OB/GYN: Genetic Screening Options

couple at a fertility planning session

Prenatal and Preconception Screening, Testing, and Counseling

Whether before or after conception, we offer options for screening and testing that can help in preparing for a healthy baby. Your decisions about screening and testing options are very personal ones. This document gives some basics, however your provider will also refer you for a genetic consultation. The genetic counselor will review your personal and family history and provide you with more detailed information about your screening and testing choices.

Genetic Carrier Screening involves a blood sample and can be performed prior to or during a pregnancy. It can identify those at increased risk of having a child with certain genetic conditions. Screening most often includes common disorders such as Cystic Fibrosis, Spinal Muscular Atrophy and Sickle Cell Anemia. Doing the screening before or early in pregnancy can increase your options. Expanded carrier screening panels are also available. Please speak with your provider for more information or review our Genetic Carrier Screening fact sheet.

Genetic Counseling is a routine part of the prenatal screening process for all pregnant people. It is an in person or telehealth visit, in which the genetic counselor will discuss your screening and testing options and work with you to arrange the tests you choose. This will include a discussion of risks and options for those who will be over 35 years at the time of delivery. They will also communicate results to you when completed. If results raise concerns, they will explain them and help you pursue additional screening or testing, if desired, or arrange consultations and referrals when appropriate.

Genetic counseling appointments can also be scheduled for a variety of other reasons. This includes pregnancies in which ultrasound findings have raised concern, or families who have a child or other close relative with a birth defect, physical or cognitive disabilities, or genetic disorder. Genetic counseling is also available for carriers for a genetic condition, such as Tay-Sachs, Sickle Cell Anemia, Spinal Muscular Atrophy or Cystic Fibrosis. Pregnant people who have been exposed to agents, such as medications, that may be harmful to the baby may seek genetic counseling.

Prenatal Screening includes options that can identify whether your baby is more or less likely to have certain conditions. A genetic counseling visit is typically scheduled in combination with these screens. Prenatal screening is non-invasive, uses a blood sample and ultrasound, and can start in the early stages of your pregnancy through the second trimester. Screening can't make a definitive diagnosis but will find most pregnancies with a higher risk. They carry no risk to the baby and are most often reassuring. If results indicate an increased risk for a condition, your genetic counselor or health care provider will discuss them with you, offer further testing and make a plan for further care.

Screening Options

First Trimester
  • First Trimester Screen
    • A blood sample is obtained by a finger stick combined with ultrasound to estimate the risk of Down syndrome, trisomy 13 and trisomy 18
    • This screening is done between 11 weeks and 13 weeks, 6 days
    • Results are typically available in about 5 days
  • Cell free DNA Screening: cfDNA or Noninvasive Prenatal Testing (NIPT)
    • A blood draw used to assess the risk of Down syndrome, trisomy 18, trisomy 13, and sex chromosome abnormalities
    • This is more commonly used for those at increased risk for having a baby with birth defects. These risks include advanced maternal age, history of chromosomal abnormalities, or previous abnormal screening results
    • It can be considered by a patient with a low risk pregnancy, however may not be covered by insurance
    • The test can be done after 10 weeks of pregnancy
    • Results are usually available in about 7 days
Second Trimester
  • Maternal Serum Alpha-Fetoprotein (MSAFP)
    • MSAFP is a blood draw to screen for open neural tube defects such as spina bifida and other more rare conditions
    • Typically the MSFAP is done between weeks 15 and 24 of pregnancy
  • Tetra Screen (Includes MSAFP Screen)
    • Uses a blood sample to estimate the risk of Down syndrome and trisomy 18
    • This would routinely be offered to those who have not had a first trimester screen
    • Typically this screening is done between weeks 15 and 20 of pregnancy
    • Results are usually available in about 7 days
  • Ultrasound or Sonogram
    • Uses sound waves to create computer images that can evaluate the growth and development of the baby
    • An anatomy ultrasound is routinely performed at approximately 20 weeks of pregnancy
    • Any differences or abnormalities that are found are discussed with a Maternal Fetal Medicine physician after the ultrasound. Our physician will explain the finding and discuss options for further screening, prenatal diagnosis, or special care. They may offer a visit with the genetic counselor for additional information and support.

Prenatal Diagnostic Options

Diagnostic testing is most often offered to patients who will be over 35 years at delivery, who have a positive screening results, or who have a child or other family member with a birth defect or genetic condition. Genetic counseling is provided to review these tests if they are being considered. These tests provide definitive answers about chromosome abnormalities and certain genetic disorders. Both tests obtain cells from the pregnancy without touching the baby, but each carry a small risk for complications. They are usually considered to be uncomfortable, not painful, and are short procedures. Other specialized tests can be added and will be discussed as an option with either procedure.

Chronic Villus Sampling (CVS)
  • In CVS testing, a small sample of cells is taken from the placenta, either with a vaginal or abdominal approach, under ultrasound guidance
  • The CVS is typically performed between 11 and 14 weeks of pregnancy
  • The risk for a complication that may lead to miscarriage is less than 1 in 500 (less than 0.2 of 1%)
  • Final results are typically available in about 10-14 days
  • Follow-up screening for neural tube defects will be offered with MSAFP (see page 9)
  • In amniocentesis, under ultrasound-guidance, a thin needle is used to withdraw a small amount of amniotic fluid or ‘birth’ fluid around the baby
  • The amniocentesis will not only diagnose chromosomal abnormalities, but can also diagnose neural tube defects
  • The procedure is typically performed between 15 and 20 weeks of pregnancy
  • The risk for complications that may lead to miscarriage is less than 1 in 1,000 (less than 0.1 of 1%)
  • Final results are typically available in about 10-14 days
Will my health insurance cover testing?

Most insurance plans will cover prenatal screening with first trimester screening or tetra screening. The cell free DNA screening and prenatal diagnosis are usually covered for patients at increased risk including those over 35 years old, pregnancies with abnormal screening or ultrasound, or known risk for a genetic disorder. It may be covered for low risk patients, however you would be advised to check with your insurance regarding coverage. You can be provided with codes to use in discussing this with insurance. Additionally, you may have deductibles and copays that will apply.

Additional questions to consider:

All of the referenced screening and testing is optional and there are some things you can think about as you make decisions on proceeding:

  • Whether the results will impact your choices in pregnancy
  • The accuracy of the screening or testing
  • Any risks that may be associated with the testing

Please remember that your health care provider and genetic counselor are trained to focus on your particular situation and help you make the best decision for you.

Where can I learn more?

Cancer Genetic Counseling:

Individuals with a family history of cancer or related questions are encouraged to contact the Ruth Paul Cancer Genetics and Prevention Center at 202.677.6903 or https://gwdocs.org/specialties/cancer-blood-disorders.

You will learn more and have the opportunity to ask individual questions at your genetic counseling visit. However, these websites may be helpful: