Not 100% sure but don't you have ablood test done at the same time you have the U/s scan at 12 weeks to look for Downs? I know when I had a 12 week ultrasound done with my 2nd my GP would only send me for a downs scan even though I wasn't a risk. She also said there is a blood test that is done but I said I didn't think it was worth it as I only wanted the u/s to check baby was developing well.

Have you googled it?