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Fetal testing: everything you need to know

The umbrella category of “fetal testing” includes a number of tests used independently, or in conjunction with each other, that serve to screen for or diagnose chromosomal or other disorders. Every testing option has its positives and negatives, so it’s important to choose wisely which fetal testing options you would like to explore.

First Trimester Tests

  • First trimester screen: This test combines a Nuchal Translucency ultrasound with a blood screen for two substances found in the body during pregnancy, human chorionic gonadotropin (hCG) and Pregnancy-associated plasma protein A (PAPP-A). The Nuchal Translucency test looks for the amount of fluid at the back of Baby’s neck, an excess of which could indicate a risk for chromosomal abnormality. Too little, or too much of either hCG or PAPP-A also indicates a risk. These tests are considered together, and the odds of a chromosomal abnormality are calculated based upon the findings. If your odds exceed 1/230, the test is considered “positive”, and your health care provider will probably recommend you for further testing. The First Trimester Screen is usually performed between weeks 11 and 13.
  • Chorionic villus sampling: Also known as CVS, chorionic villus sampling involves extracting some chorionic villi cells from the placenta through a cervical catheter, and testing them to determine whether or not there is a chromosomal abnormality. The CVS is a diagnostic test, meaning its results are far more accurate and conclusive than the First Trimester Screen. However, according to the Mayo Clinic, chorionic villus sampling carries about a 1% risk of miscarriage, and is not 100% diagnostic, so most women who elect to undergo this procedure will do so at a healthcare provider’s recommendation because of age or family history. Chorionic villus sampling is available usually between weeks 10 and 13.
  • Cell-free fetal DNA testing (Non-invasive prenatal testing): A new and technologically advanced test, cell-free fetal DNA testing searches for fetal aneuploidy (abnormal number of chromosomes) without any risk to you or your baby. The test searches for fetal DNA in your own blood, and is then sequenced and analyzed for the presence of any chromosomal abnormalities. The American College of Obstetricians and Gynecologists recommends that any woman at an elevated risk of having a baby with aneuploidy (advanced maternal age, previous positive screen, personal or family history of chromosomal abnormalities) be offered non-invasive prenatal testing.

Second Trimester Tests

  • Triple screen test: The Triple Screen Test is a blood test that examines the levels of three substances found in a woman’s blood; alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and estriol. Higher than normal AFP generally means that prior calculations of Baby’s due date were wrong, but can also indicate a heightened risk for a neural tube defect like spina bifida. Low levels of AFP, and either high or low levels of hCG or estriol can indicate an elevated risk for a chromosomal abnormality like Down syndrome (Trisomy-21) or Edwards Syndrome (Trisomy-18). The Triple Screen Test cannot diagnose a disorder, but after comparing the blood test results to a woman’s risk factors, healthcare providers may make a recommendation for further testing, like an amniocentesis. The Triple Screen Test is available between weeks 15 and 20.
  • Quadruple screen test: Increasingly more popular, the Quad Screen tests not just the three substances examined in the Triple Screen, but a fourth, a hormone known as Inhibin-A, as well. High levels of Inhibin-A suggest a heightened risk for Down syndrome. The Quadruple Screen is usually performed between weeks 16 and 18.
  • Amniocentesis: Highly accurate but not without risk, an amniocentesis is frequently recommended by healthcare providers if a previous screening test indicated some risk factors for a chromosomal abnormality or other developmental disorder, there is a family history of a disorder, or if you are 35 years or older. An amniocentesis involves inserting a needle through your stomach and womb, and extracting some amniotic fluid to be tested. The extracted fluid will be sent to the laboratory and analyzed, and has the ability to communicate not just chromosomal abnormalities, but neural tube defects and genetic disorders as well. Amniocentesis entails about a 1 in 400 risk of miscarriage, and a slight risk of infection, so it’s important for every mom-to-be to weigh the risks and rewards before undergoing one. Amniocentesis is available between weeks 14 and 20.

Another important consideration is cost. Where you go to get your test or procedure can make a tremendous difference in how much you pay.  It is common for costs to vary as much as 300- 500% for the same procedure depending on where you receive your treatment.  Fetal testing can run anywhere between $50 and $200. To make sure you’re paying a fair price (the price you should reasonably pay) for your testing, check out Ovia’s price transparency partner Healthcare Bluebook. Their free pricing tool helps patients make smarter and more informed decisions about important medical procedures.

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Sources
  • Amy Swanson, Amy J. Sehnert, Sucheta Bhatt. “Non-invasive Prenatal Testing: Technologies, Clinical Assays and Implementation Strategies for Women’s Healthcare Practitioners.” Curr Genet Med Rep. 1(2): 113-121. Web. 6/13/2015.
  • Mayo Clinic Staff. “Prenatal testing: is it right for you?” Mayo Clinic. Mayo Clinic, 8/4/2015. Web.
  • Mayo Clinic Staff. “Chorionic Villus Sampling.” Mayo Clinic. Mayo Clinic, 10/17/2015. Web.
  • C White. “Chorionic villus sampling.” U.S National Library of Medicine. MedlinePlus, 11/16/2014. Web.

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