ultrasound scan gender

Early ultrasound scan? Can this also explains the gender of the baby's sex?
I've been booked for a check of premature delivery by ultrasound, your baby's sex? Has anyone else had the scan? Their needs to be done between 21-25 weeks pregnant I am.
I am sure you could ask to take another peak and does not mind, but if you see your doctor before then asks if you will only able to get another looksy on sex. Best of luck to you.