Down Syndrome now Detectable at 11 Weeks
Nov 10, 2005 - 8:01:38 PM
A new study from Columbia University Medical Center researchers at NewYork-Presbyterian Hospital/Columbia of more than 38,000 pregnant women at 15 U.S. centers demonstrates the high accuracy of non-invasive screening for Down syndrome (also known as trisomy 21) in the first trimester of pregnancy, at 11 weeks. The findings are a significant advantage over the current standard screening, a blood test performed in the second trimester of pregnancy. Published this week in the New England Journal of Medicine (Nov. 10, 2005 issue), the study is known as the FASTER trial (First and Second Trimester Evaluation of Risk). It was funded by a $13 million grant from the National Institutes of Health and the National Institute of Child Health and Human Development one of the largest ever grants for an obstetrical study.
The new screening approach uses a blood test that analyzes the level of a protein and hormone in the mother's blood, combined with an ultrasound or sonogram picture of the thickness of skin on the back of the baby's neck (known as the nuchal translucency or NT). Results are available within five days, often before starting the second trimester of pregnancy. This combination approach determines the odds that the baby might have Down syndrome, allowing pregnant women the option of prenatal diagnosis for Down syndrome and other chromosomal abnormalities within the first trimester or pregnancy. The researchers found higher detection 87 percent in the first trimester compared to the best second trimester screening method 81 percent detection. Results with this new combination screening approach in the first trimester are a significant advantage over the current standard screening test.
First-trimester screening was performed on 38,167 patients; 117 were found to have a fetus with Down syndrome. If a positive result was found via screening, the woman was given the option to have the finding confirmed with a diagnostic exam: chorionic villus sampling (CVS) or amniocentesis. Both tests carry risks of complication leading to miscarriage.
Down syndrome is one of the leading causes of mental retardation and birth defects, found in one in 660 pregnancies. Persons with this condition have distinct physical features and commonly have certain birth defects and medical problems. Any woman can have a baby with Down syndrome, regardless of her age, race, health, economic status or family history. For this reason, most pregnant women undergo testing to determine their potential to have a baby with this syndrome.
"These results will undoubtedly change national practice all pregnant women should have the option of early screening for Down syndrome in their first trimester," said Mary E. D'Alton, M.D., principal investigator of the study. She is Chair of the Department of Obstetrics and Gynecology at Columbia University College of Physicians and Surgeons, and Chief of Obstetrics and Gynecology at NewYork-Presbyterian Hospital/Columbia. "Down syndrome screenings based on either maternal age alone, or an ultrasound or sonogram alone, are no longer justified protocols."
Dr. D'Alton and the research team believe that the new screening method should only be administered by qualified, trained physicians. Dr. D'Alton and other experts working with the Society of Maternal Fetal Medicine have recently formed the Maternal Fetal Medicine Foundation to facilitate physician training and quality review for the screening. So far 1,600 physicians and sonographers nationwide have undergone training, and more are scheduled. Information about the training and quality review program can be found at http://www.MFMF.org.
Women seeking this early screening should seek healthcare professionals with appropriate ultrasound training and who participate in ongoing quality monitoring programs. Programs should provide sufficient information and resources for counseling regarding the different screening options and limitations of these tests. Additionally, the services should provide access to an appropriate diagnostic test when the screening test is positive.
"This study was a wonderfully collaborative effort between researchers, including four leading Obstetrics and Gynecology centers in New York City. This incredible achievement would not have been possible without the hard work of the 15 centers that comprised the FASTER Research Consortium and the 38,167 women who participated in this clinical trial," said Dr. D'Alton.
The term 'Down's syndrome' was first used in 1961 by the editor of The Lancet. Of the inborn disorders that affect intellectual capacity, Down syndrome is the most prevalent and best studied
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