How accurate of private gender scans?

[LJHH]

So I was lucky enough to be bought a private scan by my friends (they were sick of me banging on about the nub theory i think :) )
I was supposed to go last weekend but sadly had to postpone until this weekend, the postponement was for reasons out of my control so, naturally I sulked all day saturday!

I will be 17 weeks + 1 when I go - in a way i guess its better that we waited another week as the baby will be that tiny bit bigger.

I was just wondering how accurate these things really are? Obviously the all singing all dancing website claims to be over 99% accurate but they would say this?!
I'm so looking forward to finding out but will be devastated if they say one thing and the 20 week scan says another! (not that i have a preference but for the simple reason that we need to start buying things)
I have convinced myself its a boy so I will be completely shocked if its a girl!!

Has anyone had one of these and has any feedback?

Thanks :) x

That Chinese thing says it's a girl, I'm only 5+ 6 so well see.... will see what the nub looks like!
What if you're having fraternal twins then it couldn't be accurate!

At 13+ 5 I was told definitely a boy. At 20 weeks we were told girl! Am 23 weeks now. Some friends were told boy at 12 week nhs, girl at 16 week private and boy at 20 weeks nhs! Mistakes happen!

Our 20wk scan showed us pretty well as he just stuck it out there on the screen...along with a few bum flashes! X

I was right! We're team blue :)
He was hiding at first, I had to go for a walk, down a bottle of lucozade and a Mars bar and do some star jumps! But then she found his little bits! SO HAPPY!!!!!

Congratulations