Prenatal Screening and Diagnostic Tests
Frequently additional care and testing are required during a high-risk pregnancy in order to give the best chance to have a healthy baby. The two Maternal Fetal Medicine practices available at St. Vincent Women's Hospital provide comprehensive screening and diagnostic testing during pregnancy. Our doctors are trained in the latest diagnostic and treatment methods used in the care of patients with complicated pregnancies. While most women give birth to healthy babies, approximately 3-5% of babies have a major birth defect or mental retardation. When an abnormality is diagnosed, this information combined with expert consultation and genetic counseling can help to make important decisions about pregnancy management.
Screening options are available to provide a risk assessment for specific birth defects during pregnancy and involves no risk of miscarriage. Many screening options are available including first trimester screening (which involves an ultrasound as well as blood work), maternal serum screening, and second trimester ultrasound screening. It is up to you and your primary obstetric provider to decide which one is best for you.
A positive screening result does not necessarily mean a birth defect is present, but indicates that the pregnancy is at increased risk for one of these conditions. Genetic counseling is available to help explain your results and review options such as ultrasound and diagnostic procedures that are available.
Diagnostic procedures have greater than 99% accuracy for detection specific abnormalities, but are associated with a risk of miscarriage due to the procedure. These tests include amniocentesis and chorionic villi sampling (CVS) both of which are associated with a less than 1% risk of miscarriage due to the procedure.
CVS is performed during gestational weeks 10-12 and involves removing a small biopsy of the placenta under ultrasound guidance. The cells of the placenta originate from the same cells as the baby and therefore are theoretically genetically identical. CVS does not screen for open neural tube defects, such as spina bifida, therefore follow-up screening for open neural tube defects will be necessary.
Amniocentesis is performed after 14-15 weeks gestation and involves inserting a needle, under ultrasound guidance, through the abdomen and into the uterus. A small amount of amniotic fluid is then withdrawn for laboratory analysis. Recently the American College of Obstetricians and Gynecologists (ACOG) recommended that amniocentesis be offered to all pregnant women interested in diagnostic testing.
Please contact one of our available practices, the Center for Prenatal Diagnosis or the Maternal Fetal Medicine and Genetics Center for more information regarding details of available screening or diagnostic testing options.
