A person’s risk for some genetic disorders may be calculated based upon the occurrence of those disorders in other family members. Also, for both disorders that have been linked to genealogy and those that have not yet been linked to genealogy there are times when an individual can be screened for genetic disorders. One of the times when genetic screening is available is during the first trimester of pregnancy.
The first trimester screen is a noninvasive test that consists of two parts. One portion of the test is a blood test and the other involves an ultrasound. The test identifies the risk of the fetus being born with Downs Syndrome, Trisomy 18, Trisomy 21, and a few specific cardiac disorders. This specific test has been in use for a few years but has only recently gained widespread acceptance as an accurate indicator of risk for those disorders.
If a woman chooses to undergo first trimester screening, it is very important that her doctor helps her to understand the test results when they arrive. If you were to receive a positive test result for one of the disorders without any guidance about interpreting that result, chances are that you would think that that means that your baby has the disorder. With this test though, that is not the case. A positive result indicates that there is a one in a hundred (or one in three hundred depending upon which disorder it is) chance of having the disorder. What a positive test result usually results in is further more specific testing to determine whether or not the baby actually has the disorder. It is also important to remember that the first trimester screening is a screening test and not an actual diagnostic test. Screening tests assess risk based upon a number of factors, whereas diagnostic tests look at a problem and figure out what is going on.
The first trimester screening is just one of the genetic testing tools that are available throughout the course of a pregnancy. Pregnant women should enlist the help of their health care provider and partner in deciding whether any or all of the tests that are offered are something that they want to do. There is a lot of information available about each of the tests so that couples can research the tests that have been recommended to them before making their decision.