Prenatal Screening Options:
First Trimester Screening
First trimester screening includes a blood test and an ultrasound exam. During this ultrasound examination, a detailed measurement is taken of a pocket of fluid located at the back of the baby’s neck, called the nuchal translucency (NT). This ultrasound is different from the ultrasounds performed at most doctors’ offices because our sonographers have special training on taking NT measurements. This ultrasound must be performed between 10 and 14 weeks at the end of the first trimester.
The combination of the blood test and ultrasound provide information about the chances for your baby to be affected with either Down syndrome or another chromosome condition, trisomy 18. If your results are positive, you may be able to meet with our geneticist to discuss additional testing options right away.
Second Trimester Quad Screening
The second trimester quad screening is a blood test that is typically performed through your primary OB’s office. This blood test measures the levels of four proteins (thus the name “quad” screening) that are produced by the pregnancy, but found in the mother’s blood. The levels of these four proteins are used to calculate the chance of a baby being born with Down syndrome (a chromosome condition); trisomy 18 (a more severe chromosome condition); Smith-Lemli-Opitz syndrome (a condition that affects the way a baby processes cholesterol); and neural tube defects/ventral wall defects (openings along the baby’s spine or abdomen).
The blood sample for this test is usually taken between 15-20 weeks of the pregnancy to provide you with accurate results
Full Integrated Screening
Full integrated screening is done by combining the first trimester screening with the second trimester quad screen. With this screening, a preliminary risk assessment for Down syndrome and trisomy 18 is given after the first trimester screen is completed. Final risk assessments are given after the quad screen is completed. Full integrated screening has a higher detection rate for Down syndrome and trisomy 18 than either first trimester screening or quad screening alone.
If you are unable to complete all parts of the full integrated screening, you can still increase the detection rate of your prenatal screening by combining some of components. However, with these tests you will not receive any results until after the quad screen is complete.
What Happens After a Positive Result?
If you are referred to our office due to a positive result, it is Important to remember that does not mean that your baby is affected. It just means that the chance for the baby to have a problem is increased. False negative results are also possible with screening tests. Even with a normal screening result and a normal ultrasound it is possible that the baby may have a chromosome condition or birth defect. A negative result on these tests simply indicates that the chance for the baby to have a problem is decreased.
At your appointment, you will meet with our geneticist that will review all of your screening results and will answer all of your questions. Though most of the conditions detected by these screening tests are not typically inherited, information regarding your family and pregnancy history will be reviewed. In addition, other available testing options such as CVS, amniocentesis, and ultrasound will be discussed.