First-trimester fetal heart evaluation: time to move forward

Simplified First-Trimester Fetal Cardiac Screening Protocol for Low-Risk Pregnancies: Enhancing Efficiency and Accuracy

Introduction

Congenital heart defects (CHDs) are among the most prevalent congenital anomalies and are frequently detected in pregnancies classified as low-risk, rather than in high-risk groups. Advancements in ultrasound technology have heightened the emphasis on first-trimester fetal cardiac screening. However, due to the small size of the fetal heart at this stage, significant challenges persist, underscoring the need for simplified and reproducible protocols that can be effectively applied on a population-wide scale.

Methods

This paper describes a screening approach centred on the four-chamber view (4CV) and three-vessel tracheal view (3VTV) with colour Doppler imaging. This includes optimisation of ultrasound machine settings and the use of transabdominal and transvaginal approaches to enhance visualisation.

Results

Evidence demonstrates a CHD detection rate of 76% in low-risk populations, with a 95% success rate in obtaining the necessary views.

Discussion and Conclusion

Operator expertise and familiarity with cardiac anomalies are critical for accurate detection. The early identification of CHDs enables informed decision-making regarding pregnancy management. A simplified protocol for first-trimester cardiac screening offers a promising tool for the early identification of CHDs, enabling timely referral and intervention. To optimise detection rates and clinical outcomes, continuous professional education and systematic auditing processes are indispensable for practitioners performing early fetal cardiac screening.

Evaluation of first-trimester ultrasound screening strategy for fetal congenital heart disease

OBJECTIVE

To assess the performance of a standardized first-trimester ultrasound screening strategy for fetal congenital heart disease (CHD).

METHODS

This was a large retrospective study involving 74 839 consecutive mixed-risk pregnancies (77 396 fetuses). Routine ultrasound scans at 11 + 0 to 13 + 6 weeks' gestation were performed in a single center from January 2015 to June 2023. All fetuses were examined using a predefined standardized ultrasound scanning strategy with adjustment of imaging parameters, which included assessment of the fetal heart. The ultrasound results (e.g. extracardiac congenital malformations), ultrasound markers (e.g. nuchal translucency thickening, reversed a-wave in the ductus venosus and tricuspid regurgitation), follow-up, genetic tests and diagnostic results were recorded and analyzed.

RESULTS

In total, there were 831 cases of CHD, with an incidence of 1.07% (831/77 396). In the first-trimester scan, 590 fetuses were diagnosed with CHD, but four were confirmed as normal in later examinations. In addition, 245 cases were missed. The detection rate was 70.52%, with a sensitivity, specificity, false-positive rate and false-negative rate of 70.52%, 99.99%, 0.01% and 29.48%, respectively. In fetuses with negative ultrasound markers and no extracardiac malformations, the detection rate of CHD was 45.79% (185/404). There were 281 cases that underwent karyotyping and chromosomal microarray (245 fetuses) or whole-exome sequencing (36 fetuses). In total, 38.79% (109/281) had a positive genetic test result. There were 273/831 CHD cases associated with extracardiac malformations. The abnormal image patterns and abnormal features of each view in the scanning strategy were summarized.

CONCLUSIONS

Ultrasound screening for fetal CHD in the first trimester of pregnancy enables earlier prenatal diagnosis and consultation. The standardized ultrasound screening strategy used in this study had a high detection rate for fetal CHD in the first trimester. Our proposed fetal heart screening strategy shows promising effectiveness for early diagnosis of CHD and we recommend its use. It is important to note, however, that first-trimester ultrasound screening for fetal CHD should not replace fetal echocardiography in the second trimester. © 2025 International Society of Ultrasound in Obstetrics and Gynecology.

Second trimester echocardiography

Fetal echocardiography involves a comprehensive cardiac assessment aiming to make a complete structural examination of the heart as well as to detect signs of cardiovascular adaptation to different insults. For the former, this assessment entails expert's evaluation of the anatomy of the heart including additional views beyond the five axial views used in cardiac screening examinations and always complemented with colour and pulsed Doppler. Echocardiography may accurately diagnose most congenital heart defects in fetal life, which enables adjusting the perinatal management. For the latter, echocardiography encompasses cardiac morphometric assessment to identify signs of cardiac remodeling indicative of cardiac adaptation in structure, shape, and size in response to underlying diseases, and cardiac functional assessment to detect signs of systolic and/or diastolic dysfunction. The most used parameters to study the systolic function (stroke volume, cardiac output, ejection fraction, fractional shortening, and mitral and tricuspid annular plane systolic excursion), diastolic function (characteristics of flow in the precordial veins and through the atrioventricular valves) and global myocardial function (myocardial performance index) will be discussed in this review.

False-Positive Diagnosis of Congenital Heart Defects at First-Trimester Ultrasound: An Italian Multicentric Study

Objective. Our objective was to assess the proportion of false-positive CHD cases at the first-trimester evaluation of the fetal heart, performed by experienced operators. Methods. This multicenter retrospective study included of pregnant women with suspicion of CHDs during first-trimester screening for aneuploidies. In all cases, the fetal heart assessments were performed by obstetricians with extensive experience in first-trimester scanning, following an extended protocol proposed by SIEOG national guidelines, which included an axial view of the fetal abdomen and chest to assess visceral situs and evaluation of the four-chamber view (4CV) and three-vessel trachea view (3VTV) with color Doppler. In all suspected cases, fetal echocardiography was offered within 16 and/or at 19-22 weeks' gestation. Results. From a population of 4300 fetuses, 46 CHDs were suspected. Twenty-four cases were excluded from this analysis because the parents opted for early termination of the pregnancies due to associated structural and/or genetic anomalies. For the remaining 22, echocardiography was performed by 16 weeks in 14 cases (64%) and after 16 weeks in 8 cases. In 19 cases (86.4%), a fetal cardiologist confirmed the presence of a CHD. In three cases (13%), the cardiac anatomy was found to be normal at the fetal echocardiography and postnatally. Conclusions. This study shows that the proportion of false-positive cases at the first-trimester ultrasound examination of the fetal heart, performed by experienced operators, may carry a higher risk of false-positive diagnosis than expected. Therefore, this issue must be discussed in instances where a CHD is suspected at the first-trimester screening.

Slow flow HD and traditional CDFI technologies in identifying pulmonary veins in the first trimester

OBJECTIVE

This study aims to assess the feasibility and effectiveness of color doppler flow imaging (CDFI) technology and the Slow Flow HD imaging technique in identifying fetal pulmonary veins (PVs) in the first trimester (11-13 + 6 weeks), and further explore the factors affecting fetal pulmonary vein identification in early pregnancy.

METHODS

Echocardiography and scanning of PVs were performed in 240 normal singleton fetuses in early pregnancy by using CDFI and slow flow HD techniques, to compare the ability of two methods to identify the PVs. Slow Flow HD technology was used to further investigate the difference of PVs identification at different gestational ages [group I (11-11 + 6 weeks), group II (12-12 + 6 weeks), group III (13-13 + 6 weeks)] and with different maternal body mass indices (BMI) (≥ 25 and < 25). In 31 cases of 240 fetuses, transvaginal ultrasonography was added due to maternal habitus or significant retroversion of the uterus, and the difference in PVs identification between transabdominal and transvaginal examination was analyzed.

RESULTS

Successful PVs identification rates via CDFI and Slow Flow HD were 32.0% and 88.3%, respectively (p < 0.05). The identification rate of at least one and two pulmonary veins in Slow Flow HD was 88.3% and 76.2%, and all four pulmonary veins in 11.6% (p < 0.05). The identification rate of group I, II and III were 76.4%, 88.9% and 96.0%, respectively. The identification rate was 45.1% in the transabdominal ultrasound group and 83.8% in the transvaginal ultrasound group. The identification rate was 62.5% in the BMI ≥ 25 group and 94.7% in the BMI < 25 group (p < 0.05).

CONCLUSIONS

Slow Flow HD can detect PVs in early pregnancy more often than using CDFI. Slow Flow HD is a feasible and effective imaging technique for evaluating PVs in early pregnancy.

Four-section approach of fetal congenital heart disease at 11-13+6 weeks

Objective

The objective of the study is to explore the value of the four-section approach in detecting fetal heart defects in the first trimester (11-13+6 weeks), analyze the reasons for the inconsistency between the results of ultrasound examination in the first trimester and subsequent verification, and describe the most common abnormal flow patterns of four sections.

Materials and methods

Between June 2019 and June 2021, a prenatal four-section approach (upper abdominal transverse section, four-chamber section, three vessel-trachea section, and bilateral subclavian artery section) with verification results in early pregnancy was analyzed.

Results

In total, 9,533 fetuses were included. Finally, 176 fetuses with congenital heart disease (CHD), containing 34 types, were identified. The total detection rate of cardiac abnormalities was 1.85%. 102 cases were accurately diagnosed by ultrasonography during early pregnancy. A total of 74 fetuses who had inconsistent results between fetal cardiac ultrasound and verification in early pregnancy were reported, of which the cases of 22 fetuses were inconsistent due to disease evolution and progression and the cases of 52 fetuses were inconsistent due to missed diagnosis and misdiagnosis. The sensitivity, specificity, positive predictive value, and negative predictive value of the four-section approach were 67.05%, 99.96%, 96.58%, and 99.33%, respectively. In this study, a total of 30 abnormal ultrasonic imaging patterns in four sections were summarized.

Conclusion

We confirmed that the four-section approach in early pregnancy has a good diagnostic efficacy for fetal CHD. Intrauterine evolution of the fetal heart, missed diagnosis, and misdiagnosis are the reasons for the inconsistency between the results of early pregnancy ultrasound and subsequent verification. This study also presents the abnormal imaging patterns of four scan sections of CHD in early pregnancy, which are instructive for the rapid identification and diagnosis of CHD in the first trimester.

Accuracy of the Standardized Early Fetal Heart Assessment in Excluding Major Congenital Heart Defects in High-Risk Population: A Single-Center Experience

OBJECTIVE

To evaluate the ability of standardized early fetal heart assessment (EFHA) that includes the 4-chamber view, outflow tract relationship (OTR), and transverse arches views (TAV) of the great arteries in excluding major congenital heart defects (CHDs) in high-risk populations.

METHODS

This retrospective study included high-risk pregnancies for CHDs undergoing EFHA at 11-14 weeks of gestation. Risk factors for CHDs were diabetes mellitus, a family history of CHDs, a history of a CHD use of teratogenic medications, seizure disorder, assisted reproductive treatment-conceived pregnancy, presence of at least one of the ultrasound markers: enlarged nuchal translucency (>95th percentile), tricuspid regurgitation, and reversed a-wave in the ductus venosus, presence of an extracardiac or a suspected cardiac anomaly, a high-risk first trimester combined screen result, and multiple pregnancies. EFHA consisted of visualization of 4ChV, OTR, and TAV, with and without power Doppler ultrasound. The primary outcome was the negative predictive value of EFHA in excluding major CHDs.

RESULTS

EFHA was performed on 1055 fetuses. Of these, 1024 were used for the final analysis. Of these, 94.9% (n = 923) were singleton. The most common indication for EFHA was maternal DM (n = 231, 22.6%). The sensitivity, specificity, false positive, false negative, and accuracy of EFHA were 93.2%, 99.9%, 1.4%, 0.4%, and 99.5% (P < .0001), respectively, in entire included cases. The performance of EFHA was 88%, 99.9%, 1.4%, 0.4%, and 99.5% (P < .0001) respectively when the terminated cases were excluded.

CONCLUSION

Early fetal heart assessment is feasible for screening for major CHDs in high-risk populations. This approach may be expanded to the general obstetric population.