Ultrasound gender question

This may be a stupid question but does anyone know when they are scanning for gender do they look from the bottom or the top? 
We want to have a surprise but when in my last scan the clinician was showing me the baby's thigh bones and bladder in a view as if we were looking down on the babies tummy and I swear I saw a small male appendage between the legs. 
I have it in DVD but refuse to look back just in case it's really obvious. 
However most people's gender reveal photos show the babies butt so does that mean I can't have seen what I saw? 
Sorry if I sound stupid!