I have just answered this question in rainbowbright's first tri thread so I shall cut and paste my answer here:
I had one at 12 + 5 due to a 'high risk' NT scan result. The doc who did it was very reassuring. My OB recommended him as the doc who does the most CVS tests in the area, and his clinic's risk of miscarriage were only 0.01 - 0.5%. When you read statistics online, they will tell you that the risks are much higher, but often this is because they are done much earlier in pregnancy, and usually to high risk pregnancies, so the chances are many of these may have miscarried alone anyway. The doc explained that in his experience, the risk is lower than that of an amnio because you don't go near the amniotic sac, only the placenta. he said that the placenta is like a sponge - so imagine if you stick a needle in a sponge, it springs right back again, no damage done.
I was dreading the procedure and was really scared - I am a complete wuss and hate needles. However the most painful bit was the local anesthetic injection, and after that it was painless. They scanned the baby throughout so we could see her moving, and you could see the needle going into the placenta (I say this, but actually I had my eyes closed the whole time so actually it was my OH who saw all this!) I just squeezed my OH's hand and the nurse was telling me to breathe in and out slowly, so I just concentrated on her and then it was over in like 5 minutes... the anticipation is much worse than the reality!! In fact I had a blood test afterwards and that hurt more than the CVS!!!
After it was over (and because I had had my eyes closed througout!) they then scanned the baby again so that I could see her moving, and showed me her heartbeat on screen. I then went and lay down in an adjoining room for 30 mins and then they took me back in and re-scanned, and showed the heartbeat again. This was hugely reassuring. and the doc showed us all the body parts and gave me some pics to take away.
I then went home and went on bedrest for 24hours. I was told - no exercise/heavy lifting/sex for 1 week. I think some spotting and/or cramping can be normal afterwards, but I had neither, apart from slight cramping for the first hour after the procedure - but they told me to expect this (the nurse explained it would ache just like your arm does when you have an injection in it) so I wasn't worried by it.
They phoned with the preliminary results (where they test the five chromosomes that have the highest risk of abnormality - ie. the two sex chromosomes and those responsible for Down's, Patau's and Edward's) back in three days and all were thankfully negative. This was a massive relief and a HUGE weight off my mind. The full results came back two weeks later (also by phone), all also negative. I am SO pleased I had it done, I would have been a complete nervous wreck had I waited for an amnio or not done anything.
Good luck, I am sure you will be fine x
