Different types of genetic testing during pregnancy

Types of Genetic Screenings and Diagnostic Testing during Pregnancy

Genetic Blood Test
A genetic blood test is available to women to provide screening for some disorders. Screening tests alone are not diagnostic. If a blood test finds a possible problem, a prenatal diagnostic test may be recommended to confirm a diagnosis. These diagnostic tests include chorionic villus sampling (CVS) or amniocentesis and are used to perform fetal chromosome analysis or microarray analysis of fetal cells.

Table of Contents Show

Types of Genetic Screenings and Diagnostic Testing during Pregnancy
A Word of Caution About Genetic Testing During Pregnancy
Here for You, Before You Need Us
Genetic screening tests
Nuchal translucency screening
Cell-free fetal DNA testing
Quad blood testing
Genetic diagnostic tests
Amniocentesis
Chorionic villus sampling (CVS)
When to consider prenatal genetic testing
What are the four types of genetic testing?
What are 2 common types of genetic testing?
What is the 3 most common prenatal tests for diagnosing birth defects?
What are the 3 common prenatal tests?

Chorionic Villus Sampling (CVS)
Chorionic villus sampling (CVS) is a diagnostic test usually performed between the 10th to 12th weeks of pregnancy. The perinatologist gently suctions a small piece of the placenta on the outside of the fetal sac to obtain fetal tissue and cells in order to look at fetal chromosomes and/or DNA, and potentially other genetic conditions in the fetus.

Amniocentesis
A genetic amniocentesis is a diagnostic test usually performed between weeks 16 to 20 of a woman’s pregnancy. The perinatologist inserts a hollow needle to remove a small amount of amniotic fluid from around the developing fetus. This fluid has fetal cells floating in it that allow the laboratory to study fetal chromosomes by routine analysis or by microarray, as well as to obtain fetal DNA for other types of genetic testing depending on the family history. This fluid also allows testing for neural tube defects (spina bifida) or abdominal wall defects (gastroschisis, omphalocele) in the developing fetus.

There is another form of amniocentesis that is not genetic, but rather performed when there’s a risk of premature birth, to check if a baby’s lungs have matured; this is not a genetic test.

A Word of Caution About Genetic Testing During Pregnancy

Although advances in genetic testing have improved doctors’ ability to diagnose and treat certain illnesses, there are still some limits. Genetic tests can identify a particular problem in a chromosome or gene, but can’t always predict how severely a person who has the condition will be affected, as all of us are unique. We will do everything we can to help provide the support and information you need, with the understanding that there may be some things we won’t know until your baby is born.

Learn more about prenatal genetic testing at our affiliate laboratory.

Here for You, Before You Need Us

During the course of a pregnancy, prenatal testing may identify issues with your baby that will need attention immediately after birth. You have a choice about where to bring your baby for medical care. At CHOC, our highly trained neonatologists, surgeons, geneticists and other pediatric specialists can meet with your family before birth to discuss a comprehensive plan for your baby and the tests, procedures and treatments he or she will need. Talk to your obstetrician about making CHOC the preferred hospital for your baby after birth.

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.

What are the four types of genetic testing?

Different types of genetic testing are done for different reasons:.

Diagnostic testing. ... .

Presymptomatic and predictive testing. ... .

Carrier testing. ... .

Pharmacogenetics. ... .

Prenatal testing. ... .

Newborn screening. ... .

Preimplantation testing..

What are 2 common types of genetic testing?

There are two different kinds of large-scale genetic tests. Exome sequencing looks at all the genes in the DNA (whole exome) or just the genes that are related to medical conditions (clinical exome). Genome sequencing is the largest genetic test and looks at all of a person's DNA, not just the genes.