What Types of Genetic Testing Are Available?

Prenatal genetic testing gives expectant parents information about their unborn child’s DNA and any risk of certain genetic disorders. Genetic disorders include chromosomal abnormalities (aneuploidy) like Down syndrome, as well as inherited conditions like sickle cell disease and cystic fibrosis.

Genetic disorders can significantly impact a fetus’s health and development, and genetic testing offers a way to identify these conditions early in pregnancy. However, genetic testing is optional, so it’s important to learn your options and find out when these tests might be recommended.

Daniel McDonald, MD, Marc Wilson, MD, and our team at OB/GYN Specialists offer prenatal care and genetic testing, and we’re here to help you decide if these optional screenings are right for you.

Genetic screening tests

There are two main types of prenatal genetic testing: screenings and diagnostic testing. If you want to have genetic testing during your pregnancy, our team starts with screenings to identify the possibility of some common genetic disorders.

Most genetic screening tests take place during the first and second trimesters of pregnancy. There are a few different types, depending on the risk factors that you and your partner may have.

Nuchal translucency screening

Nuchal translucency screening is a type of ultrasound used to evaluate a fetus’s risk of Down syndrome, other types of aneuploidy, or physical defects of the heart, abdomen, or skeleton.

During the ultrasound screening, your doctor measures the space at the back of your fetus’s neck. This screening ultrasound typically occurs in the first trimester.

Cell-free fetal DNA testing

Cell-free fetal DNA testing is a blood test that examines fetal DNA found in the mother’s bloodstream. This screening test can identify an increased chance of genetic disorders, like Down syndrome. It can also identify a baby’s sex and blood type, and be done as early as 10 weeks.

Quad blood testing

Quad blood testing measures the level of four substances in the mother’s blood to screen for genetic disorders, including Down syndrome and neural tube defects. This test usually occurs in the second trimester, between weeks 15-22.

Genetic diagnostic tests

Genetic screening tests identify possible issues in pregnancy, but screenings alone can’t diagnose genetic conditions. If you had a screening test that indicates a potential genetic condition, our team may recommend diagnostic testing to reach a conclusive diagnosis.

Diagnostic testing can carry a risk of miscarriage, so it’s important to talk with your doctor to determine if these tests are right for you. Two of the most common diagnostic tests are:

Amniocentesis

Amniocentesis is a type of diagnostic testing that requires taking a sample of the amniotic fluid surrounding your fetus. This procedure is generally safest between weeks 15-20 of pregnancy. Your doctor uses a long needle through your belly to your uterus to take the fluid sample, which is then tested for genetic disorders.

Chorionic villus sampling (CVS)

CVS testing usually takes place between weeks 10-13 of pregnancy. Using a needle or thin tube, your doctor takes a sample of placental tissue from your uterus. The tissue is tested to identify genetic disorders like Down syndrome, trisomy 13, trisomy 18, spina bifida, and other brain or spinal conditions.

When to consider prenatal genetic testing

Genetic testing provides extra information about your pregnancy, including the risk of your baby being born with certain genetic disorders. Different types of genetic testing are available in the first and second trimesters, but it’s important to remember that genetic testing is completely optional.

Some parents-to-be choose genetic testing so they can feel more prepared about pregnancy and their baby’s health. Others choose to forgo genetic testing for various reasons.

Depending on the genetic histories of you and your partner, your doctor may recommend genetic testing. Suggesting genetic testing doesn’t mean that your fetus has a genetic condition, but testing can give us more information about your health and your pregnancy.

Even if genetic testing is recommended, it’s up to you and your partner whether you want the screenings done. To find out more about prenatal genetic testing, talk to our team at OB/GYN Specialists.