PIEDMONT OBSTETRICS AND GYNECOLOGY
TRIPLE SCREENING IN PREGNANCY
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The alpha-fetoprotein (AFP) test is a prenatal blood test. AFP is a substance produced by the liver of the fetus. Some of this protein is excreted into the amniotic fluid surrounding the fetus and a small amount passes into the mother's bloodstream. The AFP test is a part of what is called the triple test, which looks at three substances normally present in the bloodstream of pregnant women: AFP, and two pregnancy hormones called estriol and human chorionic gonadotropin (HCG). When AFP is at a high level, the fetus often has a risk of neural tube defects, which occur when the spinal cord or brain does not form completely, as in spina bifida. When combined with measurements of estriol and HCG, it can be used to screen for a high risk of Down's syndrome, a chromosomal disorder that results in mental retardation and physical abnormalities..
The AFP and the triple screen are usually done between 16 and 18 weeks after the last menstrual period. A blood sample is taken from a vein in your arm. Results are typically available within one to two weeks.
What does an abnormal test result mean?
These tests cannot diagnose a birth defect, but they can indicate when there is a high risk. An increased level of AFP may be found in the blood of a woman whose fetus has a neural tube defect. An AFP level that is lower than normal may be linked to an increased risk of Down's syndrome. Abnormal levels of HCG and estriol may also indicate chromosome abnormalities. An abnormal test result simply means that additional testing is needed. Out of every 1,000 women who take a triple screen test, as many as 100 will have an abnormal result. However, only two or three of those 100 women will have a fetus with a birth defect. For most of the rest, the abnormal result simply indicates the fetus is either a few weeks older or younger than originally thought. The range of normal results varies with the weeks of pregnancy, which is why it is important to know as close as possible the accurate gestational age of the fetus.
What tests are recommended following an abnormal result?
The next step is usually to have an ultrasound examination. Ultrasound, which uses sound waves to take a picture of the fetus, can detect some types of serious birth defects. If the ultrasound doesn't provide an explanation for an abnormal test result, amniocentesis can be done to check for Down's syndrome and other chromosomal abnormalities. In this test, the doctor inserts a thin needle through the abdominal wall and into the uterus to withdraw a few teaspoons of amniotic fluid, which can be studied to see if the fetus's chromosomes are normal.
In conclusion, we must stress that only a few types of defects can be detected. In addition, a normal result does not guarantee that your baby will be normal.
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I have read and understand that this triple screen blood test is available at a charge of $150.00.
I DO DO NOT wish to have this test done.
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