What to expect from routine midtrimester screening for congenital heart disease

Fetal intelligent navigation echocardiography (FINE) has superior performance compared to manual navigation of the fetal heart by non-expert sonologists

OBJECTIVES

Manual and intelligent navigation (i.e. fetal intelligent navigation echocardiography or FINE) by the operator are two methods to obtain standard fetal cardiac views from spatiotemporal image correlation (STIC) volumes. The objective was to compare the performance between manual and intelligent navigation (FINE) of the fetal heart by non-expert sonologists.

METHODS

In this prospective observational study, ten sonologists underwent formal training on both navigational methods. Subsequently, they were tested on their ability to obtain nine cardiac views from five STIC volumes of normal fetal hearts (19-28 gestational weeks) using such methods. The following parameters were determined for both methods: (1) success rate of obtaining nine cardiac views; (2) mean time to obtain nine cardiac views per sonologist; and (3) maximum number of cardiac views successfully obtained for each STIC volume.

RESULTS

All fetal cardiac images obtained from 100 STIC volumes (50 for each navigational method) were reviewed by an expert in fetal echocardiography. Compared to manual navigation, FINE was associated with a significantly: (1) higher success rate of obtaining eight (excluding the abdomen view) appropriate cardiac views (92-100% vs. 56-88%; all p<0.05); (2) shorter mean time (minute:seconds) to obtain nine cardiac views (2:11 ± 0:37 vs. 15:49 ± 7:44; p<0.0001); and (3) higher success rate of obtaining all nine cardiac views for a given STIC volume (86 vs. 14%; p<0.001).

CONCLUSIONS

When performed by non-expert sonologists, intelligent navigation (FINE) had a superior performance compared to manual navigation of the normal fetal heart. Specifically, FINE obtained appropriate fetal cardiac views in 92-100% of cases.

Treatment and care of women with epilepsy before, during, and after pregnancy: a practical guide

Women with epilepsy (WWE) wishing for a child represent a highly relevant subgroup of epilepsy patients. The treating epileptologist needs to delineate the epilepsy syndrome and choose the appropriate anti-seizure medication (ASM) considering the main goal of seizure freedom, teratogenic risks, changes in drug metabolism during pregnancy and postpartum, demanding for up-titration during and down-titration after pregnancy. Folic acid or vitamin K supplements and breastfeeding are also discussed in this review. Lamotrigine and levetiracetam have the lowest teratogenic potential. Data on teratogenic risks are also favorable for oxcarbazepine, whereas topiramate tends to have an unfavorable profile. Valproate needs special emphasis. It is most effective in generalized seizures but should be avoided whenever possible due to its teratogenic effects and the negative impact on neuropsychological development of in utero-exposed children. Valproate still has its justification in patients not achieving seizure freedom with other ASMs or if a woman decides to or cannot become pregnant for any reason. When valproate is the most appropriate treatment option, the patient and caregiver must be fully informed of the risks associated with its use during pregnancies. Folate supplementation is recommended to reduce the risk of major congenital malformations. However, there is insufficient information to address the optimal dose and it is unclear whether higher doses offer greater protection. There is currently no general recommendation for a peripartum vitamin K prophylaxis. During pregnancy most ASMs (e.g. lamotrigine, oxcarbazepine, and levetiracetam) need to be increased to compensate for the decline in serum levels; exceptions are valproate and carbamazepine. Postpartum, baseline levels are reached relatively fast, and down-titration is performed empirically. Many ASMs in monotherapy are (moderately) safe for breastfeeding and women should be encouraged to do so. This review provides a practically oriented overview of the complex management of WWE before, during, and after pregnancy.

Is Fetal Intelligent Navigation Echocardiography Helpful in Screening for d-Transposition of the Great Arteries?

OBJECTIVES

To evaluate the performance of fetal intelligent navigation echocardiography (FINE) applied to spatiotemporal image correlation (STIC) volumes in generating 3 specific abnormal cardiac views (left ventricular outflow tract, right ventricular outflow tract, and 3-vessel and trachea) used to screen for d-transposition of the great arteries (d-TGA).

METHODS

In this prospective study, 1 or more STIC volumes were obtained from the 4-chamber view in 34 second- and third-trimester fetuses with d-TGA. Each appropriate STIC volume was evaluated by STICLoop (Samsung Medison, Seoul, Korea) before applying the FINE method. One optimal volume per fetus was selected by observers. The visualization rates of the 3 specific abnormal cardiac views of d-TGA and their diagnostic elements were calculated, and the reliability between 2 observers was verified by the intraclass correlation coefficient.

RESULTS

Fetal intelligent navigation echocardiography applied to STIC volume data sets of fetuses with d-TGA successfully generated the 3 specific abnormal cardiac views in the following manner for 2 observers: 75.0% (n = 21) for the left ventricular outflow tract, 89.2% (n = 25) for the right ventricular outflow tract, and 85.7% (n = 24) for the 3-vessel and trachea view. Twenty-four (85.7%) of the STIC volume data sets showed 2 or 3 of the abnormal cardiac views. The interobserver intraclass correlation coefficients between the 2 observers ranged from 0.842 to 1.000 (95% confidence interval), indicating almost perfect reliability for the 2 observers.

CONCLUSIONS

In cases of d-TGA, the FINE method has a high success rate in generating 3 specific abnormal cardiac views and therefore can be performed to screen for this congenital defect.

Prospective evaluation of the fetal heart using Fetal Intelligent Navigation Echocardiography (FINE)

OBJECTIVE

To evaluate prospectively the performance of Fetal Intelligent Navigation Echocardiography (FINE) applied to spatiotemporal image correlation (STIC) volume datasets of the normal fetal heart.

METHODS

In all women between 19 and 30 weeks' gestation with a normal fetal heart, an attempt was made to acquire STIC volume datasets of the apical four-chamber view if the following criteria were met: (1) fetal spine located between 5- and 7-o'clock positions; (2) minimal or absent shadowing (including a clearly visible transverse aortic arch); (3) absence of fetal breathing, hiccups, or movement; and (4) adequate image quality. Each STIC volume successfully acquired was evaluated by STICLoop™ to determine its appropriateness before applying the FINE method. Visualization rates of fetal echocardiography views using diagnostic planes and/or Virtual Intelligent Sonographer Assistance (VIS-Assistance®) were calculated.

RESULTS

One or more STIC volumes (365 in total) were obtained successfully in 72.5% (150/207) of women undergoing ultrasound examination. Of the 365 volumes evaluated by STICLoop, 351 (96.2%) were considered to be appropriate. From the 351 STIC volumes, only one STIC volume per patient (n = 150) was analyzed using the FINE method, and consequently nine fetal echocardiography views were generated in 76-100% of cases using diagnostic planes only, in 98-100% of cases using VIS-Assistance only, and in 98-100% of cases when using a combination of diagnostic planes and/or VIS-Assistance.

CONCLUSIONS

In women between 19 and 30 weeks' gestation with a normal fetal heart undergoing prospective sonographic examination, STIC volumes can be obtained successfully in 72.5% of cases. The FINE method can be applied to generate nine standard fetal echocardiography views in 98-100% of these cases using a combination of diagnostic planes and/or VIS-Assistance. This suggests that FINE could be implemented in fetal cardiac screening programs. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Fetal Intelligent Navigation Echocardiography (FINE): a novel method for rapid, simple, and automatic examination of the fetal heart

OBJECTIVE

To describe a novel method (Fetal Intelligent Navigation Echocardiography (FINE)) for visualization of standard fetal echocardiography views from volume datasets obtained with spatiotemporal image correlation (STIC) and application of 'intelligent navigation' technology.

METHODS

We developed a method to: 1) demonstrate nine cardiac diagnostic planes; and 2) spontaneously navigate the anatomy surrounding each of the nine cardiac diagnostic planes (Virtual Intelligent Sonographer Assistance (VIS-Assistance®)). The method consists of marking seven anatomical structures of the fetal heart. The following echocardiography views are then automatically generated: 1) four chamber; 2) five chamber; 3) left ventricular outflow tract; 4) short-axis view of great vessels/right ventricular outflow tract; 5) three vessels and trachea; 6) abdomen/stomach; 7) ductal arch; 8) aortic arch; and 9) superior and inferior vena cava. The FINE method was tested in a separate set of 50 STIC volumes of normal hearts (18.6-37.2 weeks of gestation), and visualization rates for fetal echocardiography views using diagnostic planes and/or VIS-Assistance® were calculated. To examine the feasibility of identifying abnormal cardiac anatomy, we tested the method in four cases with proven congenital heart defects (coarctation of aorta, tetralogy of Fallot, transposition of great vessels and pulmonary atresia with intact ventricular septum).

RESULTS

In normal cases, the FINE method was able to generate nine fetal echocardiography views using: 1) diagnostic planes in 78-100% of cases; 2) VIS-Assistance® in 98-100% of cases; and 3) a combination of diagnostic planes and/or VIS-Assistance® in 98-100% of cases. In all four abnormal cases, the FINE method demonstrated evidence of abnormal fetal cardiac anatomy.

CONCLUSIONS

The FINE method can be used to visualize nine standard fetal echocardiography views in normal hearts by applying 'intelligent navigation' technology to STIC volume datasets. This method can simplify examination of the fetal heart and reduce operator dependency. The observation of abnormal echocardiography views in the diagnostic planes and/or VIS-Assistance® should raise the index of suspicion for congenital heart disease.

The antenatal detection rate of major congenital heart disease in Scotland

Ultrasonography has been used to detect fetal congenital heart disease since the 1980s, although there has been little uniformity in policy. In the UK, data published for 1993-1995 found an average detection rate of 23.4% with a Scottish rate of 9.6%. At the time of this study, 10 out of the 14 health boards in Scotland were implementing the 16-22-week fetal anomaly scan (FAS). The aims of this study were to determine the rate of antenatal diagnosis of major congenital heart disease (MCHD) throughout Scotland during 1 January to 31 December 2006, to document the regional differences in detection and to determine if implementation of a FAS significantly improved rates. Retrospective data were collected from the centralized Paediatric Cardiac Services in Edinburgh and Glasgow. The database contains information on all infants with cardiac disease in Scotland. All infants requiring cardiac intervention or dying in the first year of life were included. The results showed that the antenatal diagnosis rate for Scotland was 28% (95% CI 21.2%, 34.9%). The Scottish health boards that had implemented the FAS had a significantly higher antenatal detection rate (χ2 test P = 0.037). In conclusion, antenatal detection rate of MCHD varies widely throughout Scotland. Implementation of the FAS has made a significant difference to antenatal diagnosis

Contemporary clinical applications of spatio-temporal image correlation in prenatal diagnosis

PURPOSE OF REVIEW

Four-dimensional fetal echocardiography has the potential to reduce the operator dependency of two-dimensional ultrasonography and increase the detection rate of congenital heart defects (CHDs). This review is intended to summarize recent evidence of the important role that four-dimensional ultrasonography with spatio-temporal image correlation (STIC) may play in the prenatal diagnosis of CHDs.

RECENT FINDINGS

Four-dimensional ultrasonography with STIC may provide the opportunity for telemedicine in the prenatal diagnosis of CHDs because four-dimensional volume datasets can be remotely acquired and accurately interpreted by different centers. Four-dimensional ultrasonography with STIC is an accurate and reproducible technique for the prenatal diagnosis of CHDs. Different four-dimensional rendering techniques can provide important insight into the spatial relationships of normal and abnormal fetal vascular structures.

SUMMARY

Four-dimensional fetal echocardiography with STIC may facilitate the examination of the fetal heart and could potentially increase the detection rate of CHDs.

Four-chamber view and 'swing technique' (FAST) echo: a novel and simple algorithm to visualize standard fetal echocardiographic planes

OBJECTIVE

To describe a novel and simple algorithm (four-chamber view and 'swing technique' (FAST) echo) for visualization of standard diagnostic planes of fetal echocardiography from dataset volumes obtained with spatiotemporal image correlation (STIC) and applying a new display technology (OmniView).

METHODS

We developed an algorithm to image standard fetal echocardiographic planes by drawing four dissecting lines through the longitudinal view of the ductal arch contained in a STIC volume dataset. Three of the lines are locked to provide simultaneous visualization of targeted planes, and the fourth line (unlocked) 'swings' through the ductal arch image (swing technique), providing an infinite number of cardiac planes in sequence. Each line generates the following plane(s): (a) Line 1: three-vessels and trachea view; (b) Line 2: five-chamber view and long-axis view of the aorta (obtained by rotation of the five-chamber view on the y-axis); (c) Line 3: four-chamber view; and (d) 'swing line': three-vessels and trachea view, five-chamber view and/or long-axis view of the aorta, four-chamber view and stomach. The algorithm was then tested in 50 normal hearts in fetuses at 15.3-40 weeks' gestation and visualization rates for cardiac diagnostic planes were calculated. To determine whether the algorithm could identify planes that departed from the normal images, we tested the algorithm in five cases with proven congenital heart defects.

RESULTS

In normal cases, the FAST echo algorithm (three locked lines and rotation of the five-chamber view on the y-axis) was able to generate the intended planes (longitudinal view of the ductal arch, pulmonary artery, three-vessels and trachea view, five-chamber view, long-axis view of the aorta, four-chamber view) individually in 100% of cases (except for the three-vessels and trachea view, which was seen in 98% (49/50)) and simultaneously in 98% (49/50). The swing technique was able to generate the three-vessels and trachea view, five-chamber view and/or long-axis view of the aorta, four-chamber view and stomach in 100% of normal cases. In the abnormal cases, the FAST echo algorithm demonstrated the cardiac defects and displayed views that deviated from what was expected from the examination of normal hearts. The swing technique was useful for demonstrating the specific diagnosis due to visualization of an infinite number of cardiac planes in sequence.

CONCLUSIONS

This novel and simple algorithm can be used to visualize standard fetal echocardiographic planes in normal fetal hearts. The FAST echo algorithm may simplify examination of the fetal heart and could reduce operator dependency. Using this algorithm, inability to obtain expected views or the appearance of abnormal views in the generated planes should raise the index of suspicion for congenital heart disease.

Impact and issues of detecting fetal congenital heart defects in Kyushu, Japan

AIM

To determine the current status of fetal CHD screening in our region and to establish a CHD screening system in Japan.

MATERIAL AND METHODS

Subjects were 168 fetuses prenatally-diagnosed with CHD at four referral centers in Japan from 2003 to 2007. Subjects were divided into two groups: group A (n = 84) included cases without extracardiac sonographic abnormalities and known risk factors for CHD and group B (n = 84) included those with extracardiac sonographic abnormalities or risk factors. The diagnostics and outcomes between the groups were analyzed.

RESULTS

There were more cases of single ventricle and restrictive ductus arteriosus and fewer cases of ventricular septal defect and double outlet right ventricle in group A than in group B (P < 0.05). In group A, the most frequent referral reason was an abnormal four-chamber view. In group B, 37 cases had chromosomal anomalies. The mortality rates in group B were higher than those in group A (P < 0.05). There were no differences in mortality rates between fetuses without chromosomal anomalies in group B and group A.

CONCLUSION

Prenatally-diagnosed CHD were mostly limited to those cases with obvious abnormalities in the four-chamber view or those with chromosomal anomalies. Prenatal detection of CHD is useful for the prediction of outcomes.

Collaborative study on 4-dimensional echocardiography for the diagnosis of fetal heart defects: the COFEHD study

OBJECTIVE

Congenital anomalies are the leading cause of infant mortality in the United States, and congenital heart defects (CHDs) are the most common type of birth defects. Recently, 4-dimensional ultrasonography (4DUS) with spatiotemporal image correlation (STIC) has been introduced for fetal echocardiography. Accumulating evidence indicates that 4DUS with STIC may facilitate the examination of the fetal heart. Our objectives were to determine the accuracy of 4DUS for the diagnosis of CHDs and the agreement among centers.

METHODS

This study included 7 centers with expertise in 4D fetal echocardiography. Fetuses with and without confirmed heart defects were scanned between 18 and 26 weeks, and their volume data sets were uploaded onto a centralized file transfer protocol server. Intercenter agreement was determined using a κ statistic for multiple raters.

RESULTS

Ninety volume data sets were randomly selected for blinded analysis. Overall, the median (range) sensitivity, specificity, positive and negative predictive values, and false-positive and -negative rates for the identification of fetuses with CHDs were 93% (77%-100%), 96% (84%-100%), 96% (83%-100%), 93% (79%-100%), 4.8% (2.7%-25%), and 6.8% (5%-22%), respectively. The most frequent CHDs were conotruncal anomalies (36%). There was excellent intercenter agreement (κ = 0.97).

CONCLUSIONS

(1) Four-dimensional volume data sets can be remotely acquired and accurately interpreted by different centers. (2) Among centers with technical expertise, 4DUS is an accurate and reliable method for fetal echocardiography.

Three- and 4-dimensional ultrasonography in the prenatal evaluation of fetal anomalies associated with trisomy 18

OBJECTIVE

The purpose of this study was to assess the usefulness of 3- and 4-dimensional ultrasonography (3D/4DUS) for the description of anomalies associated with trisomy 18 and to determine whether 3D/4DUS adds diagnostic information over what is provided by conventional 2-dimensional ultrasonography (2DUS) alone.

METHODS

Twenty-six fetuses subsequently proven to have trisomy 18 underwent prenatal ultrasonographic evaluations by both 2DUS and 3D/4DUS. Volume data sets were acquired by the same sonographers after the conventional 2DUS examinations and were explored with 4-dimensional imaging software by another independent examiner blinded to the indications of 2DUS. The findings detected by 2DUS and 3D/4DUS were compared with those acquired at autopsy. The sensitivity of each modality for detecting anomalies was calculated and compared by the McNemar test.

RESULTS

Excluding polyhydramnios, there were 131 anomalies confirmed postnatally in 26 fetuses with trisomy 18. There was a statistically significant difference in the sensitivity for detecting anomalies between 3D/4DUS and 2DUS (93.89% versus 73.28%; McNemar value = 23.31; P < .05), especially in anomalies of the face/neck (96.15% versus 65.38%; McNemar value = 6.13; P < .05) and extremities (96.3% versus 48.15%; McNemar value = 11.07; P < .05). Three- and 4-dimensional ultrasonography provided additional diagnostic information for 83.97% of the anomalies related to trisomy 18 and influenced the obstetric management of 4 fetuses.

CONCLUSIONS

Three- and 4-dimensional ultrasonography offered diagnostic advantages for many anomalies associated with trisomy 18, especially for anomalies of the extremities and face. This modality could be a powerful adjunct to 2DUS in the prenatal anatomic evaluation of fetuses with trisomy 18.

A systematic approach to the use of the multiplanar display in evaluation of abnormal vascular connections to the fetal heart using 4-dimensional ultrasonography

OBJECTIVE

The multiplanar display is a modality that allows the simultaneous visualization of 3 orthogonal planes from volume data sets obtained with 3- and 4-dimensional ultrasonography. Simultaneous display of standard views used in fetal echocardiography and their orthogonal planes may provide novel ultrasonographic views for examination of the fetal heart and its vascular connections. This study was designed to determine the clinical utility of the multiplanar display in the examination of abnormal vascular connections to the fetal heart.

METHODS

We reviewed 4-dimensional volume data sets, acquired with the spatiotemporal image correlation technique, from patients with abnormal vascular connections to the fetal heart. Multiplanar views of the fetal heart were used to simultaneously display standard planes used in fetal echocardiography and their corresponding orthogonal planes.

RESULTS

This study included 4 volume data sets from fetuses with confirmed abnormal vascular connections to the heart, including: (1) an interrupted inferior vena cava with azygos or hemiazygos vein continuation; (2) a persistent left superior vena cava draining into a dilated coronary sinus; and (3) a dilated superior vena cava associated with a thoracic lymphangioma. Simultaneous visualization of orthogonal planes displaying abnormal vascular connections to the fetal heart facilitated identification of the abnormal vessels and their spatial relationships with other vascular structures.

CONCLUSIONS

Multiplanar imaging can be used to assess abnormal vascular connections to the fetal heart and may provide novel ultrasonographic planes for fetal echocardiography using 3- and 4-dimensional ultrasonography.

The role of the sagittal view of the ductal arch in identification of fetuses with conotruncal anomalies using 4-dimensional ultrasonography

OBJECTIVE

Conotruncal anomalies represent one fifth of all congenital heart defects (CHDs) detected in the fetus. However, the spatial relationship of the great vessels is incorrectly defined in about 20% of these cases. The sagittal view of the ductal arch is considered a standard ultrasonographic view in fetal echocardiography and can be easily visualized using 4-dimensional (4D) ultrasonography. This study was designed to determine the role of this ultrasonographic plane for the prenatal diagnosis of conotruncal anomalies.

METHODS

We reviewed 4D volume data sets, acquired with the spatiotemporal image correlation technique, from fetuses with and without confirmed conotruncal anomalies. The visualization rate of the sagittal view of the ductal arch was compared among groups using standardized multiplanar views.

RESULTS

This study included 183 volume data sets from fetuses in the following groups: (1) normal echocardiographic findings (n = 130); (2) conotruncal anomalies (n = 18); and (3) other CHDs (n = 35). Volumes of poor image quality were excluded from analysis (8.2% [15/183]). The visualization rate of the sagittal view of the ductal arch was significantly lower in fetuses with conotruncal anomalies (5.6% [1/18]) than that in fetuses without abnormalities (93.1% [108/116]) and that in fetuses with other CHDs (79.4% [27/34]; P < .01). Absence of visualization of the sagittal view of the ductal arch was associated with a likelihood ratio of 9.44 (95% confidence interval, 5.8-15.5) to have conotruncal anomalies.

CONCLUSIONS

The sagittal view of the ductal arch may play an important role in the screening and prenatal diagnosis of conotruncal anomalies in 4D ultrasonography.

Prenatal screening for congenital heart disease with four-chamber and outflow-tract views: a multicenter study

OBJECTIVE

Congenital heart diseases (CHD) are the most common congenital anomalies, and most cases occur in the low-risk population. Prenatal ultrasound screening based on visualization of the four-chamber view has had disappointing results in detecting these anomalies thus far. The aim of this study was to evaluate the diagnostic accuracy of ultrasound screening based on the combination of the four-chamber and outflow-tract views.

METHODS

We conducted a multicenter prospective observational study in 15 obstetric units in the Piedmont Region, Italy. All operators received specific training. Data were recorded regarding visualization of the four-chamber view and the outflow tracts at each routine scan in pregnancies without any risk factor. When an anomaly was suspected, the patient was sent to the referral center. We obtained the follow-up data of the newborns until discharge from hospital and calculated the diagnostic accuracy of the test.

RESULTS

9074 ultrasound scans were performed on 7041 women and complete follow-up information was available for 6368 of them. Fifty-eight cases of CHD were observed at birth or postmortem (prevalence 9.1 per thousand); 38 of them were diagnosed in utero. The sensitivity of the test was 65.5%, the specificity 99.7%, the positive predictive value 70.4% and the negative predictive value 99.7%. The sensitivity of the four-chamber view alone was 60.3%.

CONCLUSIONS

The sensitivity was significantly higher than that in a similar study performed in 1997 in the same setting. This improvement can be attributed in part to extension of the examination to the outflow-tract view, but also to technological developments and better training of the operators.

A novel algorithm for comprehensive fetal echocardiography using 4-dimensional ultrasonography and tomographic imaging

OBJECTIVE

Tomographic ultrasound imaging (TUI) is a new display modality that allows simultaneous visualization of up to 8 parallel anatomic planes. This study was designed to determine the role of a novel algorithm combining spatiotemporal image correlation and TUI to visualize standard fetal echocardiographic planes.

METHODS

Volume data sets from fetuses with and without congenital heart defects (CHDs) were examined with a novel algorithm that allows simultaneous visualization of the 3-vessel and trachea view, the 4-chamber view, and outflow tracts. Visualization rates for these planes as well as the ductal arch and 5-chamber view were calculated.

RESULTS

(1) Two hundred twenty-seven volume data sets from fetuses without (n = 138) and with (n = 14) CHDs were reviewed; (2) among fetuses without CHDs, the 4-chamber view, 5-chamber view, ductal arch, 3-vessel and trachea view, left outflow tract, and short axis of the aorta were visualized in 99% (193/195), 96.9% (189/195), 98.5% (192/195), 88.2% (172/195), 93.3% (182/195), and 87.2% (170/195) of the volume data sets, respectively; (3) these views were visualized in 85% (17/20), 80% (16/20), 65% (13/20), 55% (11/20), 55% (11/20), and 70% (14/20) of the volume data sets, respectively, from fetuses with CHDs; and (4) simultaneous visualization of the short axis of the aorta, 3-vessel and trachea view, left outflow tract, and 4-chamber view was obtained in 78% (152/195) of the volume data sets from fetuses without CHDs and in 40% (8/20) of those with CHDs.

CONCLUSIONS

The 3-vessel and trachea view, the 4-chamber view, and both outflow tracts can be simultaneously visualized using a novel algorithm combining spatiotemporal image correlation and TUI.

The examiner's ultrasound experience has a significant impact on the detection rate of congenital heart defects at the second-trimester fetal examination

OBJECTIVES

To determine whether training and experience in performing ultrasound examinations are factors that influence the prenatal detection of congenital heart defects (CHDs) in a non-selected population, in order to evaluate and improve the current training program.

METHODS

All pregnant women who received a routine second-trimester ultrasound scan by a sonographer/midwife and delivered at our hospital between February 1991 and December 2001 were registered prospectively. Less experienced sonographer/midwives who had performed between 200 and 2000 routine examinations were compared with experienced sonographer/midwives who had carried out more than 2000 examinations. During the first 5 years of the study the heart structures obtained were registered in detail.

RESULTS

Of 29,035 fetuses, 35/82 (43%) major CHDs were prenatally detected at the routine examination. The experienced sonographer/midwives obtained both the four-chamber view and the great arteries in 75%; the figure for the less experienced sonographer/midwives was 36% (P < 0.001). The differences in detecting major heart defects were 22/42 (52%) and 13/40 (32.5%), isolated CHDs 8/18 (44%) and 6/22 (27%) and CHDs with associated malformations 14/24 (58%) and 7/18 (39%), respectively. In both groups some CHDs with an abnormal four-chamber view were missed, although the experienced sonographer/midwives recognized significantly more of the abnormal views than did the less experienced sonographer/midwives (P = 0.002).

CONCLUSIONS

Experience has a significant impact on the examination of the fetal heart and the prenatal detection rate of major CHDs. To avoid a relatively long learning curve, ultrasound education needs to intensify the teaching of the basic four-chamber view. The great arteries should be included after additional training. Those basic views of the fetal heart must be mastered before new views and advanced technology are added to the fetal heart examination.

Accuracy of fetal echocardiography in the routine detection of congenital heart disease among unselected and low risk populations: a systematic review

OBJECTIVE

To determine among unselected and low risk populations the accuracy with which fetal echocardiography during the second trimester detects congenital heart disease.

DESIGN

A systematic review of studies that assess the accuracy of fetal echocardiography.

SETTING

District General Hospital and Tertiary referral centres.

POPULATION

Women during the second trimester attending for ultrasound assessment.

METHODS

General bibliographic databases (e.g. MEDLINE, EMBASE) and specialist computerised databases (e.g. Cochrane Library, National Research Register), grey literature, manual searching of reference lists of primary and review articles and personal contact with experts were used to identify studies. Studies were included if fetal echocardiography among unselected or low risk pregnant women was compared against a postnatal reference standard. Data were extracted on quality, study design and characteristics, and accuracy data to construct 2 x 2 tables. Data were synthesised qualitatively, and sensitivity and specificity with 95% confidence intervals were calculated.

MAIN OUTCOME MEASURE

Sensitivity and specificity.

RESULTS

Five primary studies met the inclusion criteria and comprised 60,901 subjects. One study assessed the accuracy of fetal echocardiography among an unselected population and four studies among low risk populations. All eligible studies found that fetal echocardiography helped to correctly diagnose normal fetus among unselected and low risk populations. Correct diagnosis of babies for congenital heart defects was higher among the unselected population (85%) than among the low risk populations (range from 35% to 86%); however, the potential for ascertainment bias and the choice of reference standard limits the validity of this finding. The variation in sensitivity across studies was not explainable by clinical factors such as scanning regime, operator skill and equipment.

CONCLUSIONS

The evidence from this review about the accuracy of fetal echocardiography does not lend support to its routine use among unselected and low risk populations during the second trimester to detect congenital heart disease.

Routine fetal cardiac screening: what are we doing and what should we do?

In many countries, ultrasound examination is used in the second trimester to look for congenital malformations as part of routine prenatal care. While tertiary centres scanning high-risk pregnancies have reported a high degree of accuracy in the detection of congenital heart disease, many studies have shown that cardiac abnormalities are commonly overlooked during routine obstetric evaluation and there still remains a huge variation between centres. The majority of babies with congenital heart disease are born to mothers with no identifiable high-risk factors and so will not be detected unless there is widespread screening of the low-risk population. It is feasible to achieve widespread screening for fetal congenital heart disease in low-risk groups, but this does need commitment and effort from those performing the scans and those teaching them how to examine the heart. Staff performing routine obstetric ultrasound scans should learn a simple technique for examining the fetal heart and to use this in all patients. Links to a tertiary centre can provide support for checking scans of concern as well as for providing training and for obtaining feedback. In addition, an audit system needs to be established in each centre to trace false-positive and false-negative cases as well as to confirm true positives and true negatives.