Can ultrasounds be wrong??

I had an ultrasound at 15 weeks and the tech told me I was having a girl,Now i'm 21weeks and a diffrent tech says it's a boy..I was even told the  something looks wrong with the kidneys,When having this precedure I asked for a third confirmation,when third tech came to look he stated he didn't see anything wrong with my baby kidneys but it looked like a boy to  him too,i don't if he was covering tht part up for tht second tech.so i'm confused..any suggestions.I'm eager to find out the sex of my baby=(

[Mama19722013]

Well i would invest in finding me a new ultrasound profession and request for special test to be performed regarding my babies kidneys.  Now all i can say is boy or girl pray for a healthy lil bundle of joy....;)

[BalancedWifey]

If they say boy it's most likely a boy. If they say girl it could be a girl or undergrown boy.