Hi ladies, my gynae suggested for me to opt out for blood test (harmony test/Oscar) test for down syndrome. She said blood test will not be the best choice because if the results show high risk for down syndrome, we will not know if both twins are high risk or just one (also which one). She suggested to scan for the thickness of the thick and nose bridge which is sufficient, but online research shows 80% accuracy for the scan compare to harmony test which is 90% over.
Any advice?