1st trimester test for birth defects availableby Heather WoolwinePublic Relations The thought plagues every woman at least once during the course of her pregnancy, if not immediately in those first few weeks: “Is there something wrong with my baby?” And while most babies are born healthy, the risk of having a child with a birth defect torture the minds and hearts of many parents. With the advent of better technology, especially in the last 20 years, parents now have many testing options to determine if a child is at risk for a birth defect. MUSC is the only fetal diagnostic center in the area to offer a new screening test for birth defects available in the first trimester of pregnancy. Simply called first trimester screening, the new test entered the commercial obstetrics market about a year ago and technicians require special certification to perform it. “We wanted to wait until the publication of the results of a national clinical trial involving the test before we offered this service,” said Sally Shields, MUSC genetic counselor. “This test is able to assess, prior to the 14th week of pregnancy, an 85 percent detection rate for Down syndrome and a 97 percent detection rate for Trisomy 18, a condition that results in severe mental retardation, physical defects and usually death shortly after birth.” The benefits of the new screening are the early time frame and a detection rate that is as good, if not better, than existing screening in the second trimester. The first trimester screening involves an ultrasound and a blood test. The ultrasound is used to measure the accumulation of fluid at the back of the baby’s neck called the nuchal translucency (NT). Increased fluid may indicate increased risk for chromosome abnormalities, congenital heart defects, and other genetic problems. The finger stick blood test measures two proteins found in the mother’s blood and those levels are combined with the NT measure and the mother’s age to determine risk for Down syndrome and Trisomy 18. If the patient is determined to be at an increased risk, then further diagnostic testing such as CVS (chorionic villus sampling) or amniocentesis may be offered. If the patient’s test does not present an increased risk, then it’s recommended the patient undergo an AFP (alpha-fetoprotein) screening in the second trimester to identify increased risks for open neural tube and abdominal wall defects. “But it’s important to remember that a normal screening test does not guarantee a normal baby, nor do abnormal screening test results definitely mean a baby with a birth defect,” Shields said. Obstetrics patients will still be able to forgo the first trimester screening if they desire and wait to have the second trimester quad test, which detects risk of spina bifida, Down syndrome, and Trisomy 18. Any patient over age 35 is always offered the more invasive methods of testing, like the CVS and amniocentesis, prior to the screening process. “All of the decisions related to invasive testing or any screenings are solely the patient’s discretion,” Shields said. “Our job is to make sure that our mothers know what all of their options are and that those options have been explained fully to our patients.” For more information about screening or diagnostic testing, call the MUSC Prenatal Wellness Center at 876-1200 or MUSC Health Connection at 792-1414. Friday, July 9, 2004
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