Why the test is done:
To screen for Down Syndrome, heart abnormalities as well as other anomalies.
How the test is done:
An ultrasound is done between weeks 11-14 to measure the translucent area in the skin on the back of your baby’s neck, known as the nuchal fold.
When the test is done:
Usually between 11-14 weeks gestation (from LMP).
How the results are given:
Usually as positive or negative, with about a 5% false positive rate.
Risks involved:
There is no risk to the test itself. Though it may be difficult to understand the results. This is a screening exam, used to help you understand your risk of genetic complications with your pregnancy. So you come into your pregnancy with a certain amount of risk of Down Syndrome. This screening test can alter the risk assessment. For example at 35 I have a 1 in 270 risk of having a baby with Down Syndrome. If my nuchal fold screening shows an average size fold, the risk is the same. If the fold is thinner my risk drops, but if it is thicker my risk may increase. This is where the recommendation for further genetic testing may come in.
Alternatives:
You can use more invasive testing like amniocentesis or chorionic villus sampling (CVS), but these run added risks to the pregnancy, though are more accurate.
Where do you go from here?
If the nuchal fold translucency is positive, you may be advised to go for more invasive testing like amniocentesis or chorionic villus sampling (CVS).
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