Ahh, I know what you mean Sophie. The test we're having done tests for Turners (X), Klinefelter (XXY), Triple X (XXX) and XYY Syndrome because these types of disorders (Specifically Turners) do run in my family and of those 4, Turners poses the most risk as it carries the risk of miscarriage in the second Trimester or heart defects. The way the Dr explained it was if it the baby came back as XX or XY (simply girl or boy) it basically ruled out Sex-linked traits like the ones I listed. If it weren't for that, we would have just done the normal Quad or Serum screen that tests for just the Trisomies