Isn't that an ultrasound to check for down's syndrome. They do it fairly early, however, I don't think at that point you'll be able to tell the sex of the baby.
It is done between 11-14 weeks,and I have read that from medical journals that at 12 weeks, there is about a 90% correct rate of knowing the sex. It is done for Down's. It used to be for those 35 and over, but it is now recomended for ALL women.
This test is usually done in between 12-15 weeks I think. I had mine done at 13 weeks and was told that I was probably having a girl but that they couldn't confirm it 100%. They said it was about an 80% chance.
Well, I had a girl!!
its a little early sice you primarily have the test between 11 and 13 weeks however you will find out at your anatomy scan from 18 to 20 weeks goodluck on the boy i am in the same boat all girls for me but not pregnant at the moment.