No idea Aurora. I have always had bloods for HIV, HepB, Iron and a few others done at 9-10wks as routine and then the option of the scan at 12-13 wks for the NT screening (I have only had this done once) and then if the results from that scan are a bit off, then you will have the follow up ones after that normally. Depending on who does your scan they should be able to give the the ratio of downs risk then and there.