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In patients without risk factors for congenital heart disease, full fetal echocardiography, which is generally more time‐consuming and expensive than general obstetric sonography, is not indicated unless cardiac anomalies are suspected. Many risk factors for congenital heart disease have been described (Table 6.1).

The four‐chamber view of the heart has been suggested as an easy way of screening for congenital heart disease, although its sensitivity to significant cardiac anomalies has varied in the literature. Approximately one‐third of cases of major heart disease are detected on screening prenatal ultrasound, according to a review of the world’s literature. Our own experience suggests that it has a very high positive predictive value, with about half of patients referred for abnormal four‐chamber views actually having cardiac anomalies. Current recommendations from US medical societies, including the American College of Obstetricians and Gynecologists (ACOG), the American Institute of Ultrasound in Medicine (AIUM), and the International Society of Ultrasound in Obstetrics and Gynecology, all call for including outflow tract views in the standard (or so‐called “Level 1”) obstetric scan.

Table 6.1 Indications for fetal echocardiography

Familial risk factors

History of congenital heart disease (CHD)

Previous sibling with CHD

Paternal CHD

Second‐degree relative to fetus with CHD

Mendelian syndromes that include congenital heart disease (e.g., Noonan, tuberous sclerosis)

Maternal risk factors

Congenital heart disease

Cardiac teratogen exposure:

Lithium carbonate

Phenytoin

Valproic acid

Trimethadione

Carbamazepine

Isotretinoin

Paroxetine

Maternal metabolic disorders:

Diabetes mellitus

Phenylketonuria

In vitro fertilization

Fetal risk factors

Suspected cardiac anomaly

Extracardiac anomalies

Chromosomal

Anatomical

Fetal cardiac arrhythmia

Irregular rhythm

Tachycardia (greater than 200 bpm) in absence of chorioamnionitis

Fixed bradycardia

Nonimmune hydrops fetalis

Lack of reassuring four‐chamber view during basic obstetric scan

Monochorionic twins

Increased nuchal translucency space at 11–14 weeks of gestation

Full fetal echocardiography includes obtaining all the views in the fetus routinely obtained in postnatal echocardiography (Table 6.2) using both real‐time gray‐scale and color Doppler imaging. Additionally, spectral Doppler, cardiac biometry, and M‐mode data can be obtained as indicated. Fetal echocardiographers use these latter techniques variably. The two‐dimensional examination should be sufficient to exclude significant heart disease in the vast majority of affected individuals. The more sophisticated studies are especially useful in cases of suspected structural or functional abnormalities.

In a recent Practice Parameter, the AIUM has described required and optional components of the detailed fetal echocardiographic examination, shown in Table 6.3.

Table 6.2 Standard fetal echocardiographic views and what to see

Four chamber

Situs: check fetal position and stomach

Axis of heart to the left

Intact interventricular septum

Atria approximately equal sizes

Ventricles approximately equal sizes

Free movement of mitral and tricuspid valves

Heart occupies about one‐third of chest area

Foramen ovale flap (atrial septum primum) visible in left atrium

Long‐axis left ventricle

Intact interventricular septum

Continuity of the ascending aorta with mitral valve posteriorly

Interventricular septum anteriorly

Short axis of great vessels

Vessel exiting the anterior (right) ventricle bifurcates, confirming it is the pulmonary artery

Aortic arch

Vessel exiting the posterior (left) ventricle arches and has three head vessels, confirming it is the aorta

Pulmonary artery–ductus arteriosus

Continuity of the ductus arteriosus with the descending aorta

Venous connections

Superior and inferior vena cavae enter right atrium

Pulmonary veins entering left atrium from both right and left lungs

Table 6.3 AIUM recommended components of detailed fetal echocardiographic exam

Gray‐scale imaging Four‐chamber view including pulmonary veinsLeft ventricular outflow tractRight ventricular outflow tractBranch pulmonary artery bifurcationThree‐vessel view (including view with PA bifurcation and more superior view with ductal arch)Short‐axis views (“low” for ventricles, “high” for outflow tracts)Long‐axis view (if clinically relevant)Aortic archDuctal archSuperior (SVC) and inferior vena cava (IVC) Color Doppler sonography Systemic veins (including superior and inferior vena cava and ductus venosus)Pulmonary veins (at least two, one right vein and one left vein)Atrial septum and foramen ovaleAtrioventricular valvesVentricular septumSemilunar valvesDuctal archAortic arch Pulsed Doppler sonography Right and left atrioventricular valvesRight and left semilunar valvesPulmonary veins (at least two; one right vein and one left vein)Ductus venosusSuspected structural or flow abnormality on color Doppler sonography Heart rate and rhythm assessmentCardiac biometry (z‐scores recommended) Aortic and pulmonary valve annulus in systole (absolute size with comparison of left‐ to right‐sided valves)Tricuspid and mitral valve annulus in diastole (absolute size with comparison of left‐ to right‐sided valves) Optional biometry Right and left ventricular lengthsAortic arch and isthmus diameter measurements from the sagittal arch view or three vessels and trachea view with comparison of aortic isthmus to ductus arteriosusMain pulmonary artery and ductus arteriosus measurementsEnd‐diastolic ventricular diameter just inferior to the atrioventricular valve leaflets in the short or long axis viewThickness of the ventricular free walls and interventricular septum in diastole just inferior to the atrioventricular valvesAdditional measurements if clinically relevant, including:systolic ventricular dimensions (short or long axis views)transverse atrial dimensionsbranch pulmonary artery diametersCardiac function assessment (if clinically relevant) Fractional shorteningVentricular strainMyocardial performance index