Fetal ultrasound is a test done during pregnancy that uses reflected sound waves to produce an image of the fetus, placenta and amniotic fluid (the liquid that surrounds the fetus). Fetal ultrasound is a safe way to check for problems and obtain information about a fetus, such as its size, position, and anatomy. It does not use X-rays or other types of radiation that may be harmful. It can be done as early as the 5th week of pregnancy.
A fetal echocardiogram is a non-invasive imaging technique used during pregnancy for diagnosis of heart problems in the fetus. It is very safe for the mother and the baby and does not cause harm even if repeated on multiple occasions. Echocardiography uses ultrasonic waves to visualize the fetal heart and its structures and evaluates the heart rate and rhythm. Abnormal fetal heart rates and rhythms may represent an arrhythmia. Studies have shown that prenatal diagnosis of fetal cardiac disease has improved the overall outcome and smooths the transition from birth to immediate cardiac care.
- A fetal echocardiogram may be needed for several reasons:
- Cardiac or any other organ system anomaly associated with a heart defect is suspected on the obstetrical ultrasound
- History of congenital heart disease in the siblings, parents or other family members
- Mother's exposure to drugs, medicines and certain infections
- Maternal diabetes or connective tissue diseases such as SLE (lupus)
- Chromosomal abnormality detected by amniocentesis or other tests (especially Down syndrome)
- Abnormal heart rhythm (tachycardia, bradycardia or skipped beats)
Although a fetal echocardiogram can be obtained as early as 15 weeks, the preferred gestational age is between 18-22 weeks. Depending on the fetal position, maternal factors or early gestational age, the fetal echocardiogram may need to be repeated later for optimal visualization. If a congenital heart defect is diagnosed in a fetus and depending on the defect, fetal echocardiogram may be repeated more than once during the pregnancy to assess the progression or fetal compromise. If a fetal arrhythmia is detected, serial fetal echocardiograms may be needed to adequately follow the fetus prior to delivery.
Magnetic Resonance Imaging (MRI) is another non-invasive adjunct to prenatal ultrasound. It can provide significant additional information that improves diagnostic accuracy in evaluation of the fetal brain, spine, neck, chest, abdomen, and urinary tract in sectional planes. A fetal MRI is interpreted by the Texas Fetal Center’s dedicated pediatric radiologist who specializes in fetal imaging.
MRI uses no radiation, but uses a magnetic field to align the nuclear magnetization of hydrogen atoms of water in the body. This means that an MRI is safe for mother and baby. Common conditions that may require a fetal MRI include intracranial or brain problems, lung masses, and tumors. As improvements in MRI technology continue, more and more fetal structures may be evaluated with MRI.