There are several options available for pregnant women regarding genetic testing. Some methods require a simple blood test, while others are more invasive and associated with some risk. Genetic testing cannot detect the majority of birth defects that could affect a fetus, and no test can guarantee a perfect baby.
The following is a brief summary of what testing is available along with some of the advantages and disadvantages. These tests are all considered optional; however, approximately 90% of patients pursue testing. Keep in mind, there are noninvasive tests which are only screening tests and invasive tests which determine a diagnosis.
Currently, the standard of prenatal care is to offer second-trimester testing. The American College of Ob/Gyn feels first trimester screening for Down syndrome is an option. Until recently, no testing was available to detect chromosomal abnormalities like Down syndrome in the first trimester that was not invasive. Currently, there are three options.
The advantage of the First Trimester Screen is that it is noninvasive and offers information about DS and Trisomy 18 as early as 12 to 14 weeks. Because it is not as accurate at detecting chromosomal problems as the Integrated Screen, this screen would be recommended to patients who want the earliest possible information to consider a Chorionic Villus Sampling.
For our low-risk patients, we recommend the Integrated Screen as it has the highest detection rate for chromosome abnormalities and is noninvasive.
NIPD – Noninvasive Prenatal Diagnosis: The MaterniT21 PLUS laboratory-developed test is a non-invasive blood test that is available for women with increased risk indicators for fetal chromosome variations at 10 weeks of pregnancy and beyond. This test detects an increased amount of chromosomal 21, 18, 13 material that is circulating in maternal blood. The increased risk factors include one or more of the following:
Advanced maternal age,
Positive serum screening test,
Fetal Ultrasoundabnormality suggestive aneuploidy,
and/or Personal/family history of chromosomal abnormalities.
The following tests are routinely offered in the second trimester:
Quad Screen: This is a noninvasive blood test offered between 16 and 20 weeks which screens DS, NTDs, and trisomy 18. The test will detect approximately 80% of babies with DS and 80-90% of babies with NTDs. The detection rate is lower than the Integrated Screen and therefore is recommended for patients who present for care in the second trimester.
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