Is urine within the body sterile?

Q: I have always been told that urine within the body is sterile, until it comes outside and then it gets contaminated. Is this correct?

A:Yes. It is a fact that the bladder urine in a healthy person is sterile and has no infection. It may get contaminated with bacteria from the urethra and the surrounding tissues outside the urethra while being passed out. Likelihood of contamination is more in females than males. Urine, however, is wonderful culture medium and one bacterium would become 100,000 bacteria in two hours time at body temperature or room temperature. This is the reason why urine must show more than 100,000 colony forming units of bacteria per ml if urine has infection with bacteria in the urinary bladder. If contaminated on the way, the number of such colonies in urine is less than 100,000.