Couldn't squeeze First Trimester Screen (FTS) in the discussion title box but that is what I am referring too!
Anyway, I will be doing this at 12 weeks. (I am a little over 10 weeks today) I found, somewhere on this forum, a really great link to www.fetal.com  that had a movie describing in terrific detail what is involved in the FTS and how results are calculated.
It refers to more than just the nuchal translucency as a physical marker in the sonogram portion of the screen.
Did your screens also look at the nasal bone and blood flow through the ductus venosus (an area of the heart) ??
Also implies that for women in our age group probabilities for (or not) trisomy 21, 18 and 13 are more accurate than younger women. That is, they are more likely to miss an abnormality in a 25 year old woman then they are in a 45 year old woman. I found this greatly reassuring. (I mean not for the 25 year olds - but you know what I'm saying!)
Did your doctors or genetic counselors talk to you about that??
I have a call into the place where I will have mine (Genetics and IVF Institute in Fairfax, VA) to find out their point of view on probabilities once all things are considered and if they check for the additional markers.
Please share anything you can about your FTS! Thanks!