Is fetal echocardiogram safe during pregnancy?

What does the evidence say about fetal echocardiogram during pregnancy?

1. A fetal echocardiogram is an ultrasound study of fetal cardiac structure, rhythm, function, and blood flow. MedlinePlus says it is usually performed at about 18 to 24 weeks and has no known risk to the pregnant patient or fetus. 1
2. Common referral reasons include a possible heart finding or rhythm difference on routine ultrasound, a close family history of congenital heart disease, pregestational diabetes, lupus, phenylketonuria, first-trimester rubella, selected medicine exposures, or a chromosome finding. 1
3. A detailed review of prenatal cardiac imaging identifies 18 to 22 weeks as the usual window and distinguishes fetal echocardiography from the cardiac views included in every routine anatomy scan. Earlier examination is generally reserved for pregnancies at highest risk. 2
4. SMFM suggests offering fetal echocardiography for pregnancies achieved with IVF and intracytoplasmic sperm injection, while grading the recommendation 2C. This is separate from its stronger recommendation for a detailed obstetric ultrasound in those pregnancies. 3
5. Fetal echocardiography has limits even in expert practice. In a single-center series of 222 fetuses with prenatally identified major heart disease, 13.5 percent had a discrepancy with postnatal findings, most minor or moderate, and technical limitations were the leading contributing factor. 4

Is fetal echocardiogram safe in each trimester?

• First trimester. An early fetal echocardiogram may be considered for a very high-risk pregnancy, but small structures and early development limit what can be seen. An early study often needs a repeat detailed examination in the usual second-trimester window.
• Second trimester. Most fetal echocardiograms are performed around 18 to 24 weeks. The study examines cardiac structure, rhythm, function, and blood flow in more detail than a routine obstetric ultrasound.
• Third trimester. A later study may recheck an earlier finding, follow a changing lesion or rhythm, or clarify incomplete views. Fetal position, bone shadowing, and late referral can limit images, and postnatal echocardiography may still be needed.