How are birth defects diagnosed?
How are birth defects diagnosed?
During pregnancy you may choose to be screened for birth defects and genetic disorders with ultrasounds or blood tests. If a screening test shows something abnormal, a diagnostic test is often recommended. First trimester screenings check for problems with your baby’s heart, and for chromosomal disorders such as Down syndrome. The screening tests include:
- Maternal blood screen. Blood tests can measure protein levels or circulating free fetal DNA in maternal blood. Abnormal results can indicate increased risk of a fetal chromosomal disorder.
- Ultrasound. An ultrasound looks for extra fluid behind your baby’s neck. That could be a sign of increased risk of a heart defect or chromosomal disorder.
Second trimester screenings check for problems with the structure of your baby’s anatomy. The tests include:
- Maternal serum screen. Blood tests in the second trimester can screen for chromosomal disorders and/or spina bifida.
- Anomaly ultrasound. An anomaly ultrasound checks the size of the baby and checks for birth defects.
More tests may be recommended if a screening test is abnormal. Such diagnostic tests are also offered to women with higher risk pregnancies. The tests include:
- Fetal echocardiogram. This is a focused ultrasound of your baby’s heart, and may be ordered in certain high risk pregnancies, or if a heart defect is suspected on anomaly ultrasound. Not all heart defects can be seen before the birth.
- Fetal MRI. This may be ordered in cases of suspected birth defects, particularly of the baby’s brain or nervous system
- Chorionic villus sampling. Your healthcare provider will collect a very small piece of the placenta for this test. It will be examined for chromosomal or genetic disorders.
- Amniocentesis. Your healthcare provider will collect a small amount of amniotic fluid. Cells are tested for chromosomal disorders and genetic problems like cystic fibrosis or Tay-Sachs disease. Amniocentesis can also test for certain infections such as cytomegalovirus (CMV).
Many birth defects may not be diagnosed until after your baby is born. They may be seen immediately, like a cleft lip, or diagnosed later. Keep an eye on your baby’s health and report any symptoms to your healthcare provider. Further tests may be needed.