I had a Nt thickness of 6mm and my bloods came back with a similar result. We had a CVS after speaking to the genetic councelor. My risk was 1:20 for downs and !:39 for Turner syndrome.
The local anaesthetic was the painful bit and because I was already run down from worry, I got very sick after it. I felt as though I had done 100 sit ups without training for it.
Fortunately for us, our FISH results came back normal and then we got our final results last Thursday and they were fine too. Now i have to have an u/s at 16 weeks and at 20 weeks to check for heart defects and to make sure the fluid has gone down at the back of the neck.
I guess it depends on what you want to do if the end results arent so good. If you would continue the pregnancy regardless of whether it has any abnomalities, dont have the test. However if you wouldnt continue and would opt for termination, then by all means do it. Its up to you. It is a scary process, but one that you have to decide on. Good luck.
Melissa