The sequential screen has a 5% false positive rate meaning 1 out of 20 times a positive
screen for T21. If you screened positive, you are able to get the cell-free
fetal DNA
screen which has a sensitivity greater than 99%. As far as the abnormal PAPP-A, it can have a very small association with growth restriction. You will just need a 3rd trimester scan at about 32 wks to check fetal growth. Nothing to worry about. Ask your OB about the fetal DNA screen. It is just a blood draw from you.