Fetal echocardiography is an ultrasound test performed during pregnancy to evaluate the heart of an unborn baby.
Echocardiography assesses the heart's structures and function. A small probe called a transducer (similar to a microphone) is placed on the mother's abdomen, and it sends out ultrasonic sound waves at a frequency too high to be heard by the human ear. When the transducer is placed in certain locations and at certain angles, the ultrasonic sound waves move through the mother's and baby's skin and other body tissues to the baby's heart tissues, where the waves bounce (or "echo") off of the heart structures. The transducer picks up the reflected waves and sends them to a computer. The computer interprets the echoes into an image of the heart walls and valves.
Fetal echocardiography can help detect heart abnormalities before birth, allowing for faster medical or surgical intervention once the baby is born. This improves the chances of survival after delivery for babies with severe heart defects.
When is a fetal echocardiogram necessary?
It is not necessary for all pregnant women to receive a fetal echocardiogram. The prenatal ultrasound tests that are done prior to birth can give information about whether the fetal heart has developed all four chambers. Most unborn babies do not require any further testing.
Situations in which a fetal echocardiogram may be necessary include the following:
- there is a sibling who was born with a congenital (present at birth) heart defect
- there is family history of congenital heart disease in closely related blood relatives, such as parents, aunts or uncles, or grandparents
- the pregnancy resulted from in vitro fertilization
- a chromosomal or genetic abnormality is discovered in the fetus
- the mother has taken certain medications that may cause congenital heart defects, such as anti-seizure medications or prescription acne medications
- the mother has abused alcohol or drugs during pregnancy
- the mother has diabetes, lupus, phenylketonuria or a connective tissue disease
- the mother has had rubella during pregnancy
- a routine prenatal ultrasound has discovered possible heart abnormalities
- a routine prenatal ultrasound has identified other congenital (present at birth) anomalies, such as kidney, brain or bone abnormalities
- twin pregnancy where the twins share a common placenta (monochorionic twins)
Fetal echocardiograms are usually performed in the second trimester of pregnancy, at about 18 to 24 weeks.
How is a fetal echocardiogram performed?
Fetal echocardiograms are performed by pediatric cardiologists, maternal fetal medicine specialists, or radiologists with special training in fetal echocardiography. The test is typically performed by placing a probe over the mother's abdomen to visualize the fetal heart.
During the test, the transducer probe will be moved around to obtain images of different locations and structures of the fetal heart. Techniques sometimes used to obtain detailed information about the fetal heart include the following:
- 2-D (two-dimensional) echocardiography. This technique is used to "see" the actual structures and motion of the heart structures. A 2-D echo view appears cone-shaped on the monitor, and the real-time motion of the heart's structures can be observed. This enables the doctor to see the various heart structures at work and evaluate them.
- 4-D (four-dimensional) ultrasonography.4-D ultrasonography uses a special probe that is capable of acquiring a series of images of the beating fetal heart. These images can be seen in multiple planes at the same time on the screen. They can also be reconstructed to provide a more realistic picture of the fetal heart. This helps the doctor performing the exam better understand and diagnose diseases that can affect a baby's heart.
- Doppler echocardiography. This Doppler technique is used to measure and assess the flow of blood through the heart's chambers and valves. Doppler can also detect abnormal blood flow within the heart, which can indicate problems such as an opening between chambers of the heart, a problem with one or more of the heart's four valves, or a problem with the heart's walls.
- Color Doppler. Color Doppler is an enhanced form of Doppler echocardiography. With color Doppler, different colors are used to designate the direction of blood flow. This simplifies the interpretation of the Doppler images.
Other tests and procedures that may be needed include:
- Additional ultrasounds or echocardiograms, which may be performed to confirm diagnosis, follow fetal growth, and monitor fetal well-being.
- Amniocentesis, which is a test performed to identify chromosomal and genetic disorders, as well and certain birth defects. The test involves inserting a needle through the abdominal and uterine wall into the amniotic sac to retrieve a sample of amniotic fluid.
- Genetic counseling, which can provide an assessment of heritable risk factors. It can also give information to patients and their relatives about the consequences of a disorder, the probability of developing or transmitting the disorder, and ways in which it can be prevented, treated and managed.