There is a difference between prenatal screening and prenatal diagnosis. Most women are offered prenatal screening as a matter of routine during pregnancy, and many are unaware that they can refuse such screening. Prenatal screening and diagnosis is a perceived 'good' in that it is promoted as being in the best interests of women to know about the health of their unborn children, yet it is clear that many women experience great distress when advised of even a low risk of potential abnormalities, and others experience enormous pressure toward termination, told that this option is the most compassionate one for their child.
It is important to understand the purpose of prenatal screening and what the results may mean in terms of the requirements of further testing, or potential decision making about your pregnancy. The following information and links are designed to accurately and fully inform you not only about the tests and processes themselves, but also about what to expect afterward.
Nuchal ("new-kul") translucency screeening
This is the most common and routinely offered test offered to pregnant women in the first trimester of pregnancy. The test is non-invasive and performed via ultrasound. The ultrasound is used to measure the thickness of the fluid buildup at the back of the baby's neck. If this area is thicker than normal, it can be an indicator that your baby is higher risk of having Down's Syndrome, Trisomy 18, or heart problems. Remember, that this is an indicator only. The test is for screening, not diagnosing.
This ultrasound is usually undertaken in conjunction with a blood test called Maternal Serum Screening (MSS). Even if both of your tests show a risk for congenital abnormality in your baby, this does not mean your baby has any problems. In order to find out for sure about your baby's health, you would be required to undergo further diagnostic testing, usually in for the form of amniocentesis or Chorionic Villus Sampling (CVS).
Common diagnostic tests
Chorionic Villus Sampling