Genetic testing of a fetus offered for pregnant women

Genetic testing of a fetus offered for pregnant women

If you could know whether your unborn child was going to be born with a genetic defect, would you want that information? That is the basis of a quad test, offered to every pregnant woman, the first in a series of detection tools to determine if something is off with the fetus.

In part one of this three part series on genetic selection, 7News looks into how this test works and the conflict between nature and science.

When Melanie and Rick Sarro of Lake Charles decided to start a family later in life, they knew it carried a risk for pregnancy problems, but that did not deter their plans.  "We knew that we wanted to have children and that we were gonna have to not waste any time to do it," said Melanie.

Before the Sarros celebrated their third anniversary, Zachary was here and baby number two was on the way. "The pregnancy went very smoothly, it was uneventful," said Rick, "so it was a joyous event for both of them."

Because of Melanie's age, 37, her doctor offered a standard quad test, something she did.

Dr. Marshall St. Amant is the Director of Maternal Fetal Medicine at Woman's Hospital in Baton Rouge and his team of physicians travels to Lake Charles a few times a week to treat local women with high risk pregnancies.  He says a simple blood test can show a woman's risk for genetic defects.  "It never tells you for sure that the baby has a problem or does not have the problem you're looking for," he said, "it just says the risk is greater than or less than her predetermined risk by her age."

If the quad test does show that the mother is at risk of having a child with a genetic abnormality, then an amniocentesis is offered under the guidance of ultrasound technology with a thin needle. "The fluid is removed over a period of a couple of minutes and then it's sent to a laboratory for a very specialized analysis," said Dr. St. Amant.

Amniocentesis is the gold standard for diagnosing genetic disorders, analyzing every chromosome. "It will identify any numerical abnormality of the chromosomes, being a whole extra copy of a chromosome. It will also identify broken chromosomes," said Dr. St. Amant.

Defects are reported on a caryotype with nearly 100 percent accuracy.

The most common findings are on chromosome 18, known as Edwards syndrome and on 21, Down syndrome. "The patient would be offered the ability to continue the pregnancy," said Dr. St. Amant, "a secondary alternative would be the patient would be offered the ability to end the pregnancy."

When babies test positive for a genetic disorder, the termination rate is anywhere from 10 to 90 percent. It is a decision parents make after genetic counseling and advice from family members, even church leaders. "Genetics are personal choices," said Dr. St. Amant, "what people do with that information is up to them. So, we offer it to all patients and if they have an interest in it, we proceed."

That information is not always something parents-to-be want to know, especially in the conservative South.

The Sarros only did the quad test, showing a slight risk for Down syndrome, a condition Carter was diagnosed with at birth. "If I had to do it all over again, I probably would not have done the test," said Melanie, "just because I was so freaked out and scared the remainder of my pregnancy and it wouldn't have changed anything."

Yet many families want to know what is happening in utero, using the science to prepare for a child with challenges or keep that from becoming a reality.

Tune in for Tuesday night's special report on how in vitro fertilization is being used to transfer only non-diseased embryos into patients.

Click here to learn more about the maternal fetal medicine department at Woman's Hospital, that partners with Lake Charles Memorial Hospital for Women and Women & Children's Hospital to treat women in Southwest Louisiana.

This special report is part of a three part series on genetic testing.  Links to the two related pieces are below:
*Could embryonic screenings eliminate diseases?
*Investigating 90% termination rate for Down syndrome fetuses

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