Prenatal Screening and Diagnostic Tests
Additional care and testing are sometimes required to help give the best chance for a healthy mother and baby. Both the Center for Prenatal Diagnosis and the Maternal-Fetal Medicine and Genetics Center available at St. Vincent Women's Hospital, provide comprehensive prenatal screening and diagnostic testing. Our doctors are trained in the latest diagnostic and treatment methods used in the care of women with complicated pregnancies. While most women give birth to healthy babies, approximately 3-5% of babies have a major birth defect or health challenge. When an abnormality is diagnosed, this information combined with expert consultation and genetic counseling can help make important decisions about pregnancy management.
We offer a variety of screening options that provide a risk assessment for specific birth defects during pregnancy. These screening options include first trimester screening (which involves an ultrasound and blood work), maternal serum screening (may include sequential screening or the triple/quad screen), and second trimester ultrasound screening. These non-invasive screening options are not associated with a risk of miscarriage or other complications for the pregnancy. You and your primary obstetric care provider will decide which screening option is best for you. It is important to remember that a “positive”(increased risk) screening result does not necessarily mean a birth defect is present. It simply means that the pregnancy is at increased risk for certain conditions and additional evaluations may be helpful. Genetic counseling is available to help explain your results and review your all of your options including ultrasound and further diagnostic testing.
Diagnostic testing is more than 99% accurate in the detection of certain specific fetal abnormalities. However, there are risks associated with diagnostic procedures, including miscarriage. Diagnostic tests such as amniocentesis and chorionic villi sampling (CVS) both carry a less than 1% risk of miscarriage. Recently, the American College of Obstetricians and Gynecologists (ACOG) recommended that diagnostic testing be offered to all pregnant women who are interested in such testing. Diagnostic tests offered include:
- Amniocentesis – Performed after the second trimester, typically after 14-15 weeks gestation. This procedure involves inserting a needle, under ultrasound guidance, through the abdomen and into the uterus. A small amount of amniotic fluid is withdrawn for laboratory analysis.
- CVS – Typically performed during the first trimester - most commonly between 10-12 weeks gestation. During this procedure, a small biopsy of the placenta will be removed. This procedure is done under ultrasound guidance and can be done abdominally by inserting a thin needle through the abdomen or cervically by inserting a thin catheter through the cervix to obtain the small piece of the placenta. The cells of the placenta originate from the same cells as the baby and therefore are theoretically genetically identical. There is some chance of complicated results with CVS, which can be discussed with your physician or genetic counselor prior to the procedure.
- Additional procedures/testing options may be available depending on your unique situation such as fetal blood sampling, fetal blood transfusions, fetal thoracic (chest) and bladder shunting, and PUBS (percutaneous umbilical blood sampling).
For more information, please contact the Center for Prenatal Diagnosis at (317) 415-8070 or the Maternal-Fetal Medicine and Genetics Center at (317) 415-8100.