Its probably a bit premature but I would probably put a complaint in about the sonographer. Even if your at a higher risk it might be 1:200 or 1:100 or something the stats the sonographer gave you is 1:10 which is probably bull S and contributed to unneccessary anxiety. As far as I am concerned it wasn't his/her area to say that to you. Obviously now you need to wait for the BT and hopefully that reassures you that bub is ok. Even if the correct NT was 2.32mm that alone would not give you a risk of 1 in 10 on its own without the BT.