I have to say I thought I saw "something" at the 12 week scan. We had a private scan at 16 weeks and the boy bits were 100% evident and we were talked through the two boy bits and shown picutres on screen (she didn't print those pictures!! Hehe) but at the 21 week scan it was very obvious indeed, yes we could see everything again in all it's glory so 100% certain it's a boy. We were told at 12 weeks that they don't say even if they can tell (gender becomes visable to the naked eye at 12 weeks but can be harder to detect on the ultrasounds unless it's a 3D etc) and then at the 16 weeks they said although they will tell us and told us how certain they were, i.e. 75% certain or 90% certain etc she told us they would never say "100% guarenteed" type thing. The 21 week scan she said she'd tell us if we wanted to know (some hospitals don't due to populations of heavier religious or racial influence etc and women being under pressure to provide the "correct" gender) and again we were just given a percentage but being shown the boy bits in full detail on both the 16 and 21 week scan were now over 1000% certain it's a boy!! It really depends on the hospital, position of the baby (have some coke or some chocolate before the scan, it get's baby wiggling away and not curled up in a sleepy ball!) and the skill of the scanning person I suppose. If you want to know you'll more than likely get to know. You can always ask for a second opinion and they will then have to get a 2nd scanning person to have a look and offer their view also.
I wouldn't have been able to tell myself, but the lady said there were no dangly bits so it's a girl lol 
