A fetal echocardiogram is a specialized ultrasound that focuses entirely on your baby’s heart while still in the womb. It works the same way as a regular prenatal ultrasound, using sound waves bounced off the baby’s heart to create detailed moving images, but it’s performed by a specialist and captures far more cardiac detail than a standard anatomy scan. The exam is typically done between 18 and 22 weeks of pregnancy, though earlier scans are sometimes possible.
What Happens During the Exam
The process feels very similar to a routine prenatal ultrasound. You lie on an exam table, usually in your own clothes, and the provider applies a warm gel to your abdomen. A handheld device called a transducer is then pressed against your belly and moved around to capture different angles of the baby’s heart. The transducer sends out high-frequency sound waves that bounce off the heart’s structures and return as images on a monitor. You may feel some pressure as the provider adjusts the transducer’s position, but the exam is painless and involves no needles, radiation, or medication.
The main difference from a standard ultrasound is how long it takes and how many views are captured. A fetal echo can last anywhere from 30 minutes to over two hours, depending on the baby’s position and how cooperative the baby is during the scan. If the baby is facing away or moving frequently, the sonographer may need to wait or ask you to shift positions to get a clearer view. The specialist methodically works through a series of cross-sectional images of the heart, checking each chamber, valve, and major blood vessel.
Views the Specialist Captures
The exam follows a structured sequence designed to evaluate the heart from multiple angles. The first step is confirming where the heart sits in the chest and which direction it faces. From there, the cornerstone image is the four-chamber view, which shows both upper chambers (atria) and both lower chambers (ventricles) of the heart in a single frame. This view alone can reveal problems like chambers that are too large, too small, or missing entirely.
Additional views assess the outflow tracts, the pathways where blood exits the heart into the major arteries. A three-vessel and trachea view captures the aorta, the pulmonary artery, and the superior vena cava in relation to the windpipe. Adding these views significantly improves the exam’s ability to catch defects. Studies show that using the four-chamber view alone detects about 49% of congenital heart defects, while combining it with outflow tract and three-vessel views raises that detection rate to roughly 84%.
Transvaginal Versus Abdominal Approach
The vast majority of fetal echocardiograms are done through the abdomen. In some cases, particularly for early scans between 11 and 14 weeks, a transvaginal probe may be used instead. The transvaginal approach places the transducer closer to the uterus and can produce clearer images when the baby is still very small. After about 18 weeks, the abdominal approach provides excellent image quality and is the standard method.
How to Prepare
Unlike some early prenatal ultrasounds, you do not need a full bladder for a fetal echo. There’s no fasting, no dietary changes, and no special preparation required. Wearing comfortable, loose-fitting clothing that allows easy access to your abdomen can make things more convenient, but you typically won’t need to change into a gown. Bringing your medical records and any previous ultrasound results can help the team interpreting your scan.
Why You Might Be Referred
Not every pregnancy requires a fetal echocardiogram. Your provider will refer you if certain risk factors are present. Common reasons include a family history of congenital heart disease in a parent or sibling, maternal diabetes, autoimmune conditions like lupus, exposure to certain medications (particularly ibuprofen and related anti-inflammatory drugs), rubella infection during pregnancy, and conception through IVF. An abnormal finding on a routine anatomy scan is another frequent trigger.
Risk level matters for how much the exam can catch. In high-risk pregnancies, fetal echocardiography detects about 85% of congenital heart defects. In low-risk pregnancies where the scan is done as a screening measure, that sensitivity drops to around 45%. This isn’t because the technology works differently; it’s because certain defects are more subtle and more likely to appear in otherwise unremarkable pregnancies.
How Accurate the Results Are
A large meta-analysis of fetal echocardiography studies found an overall detection rate of about 69% for congenital heart defects, with a specificity of 99.8%. That high specificity means false positives are extremely rare: if the scan says the heart looks normal, it almost certainly is. The detection rate improves later in pregnancy, rising from about 61% in the second trimester to 77% when scans extend into the third trimester, because the heart is larger and easier to image in detail.
Some defects are easier to spot than others. Major structural problems like a missing chamber or a severely malformed valve are reliably detected. Smaller holes between chambers or mild valve abnormalities can be harder to identify prenatally and may only become apparent after birth.
What Happens After the Scan
The images are typically reviewed by a pediatric cardiologist or a maternal-fetal medicine specialist, sometimes during the appointment itself and sometimes afterward. In many centers, the specialist performing the scan can give you preliminary findings before you leave. A full interpretation may take a few days if the images need additional review. If the heart looks normal, no further cardiac testing is usually needed before delivery. If an abnormality is found, the team will discuss what it means, whether follow-up scans are needed as the pregnancy progresses, and what to expect at delivery, including whether your baby might need care at a hospital with a pediatric cardiac program.