Whats this 'labia 3 bones in the pelvis'? I am confused...
As far as I know the only way gender can be ascertained is by looking at the genitalia. When I had my girls, the sonographer told me it was difficult to see as the legs were closed..however she did comment ''I can see nothing that tells me it is a boy''. Therefore I would imgaine that at 20 weeks it would have been quite easy to see if it were a boy, as even with legs closed the scrotum hangs down quite a bit ;o)