PAMPHLET

Second Trimester Maternal Serum AFP and
freeBeta^tmPrenatal Screening

What Does the Test Tell My Healthcare Provider and me?
This test identifies women who have an increased risk of having a baby with certain birth defects. This test detects 98% of open spine and skull birth defects, about 60% of open abdominal defects, 80% of Down syndrome, 70% of Trisomy 18 and some other chromosomal abnormalities. It also provides your healthcare provider other valuable information about your pregnancy.

What Are AFP and freeBeta ?
Maternal blood alpha fetoprotein (AFP) is a protein produced by your baby. FreeBeta (human chorionic gonadotrophin) is produced by the placenta. These proteins are normally found in the blood of all pregnant women. To complete testing early, screening may be done at 13 weeks 4 days to 15 weeks. Screening can also be done as late as 22 weeks 3 days.

What Are Open Spine, Skull and Open Abdomen Defects?
These birth defects occur when the developing baby's spine/skull/or abdomen does not close completely. They are the most common types of birth defects occurring in about 1 to 2 out of 1000 liveborn babies. About 95% occur in families with no history of these defects. These babies have mild to severe problems. If the defect occurs in the skull (anencephaly), the baby cannot survive long after birth. If the defect is in the spine (spina bifida), nerve damage occurs, and the baby usually has paralysis from the point of the defect and below. Surgery can not correct many of the associated problems and life span maybe reduced. Open abdomen defects also vary in severity. Surgery after birth is helpful in some but not all affected babies.

What are Down Syndrome and Trisomy 18?
These are chromosomal abnormalities are caused by the baby having an extra chromosome in each cell. The extra chromosome, which contains thousands of genes, can have many effects, including birth defects and mental retardation. The chance of having a baby with an extra chromosome increases with parents' age.

Who Should Have Screening?
Screening should be offered to all pregnant women who are less than 35, and whose babies do not have an increased risk for an ONTD or chromosomal abnormalities.

The American College of Obstetricians and Gynecologists (1994) and the American College of Medical Genetics (1993) recommend women who will be 35 or older at delivery or have a positive family history should consider amniocentesis or CVS for prenatal chromosome testing, to diagnose 99.9% of all chromosomal abnormalities. Screening is not a substitute for amniocentesis because: 1) screening does not give a diagnosis, 2) screening estimates a risk for only 2 chromosomal abnormalities, 3) screening will miss many of the hundreds of other types of chromosomal abnormalities, 4) screening may falsely reassure some patients who still have an increased chromosomal abnormality risk due to age. If you are over 37, screening is unlikely to reduce your risks.

What is a Genetic Counselor?
A genetic counselor provides information and support to families, individuals and prospective parents concerning hereditary diseases and birth defects. The genetic counselor performs a comprehensive review of your medical, family and/or pregnancy history, and evaluates your risk factors. Genetic testing options and the risks and benefits of testing are explained.

ADVANTAGES OF ULTRA-SCREEN SCREENING:

1. AFP/freeBeta has 15-24% higher detection for ONTD, open abdominal defects, and chromosome abnormalities than other screening tests.
2. Only half as many patients receive an increased risk result as with other tests.
3. Testing can be performed as early as 13 weeks 4 days and as late as 22 weeks 3 days versus 15-20 weeks for other tests.
4. Earliest testing provides earlier options for follow-up diagnostic testing if needed.

What If My Test Shows an Increased Risk?
An increased risk does not mean an abnormality has been diagnosed. Your healthcare provider will discuss additional testing which can determine whether your baby has an abnormality or if there are other explanations for this test result. For example, you may be further along in the pregnancy than previously thought, you may have twins, or the protein levels may be normal variations. You may be offered a second AFP test, genetic counseling, an ultrasound exam, and/or amniocentesis for chromosome and AFP testing. These diagnostic tests are very safe and accurate.

What if my screening test does not show an increased risk?
This is good news, however, AFP/freeBeta screening cannot eliminate the risk for these birth defects. Also, Down syndrome and trisomy 18 makeup only about half of all chromosomal abnormalities. Chromosome screening does not estimate a risk for the other half of other chromosomal abnormalities.

How Accurate Is AFP/freeBeta Screening?
AFP/freeBeta has been documented to be the most accurate second trimester screening test available. These tests do not eliminate the possibility the fetus may have birth defects, mental retardation, Down syndrome, trisomy 18, other chromosome abnormalities, or other abnormalities not detectable by these screening tests. Screening will not detect small or closed spine and skull defects, open abdominal defects and pregnancies with perinatal complications. Multiple gestation screening is not as sensitive as singleton. All reports rely on the accuracy of the patient’s clinical information.

PLEASE REMEMBER: The decision whether to have the screening tests performed is your personal decision. If these tests show you have an increased risk, it does not mean a problem has been diagnosed, only that further evaluation of your pregnancy is indicated. The majority of women with an increased risk are found to have healthy babies after further testing.

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Last modified: May 25, 2004 04:26 PM
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