At 20 weeks, we will be going for detailed scan. Is it possible for us to not know the gender during the scan?

My baby's gender was just determined upon my last ultrasound (33 weeks) - but it's just because when we decided to have an ultrasound (not required but my hubby wants to find out if he's having a tenor or soprano to be) at 23 weeks, my baby didn't front face at all! It took us like almost an hour but she really don't want to show up her gender or even her face. Yea, a silly one! :) If you're having a baby girl, her vagina is now fully developed on week 22: http://sg.theasianparent.com/week-by-week-pregnancy-guide-week-22/ Basically, ultrasounds according to this source is not mainly performed to determine the sex of a baby but the second ultrasound done bet 18-22 weeks is to make sure the baby is growing and developing properly and which when parents can learn the sex of the baby. http://www.livescience.com/45582-boy-or-girl.html