Sex from non-crotch u/s pic? (also posted on May board)

noycela

I also posted this on the May board:  We had our a/s yesterday (it went great!).  We didn't want to find out the sex, and the tech was great about keeping it a secret.  Well, last night DH was showing our friend one of the ultrasound pics -- a profile shot of the whole baby with his/her little legs bent up.  Our friend is a chiropractor and works with babies, so he's very familiar with human/baby anatomy, and he told DH he could tell the sex by that photo.  Is that possible?  To determine the sex from an u/s pic the don't show the external goods?  Can you see testes/ovaries at a 20 week u/s? 

He didn't tell DH what he thinks it is, and I still don't want to know the sex, but it just kinda bothers me if one of our friends knows and we don't!  haha.