Just went for my Oscar scan over the weekend Gynae measured the neck fold (dark line behind baby's neck) - i think this measurement combined with the blood test will give the risk factor of Down Syndrome. If it's thing like 0.2 to 1 cm should be ok. If it's thick like say 6cm, then might be of concern.
Saw my baby's sudden squirming and curling, so cute! Results were out and risk is low, so everything's ok! Paid about $400+ for both detailed scan and blood test. If I were to include her consultation fees and supplements for the 2nd trimester, then it all added up to $500+, gosh!