In an abdominal ultrasound, the person performing the test places a clear, water-based gel on your belly and then moves a hand-held probe over the area. The probe sends out sound waves, which bounce off the baby’s heart and create a picture of the heart on a computer screen.
In a transvaginal ultrasound, a much smaller probe is placed into the vagina. A transvaginal ultrasound can be done earlier in the pregnancy and produces a clearer image than an abdominal ultrasound.
How to prepare for the test
No special preparation is needed for this test.
How the test will feel
The conducting gel may feel slightly cold and wet. You will not feel the ultrasound waves.
Why the test is performed
This test is done to detect a heart problem before the baby is born. It can provide a more detailed image of the baby’s heart than a regular pregnancy ultrasound.
The test can show:
Blood flow through the heart
Structures of the baby’s heart
The test may be done if:
A sibling or other family member had a heart defect or heart disease
A routine pregnancy ultrasound detected an abnormal heart rhythm or possible heart problem in the unborn baby
There are no known risks to the mother or unborn baby.
Some heart defects cannot be seen before birth, even with fetal echocardiography. These include small holes in the heart or mild valve problems. Sometimes it may not be possible to see every part of the large blood vessels leading out of the baby's heart.
If the health care provider finds a problem in the structure of the heart, a detailed ultrasound may be done to look for other problems with the developing baby.
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Tutschek B, Schmidt KG. Techniques for assessing cardiac output and fetal cardiac function. Semin Fetal Neonatal Med. 2011 Feb;16(1):13-21.
Kimberly G Lee, MD, MSc, IBCLC, Associate Professor of Pediatrics, Division of Neonatology, Medical University of South Carolina, Charleston, SC. Review provided by VeriMed Healthcare Network. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.