The Triple Screen measures three substances in the mother's blood. Based on the results of these three parameters a probability is calculated for the risk of Down's Syndrome and/or a neural tube defect. Please note that the triple test measures alpha?fetoprotein human chorionic gonadotropin (hCG) and estriol. These hormones are primarily produced by the placenta. Levels of hCG are higher than normal in most pregnancies if the fetus has Down's syndrome. Estriol levels are lower than normal in most pregnancies in a fetus with Down's syndrome. Therefore, by combining these three tests we can calculate the likelihood of Down's syndrome. A low triple screen test is used in conjunction with maternal age to predict the risk for Down's syndrome. Ultrasound and Amniocentesis are generally recommended if the risk approaches one out of 270 or if the calculation indicates an abnormal risk. The exact causes of neural tube defects are not known but are thought to be multi?factorial. In the United States approximately 1 out of every 1,000 pregnancies results in a neural tube defect and APPROXIMATELY 95% OF ALL CASES OCCUR IN COUPLES WHO DO NOT HAVE ANY PREVIOUS OR PERSONAL FAMILY HISTORY OF NEURAL TUBE DEFECTS. There is an increased risk of neural tube defect if a couple had a previous child with a neural tube defect or has a close relative who had a neural tube defect. The triple screen test must be performed between 15 and 18 weeks of pregnancy. Therefore, it is a "timed test" and must be done at a certain time during the pregnancy, (15 to 18 weeks). The general risk of having a live baby with Down's syndrome is:
Trisorm 21 results when there is an additional chromosome #21. If you have further questions or concerns about this screening test please discuss them with your provider at your next visit or call our office at 770-924-6255, in Woodstock, 770-844-0546, in Cumming, or 770-475-1666 in Alpharetta.
