Hi, first take a deep breath ....the cyst in the choriod plexus is just a possiblity not a definite result for down syndrome and from what I remember quite common. I had identical twins and one of them had that and the other one didn't. It usually goes away on its own. I don't even think he had it anymore in the 3rd trimester. Had any previous ultrasound been irregular, the shape of the neck, spine and head? Also, go with your gut and do what you think is best. Amniosyntesis is the only 100% accurate test for down syndrome and other genetic innacuracies. Everything else just that a possiblity a maybe. Ask yourself If a positive result would affect the outcome then have it done and honestly the procedure is very short ( I did not have it done, ever) but I went with a close friend because she had to know and the result would affect the outcome. she is over 35 her chances of down syndrome are high risk for her age. In the end everything was fine her daughter is a healthy normal 2 year old. I wish you the best of luck and have faith and hope that everything will be okay.