I had a 1/37 chance of
DS but my son doesn't have it. I opted for the amnio to get actual results rather than just a risk factor. His NT measurement was 4.1 I think & I looked at the CD over & over & found all the other measurements were lower so I think they must base it on the highest measurement they get.
That sonographer handled the situation very badly. Mine was very nice & pointed out that the measurement was high & that I should be prepared for the possibility of further testing. She spent over an hour doing the scan. She also told me that there were no other markers so he looked normal apart from the measurement.... but mine was done where they only do pregnancy scans so I guess they are used to dealing with this type of situation. She also gave me a 3D pic & a couple of normal ones as well as the CD to take home. I wish you'd been seen by someone as nice as her.
I hope it all goes well on Monday & the wait for the results goes as quickly as possible for you.