Fetal Echocardiography In-Depth

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What is fetal echocardiography?

Fetal echocardiography is an ultrasound test performed during pregnancy to evaluate the heart of the unborn baby.

How does a fetal echocardiogram work?

  • A small probe called a transducer (similar to a microphone) is placed on the mother's abdomen and sends out ultrasonic sound waves at a frequency too high to be heard.
  • When the transducer is placed in certain locations and at certain angles, the sound waves move through the mother's and baby's skin 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 fetal heart abnormalities before birth, allowing for faster medical or surgical intervention once the baby is born. This improves the chance of survival after delivery for babies with serious heart defects.

When is a fetal echocardiogram necessary?

Not all pregnant mothers need an echocardiogram. The standard prenatal ultrasound tests can give information about whether the fetal heart has developed with all four chambers and most pregnant women don’t need any further testing. Situations in which a fetal echocardiogram may be necessary include:

  • if a sibling was born with a congenital (present at birth) heart defect
  • a family history of congenital heart disease (such as parents, aunts or uncles or grandparents)
  • a chromosomal or genetic abnormality discovered in the fetus
  • if a mother has taken certain medications that may cause congenital heart defects, such as anti-seizure medications or prescription acne medications
  • if a woman has abused alcohol or drugs during pregnancy
  • if a woman has diabetes, phenylketonuria, or a connective tissue disease such as lupus
  • if a woman has had rubella during pregnancy
  • a routine prenatal ultrasound has discovered possible heart abnormalities

Fetal echocardiograms are usually performed in the second trimester of pregnancy, at about 18 weeks. The test is sometimes done earlier in pregnancy using transvaginal ultrasound (the ultrasound probe is inserted in the mother's vagina), but will be repeated later to confirm any findings.

How is a fetal echocardiogram performed?

A fetal echocardiogram is performed by a pediatric cardiologist or a maternal fetal specialist (also called a perinatologist) who is specially trained. The test may be done using an abdominal or transvaginal ultrasound.

  • Abdominal ultrasound - In an abdominal ultrasound, gel is applied to the abdomen and the ultrasound transducer glides over the gel on the abdomen to create the image.
  • Transvaginal ultrasound - In a transvaginal ultrasound, a smaller ultrasound transducer is inserted into the vagina and rests against the back of the vagina to create an image. A transvaginal ultrasound produces a sharper image than abdominal ultrasound and is used most often during early pregnancy.

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:

  • 2-D (2-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 physician to see and evaluate the various heart structures at work.
  • Doppler echocardiography - This Doppler technique is used to measure and assess the flow of blood through the heart's chambers and valves. The amount of blood pumped out with each beat is an indication of the heart's functioning. Also, Doppler can detect abnormal blood flow within the heart, which can indicate such problems 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.
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