Just wanting to pick someone's brain if anyone knows about the need for a special cardiac scan. I've had my 12 week scan at FMC and my sonographer recommended a cardiac scan at 20 weeks because the nt measurement was 2.6 mm. This is despite my combined risk for the trisomies being very small, and I also had the Harmony test which apparently reduces this further. I have booked in for the extra scan but am now wondering if this is over the top cautiousness as NHS doctors seem to consider 3.5mm to be the cut off for further investigation. I don't really want to pay £250 and have an extra scan for the sake of it, and it's booked the same day as my 20 week scan. Any thoughts appreciated, thanks!