Hi, I'm not quite sure of some of your terms so sorry if I don't give helpful info (qnatal test and MFM) but my dd's 12 week NT scan was flagged up at 3.5mm. As a heart defect can cause build up of fluid if it's not working properly she was given two detailed heart scans at 16 and 20 weeks, at the first they were pretty sure her heart was fine and just confirmed at the second when it was more developed. They only took about 10 minutes each. We never had any definitive testing but she was born 100% healthy in terms of heart, chromosomes etc, just with a pretty chunky neck which she's now grown into! There's no heart issues in our family so I can understand you have that additional concern it could be related but hopefully you're assured 3.5mm can mean nothing too. Hope you get some relieving news soon, such a scary time x
