Hello, I am 19 weeks 3 days pregnant. My doctor noticed today one of my baby s femur bones is slightly bowed, and .07 cm shorter than the other. Can you please tell me, the best and most accurate test for genetic abnormalities that this can be linked to? I had screening (blood, nasal, and nuchal fold) for trisomy 21, spinal bifida which came back negative. This abnormality wasn t present in last month s scan, and all other bones are correct length. What is your opinion..