Before we talk about the available testing options, we need to define the difference between the two categories of available tests: screening tests vs. diagnostic tests.
A screening test gives us information on the risk of a pregnancy having a specific problem.
Another way to think about it is, “What are the chances/odds that a problem may exist?” While an abnormal result on a screening test may be concerning, it only signals a potential problem which may require further testing to follow up. In order to have a definitive answer it is necessary to perform a diagnostic test. This type of test will let you know 100% if there is an abnormality, but is an invasive test that requires a procedure to collect either amniotic fluid or a small sample of cells from the placenta.
We offer screening and diagnostic testing to all our patients. This is a personal decision that you and your family may want to consider. Some women will want to do screening tests initially, because it is not invasive (there is no risk to the pregnancy). If this result shows that your pregnancy is at increased risk, we will refer you to consult with a genetics team for further diagnostic testing options. Other women, especially those at higher risk including those over the age of 35 or who have had a history of a genetic problem in a previous pregnancy, may want a diagnostic test done initially. It is also acceptable for you not to undergo any genetic screening, if you choose.