19 weeks pregnat blood came back negative but they can see babys bone in nose does it always mean down syndrome?

Not Down's: The blood test is the gold standard for testing. I would believe that 10 times more than an indistinct shadow on a 19 week ultrasound. There are lots of false positives (meaning a condition is suspected but ends up not being true) with us screening. That's why it is just a screening. If you then have a positive screen, you move ahead to the gold standard test - in this case the blood work or amnio.