Prenatal Screening & Diagnostic Tests
When routine prenatal tests detect a possible health issue with your unborn child, you might want to consider more advanced testing to be sure of the diagnosis.
This information can help your health care team manage fetal conditions during your pregnancy and investigate possible in-utero treatment options.
It also means that you and your health care team can better prepare for the delivery of a child with a health problem that might need intervention immediately upon birth.
We offer a full spectrum of both screening and diagnostic tests to evaluate the health of the fetus, placenta, umbilical cord and uterine environment.
Screening tests are less invasive, but only predict the likelihood of a problem.
Nuchal translucency (NT) screening
This exam is usually included in the 11-14 week ultrasound, and is used as a screening tool for chromosome, cardiac and structural abnormalities. Anatomy that can be seen in the first trimester will be assessed at this time as well as a measurement of a fluid space at the back of the neck known as the nuchal translucency. This test may be done in conjunction with other genetic screening.
First trimester screen
This blood test looks for biochemical markers of Down syndrome, so results might be "a 1 in 600 chance of Down Syndrome."
Maternal serum AFP
This measures a protein called alpha-fetoprotein in the mother's blood, and screens for neural tube defects such as spina bifida.
Ultrasound is used to estimate the age or size of a baby, to look for birth defects or observe a baby's activity and environment to evaluate well-being. Evaluations of the placenta, uterus and cervix also contribute information about possible risks to the pregnancy. Learn more about the ultrasound tests
Detailed fetal anatomy survey – level 2 ultrasound
This is offered in the second trimester, usually between 18-22 weeks, and evaluates the size of the fetus along with a comprehensive assessment of the fetal anatomy.
An evaluation of your baby’s(s) internal organ systems will also include the brain, spine, limbs as well as detailed cardiac views and gender (if desired). The placenta and maternal structures will also be assessed at this time.
Used in high risk pregnancies, a fetal echocardiogram can be performed at any time in the second and third trimesters.
It evaluates the fetus' cardiac structures and function. Detailed measurements of the chambers, valves, vessels and other structures of the heart will be performed to include Color and Spectral Doppler evaluations for cardiac hemodynamics.
Follow-up growth ultrasound
Follow up ultrasounds are preformed to evaluate your baby’s(s) size and growth patterns, monitor amniotic fluid levels and assess placental function and fetal well-being.
Biophysical profile and fetal Dopplers
If the clinical need arises, your physician may request a biophysical profile—typically done in the third trimester—to ensure your baby(s) are not under any stress. Your amniotic fluid is measured and the baby's(s) movement and breathing are assessed.
Ultrasound Doppler flow is also occasionally measured in blood vessels to determine the speed and pattern of flow to evaluate if your baby’s(s) are receiving sufficient nutrients and oxygen.
This exam can be done during any trimester. In the first trimester, it is often used to obtain accurate measurements of the developing fetus and evaluate the maternal anatomy. In the second and third trimesters, it is commonly used to evaluate the length of the cervix, screen for preterm labor and assess the location of the placenta.
Diagnostic tests are more invasive, but can actually confirm a problem suspected after screening.
Before any tests, we will thoroughly discuss the potential risks, benefits and possible fetal conditions with you.
Chorionic villus sampling (CVS)
You may be offered CVS if you have certain risk factors for a birth defect or genetic disease. A small sample of cells (called chorionic villi) is taken from the placenta where it attaches to the wall of the uterus.
CVS can help identify such chromosomal problems as Down syndrome or genetic diseases such as cystic fibrosis, Tay-Sachs and sickle cell anemia.
Amniocentesis, typically performed between 16 and 18 weeks, uses a thin needle to withdraw a small amount of amniotic fluid from the sac surrounding your baby. The fluid is examined to detect physical abnormalities such as Down syndrome or neural tube defects, such as spina bifida.
Amniotic fluid samples can also be DNA tested to identify a range of genetic disorders, such as cystic fibrosis and fragile X syndrome.
Percutaneous umbilical cord blood sampling
Percutaneous umbilical cord blood sampling withdraws a blood sample from the umbilical cord while the fetus is still in the uterus to detect and treat blood conditions, such as fetal anemia. It is typically done after 18 weeks of pregnancy
The decision is yours
Ultimately, the decision to pursue prenatal testing is up to you. We recommend that you discuss the risks and benefits with your OB or midwife. You might also meet with our genetic counselor for a more thorough evaluation.
Our genetic counselor can help you understand:
- the odds of your baby developing a particular condition
- how the condition would impact your baby's physical and mental development and quality of life
- possible treatment options, either during pregnancy or after birth
Taking the time to evaluate your options will help you make the best decision for you and your baby.
If you would like to schedule an appointment with a genetic counselor, please call us at 425.899.2200.
For more information, and to best prepare you for a discussion with your provider, please first watch this video, created by our own genetic counselors.