Aah, 21 weeks scan, excited nie! Honestly, at that gestation the tech biasa boleh identify gender tapi it really depends on baby's position and the ultrasound machine lah, sometimes ada angle yang susah nak tengok. I punya friends yang kena scan berapa kali baru confirm hehe. Best bet is tanya the sonographer directly if they dapat see clearly, sebab sometimes kena tunggu next scan to be 100% sure, especially if baby shy!