With 96.6% accuracy, it's not much better than the first trimester screen and probably a lot more expensive...
For the first trimester (NT) screen, you get the most accurate results if you do the finger prick at 10 weeks and the ultrasound at 12 weeks. I guess there are soft markers you can look for that the clinic may or may not look for depending on their protocol. These include the presence of the nasal bone and the angle of the palate relative to the forehead. (Had a miscarriage after my NT screen was abnormal, so I researched it a lot.)
This video lecture is really good.
https://www.fetalmedicine.com/fmf/o...This=true&TB_iframe=true&height=370&width=350