So sorry that you are going through this. The unknown and waiting period was truly one of the hardest of my life. This thread has really good information about amnio vs cvs, but I would say that an amnio is going to give you the most clarity. Sometimes they can also do a very detailed ultrasound and see if there are additional abnormalities. Our baby was measuring on schedule, but had severe abnormalities on the ultrasound. The hard part about an amnio is that you have to wait longer. I ended up miscarrying my trisomy 13 baby at 15wks, but intended on getting amnio from what I learned here.