Safer Tests For Chromosomal Disorders
Traditional tests for chromosomal disorders
Amniocentesis and chrionic villus sampling are two invasive tests that analyze a fetus for Down syndrome, each posing a small risk of causing a pregnancy to miscarry. However, "for women at age 35 years old, the risk of having a baby with chromosomal disorders only increases a 1/2 percent," shares Hal C. Danzer, M.D., co-founder and partner of the Southern California Reproductive Center, "so unless women are 40 years or older, I suggest testing with alternative methods before opting for an amnio." So, what are your options when seeking out your risks of chromosomal disorders?
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Non-invasive blood tests during pregnancy
Sequenom Inc. last fall released a blood test that detects Down syndrome, which is only available in 20 cities in the U.S. However, two studies published in 2012 state that another blood test – developed by Aria Diagnostics – can reveal markers for Down syndrome and Edwards syndrome, another genetic disorder known to cause fatal birth defects, when scanned before 20 weeks gestation. One study was conducted by the University of London and University College London and detected all Down syndrome cases and 98 percent of Edwards syndrome cases, while the study conducted by Aria Diagnostic researchers correctly identified 44 of the 167 cases.
First trimester nuchal fold scan
Also known as the nuchal translucency screening test or NT, it is a prenatal test that helps your physician measure your future baby's risk for Down syndrome and other chromosomal disorders. Using an ultrasound to measure the translucent tissue in the back of the fetus' neck between 11 and 14 weeks gestation, it gives you a clue into whether or not you may want to consider an amnio or chorionic villus sampling. "A nuchal fold test is 93 percent accurate at ruling out Down syndrome," explains Dr. Danzer, and is non-invasive.
So, although these tests can help measure your risk of Down syndrome and other chromosomal disorders during pregnancy, are they a strong alternative to an amnio or chorionic villus sampling? "At this point in time I would use these tests as an early "double check," suggests Dr. Mary Hinckley, a reproductive endocrinologist at Reproductive Science Center of the Bay Area. "If the tests come back abnormal, consider more invasive testing earlier. However, if you would not terminate a pregnancy, then consider these tests as an alternative to an invasive test that might otherwise increase your risk of miscarriage of a healthy baby." And, especially true for women between ages 35 and 40 years old, you can have the peace of mind knowing that amnio isn't the only option.