gender question!?

So we were in the er last weekend due to pain and bleeding.. I have SCH but baby and I are fine. Any way the er ultrasound tech said he is guessing it's a boy. Then said it's kinda hard to tell and he wasn't to sure. We were 11weeks the time of the ultrasound. No mind you he asked if I am getting blood work to know the gender I said yes. He said okay good do that too. My question how right can he be? I read that the sex organs look the same that early on.