I would say that it is definitely possible to suspect CAH from a sonogram. When I was pregnant with the twins, I had so many sonograms. Each time the staff doing the sonogram said "both girls" (and yes! they were looking at the genital area to determine that! there was never a comment that either baby could be a boy!). I guess they were just looking to see if testicles were present and none were. They gave us quite a few of the sonogram pictures, and my husband & I could see a structure that resembled a small penis in a few of the sonogram pictures, but we figured the "trained staff" knew what they were talking about in that they were both girls. No one ever suspected something was wrong throughout the whole pregnancy and we were at a well-known teaching hospital. Then at birth, well you all know how it goes in the several days of waiting to determine the sex of your child. I still have those sonogram pictures and am willing to mail a photocopy of them to "our legitimate family members here" - seeing those sonograms will show you that the ambiguous genitalia definitely may show up on a sonogram. However, we are in the process of moving & the sonogram pictures are all packed up. I am the one whose twin daughter died in June 1999 due to an adrenal crisis, and oh how I cry when I look at those sonograms and think, if only then CAH had been diagnosed, maybe we'd have found a good endo & my daughter would still be alive.