NT Scan Tomorrow

We have our "NT Scan" tomorrow to test for Down Syndrome. I'm slightly nervous, but trying to stay positive. I know my odds go up with each year but as far as I know, chromosomal abnormalities don't run on either side of the family. I'm sure everything will be fine.
Here is an overview of the procedure:

Nuchal scan is performed between the 11th and 13th week of gestation, because the accuracy is best in this period. The scan is obtained with the fetus in sagittal section and a neutral position of the fetal head (neither hyperflexed nor extended, either of which can influence the nuchal translucency thickness). The fetal image is enlarged to fill 75% of the screen, and the maximum thickness is measured, from leading edge to leading edge. It is important to distinguish the nuchal lucency from the underlying amnionic membrane.
Normal thickness depends on the crown-rump length (CRL) of the fetus. Among those fetuses whose nuchal translucency exceeds the normal values, there is a relatively high risk of significant abnormality.

From what I've read, we want to see a nuchal thickness of less than 2.5mm.

Here is a link to a good definition of the test. Wish us luck tomorrow. :)

http://en.wikipedia.org/wiki/Nuchal_scan