Get a CVS! I am 39 and was concerned about DS. I went last week out of state to get both the NT and CVS because CVS was not offered in my state. While it is an invasive test, it will provide info on chromosomes just like an amnio. If you are going to do this, you need to do so ASAP because the window for doing so will be closing soon and then you will have to wait for an amnio. I am not quite sure why they suggested that the next step to be another u/s, I would have thought that they would have recommended a CVS.
My NT was 1.5mm and so things look like they will probably be okay, but I wanted to be as close to 100% sure that the baby would not have DS. I am now waiting for the results 10days-2weeks.
If I were you, I would also request a FISH analysis and they can get the results sooner in 24-48 hours.
With regards to the procedure, make sure that you have someone who does this all of the time. I went to Swedish in Seattle. Most of my time was spent with a genetic counselor. The actual CVS was so quick. I am a HUGE baby when it comes to needles, but I did it. So, it was not comfortable, but he was so experienced and the placenta was in the right area that it was easy for him to get the sample he needed in less than 1 minute.
He was in the room with me probably for a total of 7 minutes including introductions, prep and the procedure.
With regards to the risks, which everyone is concerned about, see the latest stats at http://www.acog.org/from_home/publications/press_releases...
In any case, you will have to weigh the risk vs. benefit of actually knowing. Since your risk for having a DS are substantially high due to your age and test results, the risk of CVS may not seem nearly as high.
I would definitely act now though as I almost fell through the cracks with my practioners and insurance. If nothing else, get the ball rolling. I wanted to go a week earlier, but there was noone doing the procedures that week. So, get an appt. set up and then if you change your mind, you can do so, but I don't want you to miss the window of opportunity and then have to wait for amnio if that is what you will ultimately end up doing. Certainly, if you have any thoughts of terminating, I would absolutely insist that you should do a CVS and not rely upon u/s.
Best wishes.
P.S. I had no complications other than I was a bit sore right afterwards, but I went to my hotel room and rested. You could hardly tell where the needle was by that night and I had a rash reaction to the bandaid as you could see where the bandaid was a day after I removed it. No bleeding, no major cramping, no infection.