Understanding your testing options helps you prepare for the future.
Your reasons for testing may include:
concerns regarding Down syndrome and trisomy 18
concerns regarding open neural tube defects in pregnancy, such as spina bifida
a family history of Down syndrome, trisomy 18, or open neural tube defects
If you are not sure whether you should have SequentialScreenSM, please talk with your doctor, a genetic counselor or other specialist in genetics. See “Questions to Ask Your Doctor”.
SequentialScreenSM screens for:
Down syndrome and trisomy 18.
Open neural tube defects, such as spina bifida and anencephaly.
How the test works
SequentialScreenSM is a two-part screening test that provides an early, preliminary result in the first trimester and a final, complete result in the second trimester.
Approximately between your 10th and 12th week of pregnancy, a small amount of your blood is drawn to evaluate the levels of certain proteins and hormones produced during your pregnancy, and a special ultrasound measurement is taken of the back of the baby’s neck (called the nuchal translucency) to provide your risk of having a baby with Down syndrome or trisomy 18.
If you are at an increased risk, your doctor will offer diagnostic testing, such as amniocentesis or chorionic villi sampling (CVS), to confirm the results of your screening test.
If you are not at increased risk, you will return approximately between your 15th and 21st week (optimal time is 16-18 weeks) for a second blood test. Results from Part 1 and Part 2 are combined to provide a final, complete result: your risk of having a baby with Down syndrome, trisomy 18 or an open neural tube defect.
SequentialScreenSM Part 1 leads to the detection* of approximately:
70% of Down syndrome cases
80% of trisomy 18 cases
The result “final result pending second trimester sample” means that your pregnancy is not in the highest risk group for Down syndrome or trisomy 18. You will be asked to complete the second part of this screen.
The result “screen positive” means there is an increased risk of your baby having Down syndrome or trisomy 18. The next step is to talk with your doctor and/or genetic counselor about your results and your diagnostic testing options.
SequentialScreenSM Part 2 leads to the detection* of approximately:
90% of Down syndrome cases
90% of trisomy 18 cases
80% of open neural tube defects
The result “screen negative” means there is a low risk of your baby having Down syndrome, trisomy 18 or an open neural tube defect. However, in approximately 10% of pregnancies, these birth defects will not be detected through screening.
The result “screen positive” means there is an increased risk of your baby having Down syndrome, trisomy 18 or an open neural tube defect. The next step is to talk with your doctor and/or genetic counselor about your results and your diagnostic testing options.
Some factors influencing your result:
exactly how far along you are in your pregnancy when the blood sample is taken
your weight, ethnic background and age
whether you are an insulin-dependent diabetic or take certain types of medications
whether you have had a prior pregnancy or a close relative affected with Down syndrome, trisomy 18, or an open neural tube defect
If a screening test is positive, it does not mean your baby has a birth defect. In fact, most women who have positive screening results have healthy babies.
Screening testing helps doctors to identify women who should be offered additional testing. Your doctor may recommend:
a more detailed ultrasound examination (which can often identify an open neural tube defect)
diagnostic testing, such as amniocentesis for chromosome abnormalities and open neural tube defects or chorionic villi sampling (CVS) for chromosome abnormalities.
What's not detected
Every pregnancy has some risk (3-5%) for the kinds of birth defects that cannot be diagnosed during pregnancy, such as autism, non-specific mental retardation, some genetic diseases, and some types of physical birth defects.
Risks of testing
SequentialScreenSM is a non-invasive blood test. Potential side effects from drawing blood for the test include bruising at the site or ongoing bleeding for people with bleeding disorders.
*Detection rate estimates for Genzyme maternal serum screening tests arebased on US and international studies.
SequentialScreenSM is a service mark of Genzyme Corporation.
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