Down’s Syndrome Screening Using Ultrasound

September 15, 2006

OBGYN.net Conference CoverageFrom AIUM 44th Conference held in San Francisco, California - April, 2000

Terry DuBose, M.S.: "We’re at the 44th Annual AIUM Conference in San Francisco with Dr. Greggory DeVore who works in the Fetal Diagnostic Center of Pasadena and has an appointment with NIH. He can tell us something about Down syndrome screening using ultrasound in a population that may want to avoid amniocentesis."

Dr. Greggory DeVore: "Let me review the basics of a talk we gave at this meeting this year. As you know, there are women who are at risk for Down syndrome based upon their age of thirty-five or higher or younger women who have been screened with blood tests and told the risk for Down syndrome is high. We found that in over 50% of women over thirty-five, a large majority of women, who had a blood test that was abnormal, often do not want amniocentesis. They want to avoid it because of its potential complication rates and so a non-invasive way of addressing this issue is the use of ultrasound to look at the fetus to determine whether or not the fetus has markers to suggest Down syndrome. In our presentation this week at the AIUM meeting, we presented data, which demonstrated that we could have a detection rate as high as 91% for Down syndrome using ultrasound and looking for specific markers in the fetus. That detection rate can vary from 91% to 75% or 60% depending upon the skill of the ultrasound person doing the ultrasound. We gave the physicians a list of things to look for that would allow them to have that range of detection; it’s based upon experience and skill using ultrasound machines. Now the benefit of this approach is that we can decrease the amniocentesis rate by as much as 87% and so that translates into a lot of fetuses that would otherwise be lost for amniocentesis, and the key thing is that it really depends upon the needs of the patient. If the patient says - I need to know, I would not continue this pregnancy if I had Down syndrome baby, perhaps she needs an amniocentesis. The patient who says for religious reasons, personal reasons, or she’s spent $50,000 on vitro fertilization, she wouldn’t necessarily terminate the pregnancy for Down syndrome, then perhaps this is a very good alternative because we avoid amnios in fetuses who don’t have any markers; we would then do amnios in those who do. So it gives the patient a much broader range of choice, and we find that this is a very popular request throughout the country."

Terry DuBose, M.S.: "Does the success depend on when in the pregnancy it’s done?"

Dr. Greggory DeVore: "Yes it does, it depends upon if it’s done in the second trimester. Our genetic ultrasound that we do is done from 16 to 22 weeks. The best time is about 17 weeks."

Terry DuBose, M.S.: "Why would a woman who isn’t going to terminate want to do this?"

Dr. Greggory DeVore: "This is a very good question, as you may be aware of, Down syndrome fetuses or children with Down syndrome have a very high incidence of congenital heart disease that can be very serious. Sometimes a woman, for example, may have a child who has Down syndrome with a heart defect, she goes to a small community hospital, and while the Down syndrome may be obvious or may not be obvious, the heart defect can be very significant for the child. So by knowing about that, you can offer immediate newborn care which would be different. Secondly, Down’s fetuses have a higher risk for growth retardation, which is a growth abnormality where you don’t grow as well. It’s been my position in the 30% of women who have Down’s fetuses who continue the pregnancy to treat them as high risk because I want to have the healthiest Down’s baby for them. So if I identify Down’s and know it’s there I know they have problems during the pregnancy, I can do things that will make the outcome better. My position is I want you to have the healthiest Down’s child because it’s going to have some problems so why encumber it with other problems if you can avoid it."

Terry DuBose, M.S.: "Right, that’s good. Thanks, Dr. DeVore."

Dr. Greggory DeVore: "You’re welcome."