Got my letter this morning... Its dating mid january- i'll be 15 weeks. From my understanding, the NT scan for downs is supposed to be done between 11-14 weeks, after 14 weeks any sign of thickness or excess fluid will be absorbed and can go undetected on ultrasounds after that time. Also on my letter it stated if I have had a scan making me 8weeks or more, I may only require a detailed scan...??? WTF. Thanks NHS, thanks alot. I'll go for a private one at 12 weeks I think.