTIVES

The purpose of our study was to assess the factors that may improve the feasibility of routine fetal echocardiography at the time of the first-trimester scan.

METHODS

In this prospective study, we included 616 healthy singleton fetuses. Examinations were performed transabdominally by a single sonographer at the beginning of his training in first-trimester screening. The fetal heart was examined by high-definition color Doppler imaging to obtain the 4-chamber view, right and left ventricular outflow tracts, and 3-vessel and trachea view. Logistic regression was used to investigate the effect on the ability to visualize different cardiac structures.

RESULTS

The frequency of successful heart examinations increased significantly with the number of scans performed (P < .05). The sonographer needed 180 examinations before he could successfully examine the heart in at least 80% of cases. Significant factors that increased the probability of adequate echocardiography were the length of the heart examination and the experience of the sonographer (P< .05) but not transducer-heart distance, maternal body mass index, fetal crown-rump length, placenta interposition, or restrictive fetal position. Visualization of the left ventricular outflow tract could be improved by increasing the experience of the sonographer and decreasing the transducer-heart distance. Also, visualization of the 3-vessel and trachea view depended on the length of the heart examination, the experience of the sonographer, an anterior position of the placenta, and a restrictive fetal position.

CONCLUSIONS

Competence in color flow mapping assessment of the fetal heart at gestational ages of 11 weeks to 13 weeks 6 days is achieved only after extensive supervised training.

Collaborative study of 4-dimensional fetal echocardiography in the first trimester of pregnancy

OBJECTIVES

Accumulating evidence supports a role for 2-dimensional fetal echocardiography in the first trimester of pregnancy for the identification of congenital heart defects. Our objective was to investigate the role of 4-dimensional (4D) sonography in the identification of congenital heart defects between 11 and 15 weeks of pregnancy.

METHODS

This study included 4 centers with expertise in first-trimester 4D fetal echocardiography. Fetuses with and without confirmed heart defects were evaluated between 11 and 15 weeks and their volume data sets were uploaded onto a centralized file transfer protocol server.

RESULTS

Forty-eight volume data sets from fetuses with normal (n = 17) and abnormal (n = 16) hearts were evaluated. Overall, the median (range) accuracy, sensitivity, and specificity, as well as the positive and negative likelihood ratios, for the identification of fetuses with congenital heart defects were 79% (77%-83%), 90% (70%-96%), 59% (58%-93%), 2.35 (2.05-9.80), and 0.18 (0.08-0.32), respectively.

CONCLUSIONS

(1) Four-dimensional fetal echocardiography can be performed in the first and early second trimesters of pregnancy; and (2) 4D volume data sets obtained from fetuses between 11 and 15 weeks can be remotely acquired and accurately interpreted by different centers.

Echocardiography in Early Pregnancy

Within the last decade, two significant events have contributed to the increasing interest in early fetal echocardiography. First, the introduction of high frequency vaginal ultrasound probes allows detailed visualization of cardiac structures at early stage of gestation, making early detection of fetal malformations possible. Second, the close relationship observed between some first trimester sonographic and Doppler markers and congenital heart defects allows an early identification of a high-risk group at 11 to 14 weeks of gestation. In this context, from the early 1990s, many authors have examined the potential role of the transvaginal approach to obtain earlier diagnosis of fetal cardiac malformations. Further studies have appeared in the literature showing that early transvaginal echocardiography in experienced hand is a fairly sensitive investigative tool. Although some malformations are detected as early as 11 weeks’ gestation, the optimal gestational age to perform the early scan is at least 13 weeks’ gestation. Transvaginal ultrasound is the preferred approach, although most of the authors agree that results can be improved if transabdominal ultrasound is also incorporated. The further application of color Doppler enhances visualization. The sensitivity and specificity of early fetal echocardiography for the detection of heart anomalies is acceptable compared to the ones obtained by mid-gestational echocardiography, showing a slight reduction in detection rates and an increase in false positive and negative rates. The cardiac anomalies detected at this early stage of pregnancy are mainly defects involving the four-chamber view, indicating that defects solely affecting the outflow tracts are difficult to diagnose in the first trimester of pregnancy. Heart defects diagnosed early in pregnancy tend to be more complex than those detected later, with a higher incidence of associated structural malformations, chromosomal abnormalities and spontaneous abortions. The neonate follow-up or postmortem examination in case of termination of pregnancy (TOP) is essential to assess the actual role of early fetal echocardiography. At present, early fetal echocardiography is a promising technique, which can be of considerable value for patients at high-risk. This technique is, however, currently limited to a few specialized centers.

The aim of this review is to explore the possibilities of examining the fetal heart at this early stage of pregnancy. This article also present our experience in the first multicenter trial in early fetal echocardiography performed in Spain. In accordance with other studies, this experience stresses the usefulness of early echocardiography when performed by expert operators on fetus specifically at risk for cardiac defects. Our review of these additional 48 cases contributes to the expanding literature on the ability of transvaginal ultrasonography to detect fetal heart defects in early pregnancy.

How to cite this article

Gabriel CC, Rodriguez PP. Echocardiography in Early Pregnancy. Donald School J Ultrasound Obstet Gynecol 2013;7(2):168-181.

Learning curve and factors influencing the feasibility of performing fetal echocardiography at the time of the first-trimester scan

The purpose of this study was to assess the learning curve and factors influencing the feasibility of performing a complete fetal cardiac examination at the time of the first-trimester scan. The study included 103 fetuses undergoing first-trimester scans. The maternal body mass index, fetal crown-rump length, and 8 cardiac parameters were evaluated: 4-chamber view, tricuspid regurgitation, outflow tract crossover, bifurcating pulmonary artery, 3-vessel view, aortic arch, superior and inferior venae cavae on sagittal views, and Doppler images of the ductus venosus. All examinations were performed transabdominally by a single sonologist. The average times from the first to last cardiac images obtained were calculated. A complete examination was feasible in 55% of the cases: 15% of the first 52 and 94% of the last 51. Of the 8 cardiac parameters, 59.5% were seen in cases 1 to 21, 75.0% in cases 22 to 52, and 98.6% in the last 51 cases (P = .0001). The average times spent on the examinations increased from 4.37 to 9.3 minutes among the 3 groups (P = .032). There was no statistically significant influence for the crown-rump length (P = .899) or body mass index (P = .752). This study indicates that a fetal cardiac examination is feasible in the first trimester. Sonographer experience and the examination duration seem to be the most influential factors affecting the completeness of the examination.

Role of first-trimester sonography in the diagnosis of aneuploidy and structural fetal anomalies

OBJECTIVE

We sought to determine the sensitivity of the first-trimester scan in the early diagnosis of aneuploidy and structural fetal anomalies in an unselected low-risk population.

METHODS

This was a retrospective chart review of all patients having first-trimester scans between 2002 and 2009. At our center, a survey of fetal anatomy is performed at the time of nuchal translucency assessment at 11 weeks to 13 weeks 6 days. A second-trimester scan is done at 20 to 23 weeks and a third-trimester scan at 32 to 35 weeks. Isolated sonographic findings of choroid plexus cysts and echogenic intracardiac foci were excluded. Lethal anomalies and those requiring immediate surgical intervention at birth were considered major structural anomalies. All scans were performed by a single sonologist certified by the Fetal Medicine Foundation. All neonates were examined at birth by a pediatrician.

RESULTS

Our study included 1370 fetuses. Six cases of aneuploidy (0.4%) were detected. The first-trimester scan detected 5 of 6 cases of aneuploidy (83%), confirmed by karyotype. There were 36 cases of structural fetal anomalies (2.6%); 20 (1.5%) were major anomalies. The first-trimester scan detected 16 of 36 (44%); 20 (56%) were identified by second- or third-trimester scans. The first-trimester scan detection rate for major structural anomalies was 14 of 20 (70%). The 5 that were missed by the first-trimester scan were detected by a second-trimester scan.

CONCLUSIONS

Our study emphasizes the importance of the first-trimester scan in the early detection of aneuploidy and structural fetal anomalies. In this small unselected low-risk population, the first-trimester scan detected 83% of aneuploidies and 70% of major structural anomalies. Our results are comparable to previously published studies from other centers and further exemplify the invaluable role of the first-trimester scan in the early detection of aneuploidy and structural anomalies in an unselected low-risk population.

Role of ultrasonography in early gestation in the diagnosis of congenital heart defects

OBJECTIVE

The purpose of this series was to determine the sensitivity of ultrasonography in early gestation (UEG) using nuchal translucency (NT) and the 4-chamber view (4CV) in the early diagnosis of congenital heart defects (CHDs).

METHODS

This was a retrospective chart review of all patients presenting for UEG between 2002 and 2009. At our center, a survey of fetal anatomy is performed at the time of the NT assessment at 11 weeks to 13 weeks 6 days. A second-trimester scan (STS) is done at 20 to 23 weeks and a third-trimester scan at 32 to 35 weeks. Suspected cases of CHDs were evaluated by a pediatric cardiologist. All neonates were examined at birth by a pediatrician, and when clinically indicated, fetal echocardiography was performed.

RESULTS

A total of 1370 fetuses were scanned. Congenital heart defects were identified in 8 (0.6%). Nuchal translucency was above the 95th percentile for gestational age (GA) in 6 of 8, and the 4CV was abnormal in 6 of 8. Ultrasonography in early gestation detected 75% fetuses with CHDs, and 25% were detected by an STS.

CONCLUSIONS

Our study emphasizes the importance of UEG in the detection of CHDs. In this small unselected low-risk population, UEG detected 75% of CHDs. Nuchal translucency was above the 95th percentile for GA, the 4CV was abnormal, or both in all 8 cases with CHDs.

Fetal echocardiography at 11 + 0 to 13 + 6 weeks using four-dimensional spatiotemporal image correlation telemedicine via an Internet link: a pilot study

OBJECTIVES

To assess whether spatiotemporal image correlation (STIC) volumes from fetuses at 11 + 0 to 13 + 6 weeks' gestation can be obtained by a non-expert and whether fetal echocardiography can be performed via a telemedicine link, providing a remote and reproducible diagnosis of the fetal heart condition.

METHODS

STIC volume datasets from 35 fetuses at 11 + 0 to 13 + 6 weeks were obtained prospectively by a general obstetrician, transmitted via the Internet and subsequently analyzed systematically by two different reviewers. Forty-nine pregnancies were initially enrolled into the study, but adequate volumes were not obtained for 14. Thirty-four datasets were obtained on transabdominal and one on transvaginal ultrasound examination. A checklist was used that included 18 structures and views relating to the fetal heart evaluation, and each reviewer assigned the variables as normal, abnormal or unsure. Cohen's kappa analysis was used to evaluate the agreement between reviewers and the reported findings were compared with the outcome where available.

RESULTS

The mean gestational age was 12 + 3 weeks and the mean (range) crown-rump length was 68 (47-84) mm. The mean maternal age was 33 (range, 26-41) years; 12/35 (34%) were older than 35 years. The four-chamber view obtained was apical in 22/35 (63%) cases and lateral in 13 (37%). Volume datasets were obtained after 12 weeks' gestation in 30/35 fetuses. Three cases had nuchal translucency thickness above the 99(th) percentile, and two of these had an abnormal heart. Five cases had abnormal outcomes. A mean of 3 (range, 1-6) STIC datasets per patient were acquired. The kappa index obtained confirmed interobserver reliability, with good or very good concordance (kappa > 0.6) in 14/18 structures and views related to the heart.

CONCLUSIONS

STIC volumes acquired between 11 + 0 and 13 + 6 weeks' gestation could be sent over the Internet and their analysis enabled recognition of most of the structures and views necessary to assess the small fetal cardiac anatomy, with a high degree of interobserver concordance.

Early fetal echocardiography--a reliable prenatal diagnosis tool

OBJECTIVE

This study was undertaken to evaluate the feasibility and to report the detection rate of cardiac anomalies with fetal echocardiography before 16 weeks' gestation.

STUDY DESIGN

This is a retrospective and prospective study of 160 early fetal echocardiograms. The mean gestational age was 13.5 weeks' gestation (range 11-15+6). All women had a repeat echocardiogram at 18 weeks' gestation and pregnancy outcome was obtained.

RESULTS

In all cases, a cardiac 4-chamber view was obtained. The atrioventricular valves were accurately seen in 154 (96%) cases; the ascending aorta and main pulmonary artery were visualized in 152 cases (95%). Overall, a satisfactory cardiac examination was feasible in 152 of cases (95%). There were 20 cardiac defects in this cohort (12.5%), 14 showed abnormalities at the time of the early ultrasound, whereas 6 were reported as normal. The sensitivity of early fetal echocardiography in this high-risk population was 70%, specificity 98%, positive predictive value 87.5%, and negative predictive value 96%.

CONCLUSION

The fetal heart can be examined early in pregnancy and a significant proportion of major cardiac defects identified.

Qualified and trained sonographers in the US can perform early fetal anatomy scans between 11 and 14 weeks

OBJECTIVES

The objective of this study was to determine the extent to which normal fetal anatomy can be detected between 11- and 14-week scan by sonographers in the US.

STUDY DESIGN

In a prospective cross-sectional study, 223 unselected women underwent a detailed assessment of fetal anatomy at 11 to 13 and 6/7 weeks by sonographers with transabdominal and/or transvaginal transducers. Thirty-seven structures were examined. Two groups were identified: group I: 121 patients between 11 and 12 weeks, and group II: 102 patients between 13 and 14 weeks.

RESULTS

Structures other than the posterior fossa, heart, genitalia, and the sacral spine were seen between 64% to 99% for group I, and 72% to 98% for group II. The following structures were detected with statistically significantly higher rates in group II compared with group I: cerebellum, posterior fossa, face, 4-chamber view left ventricular outflow tract, aortic arch, ductal arch, kidneys, and genitalia. Comparing the patients of group I and group II, the transvaginal scans yielded a higher detection rate of structures than do the transabdominal scans.

CONCLUSION

Anatomic surveys between 11 and 14 weeks can be performed by sonographers with good detection rates of most structures. Using the vaginal probe compared with the abdominal probe improved the detection rate at 13 to 14 weeks as well as 11 to 12 weeks. If early fetal structure evaluation is to become customary in the US, the present practice of experienced and trained sonographers to scan such patients can be maintained.

The role of fetal echocardiography in genetic sonography

Genetic sonography identifies between 60% and 93% of fetuses with trisomy 21. One of the reasons for the variation in sensitivity is because of the under-detection of congenital heart defects. Although congenital heart defects are present in 56% of second trimester fetuses and 44% of newborns with trisomy 21, most studies evaluating second-trimester fetuses at risk for trisomy 21 detect less than 10% of heart malformations. This review discusses an approach that allows the fetal sonographer to incorporate fetal echocardiography, based upon the examiner's level of skill and experience, when evaluating the fetus at risk for trisomy 21. The cardiovascular examination consists of three levels. In the Level I examination only noncardiac markers are evaluated for a detection rate of 60% and false-positive rate of 5.9%. The Level II examination incorporates the four-chamber view with non-cardiac markers. If the examiner can identify atrial and/or ventricular chamber disproportion, then the sensitivity is increased to 75%, with a false-positive rate of 6.4%. The Level III examination utilizes grayscale and color Doppler ultrasound to evaluate the fetal heart. If the examiner can identify ventricular septal defects, atrioventricular septal defects, pericardial effusion, tricuspid regurgitation, and chamber disproportion, then the sensitivity of genetic sonography increases to 91% with a false-positive rate of 14%. This review includes Likelihood Ratios for each of the ultrasound markers so that the examiner can compute the risk for trisomy 21 for an individual patient.