Introduction

Normally, a person has two kidneys. The remainder of the urinary tract consists of two ureters (the tubes attached to the kidneys and to the bladder), the bladder, and the urethra (a tube attached to the bladder that leads to the outside of the body). Each kidney continuously produces urine, which then drains through the ureter into the bladder at a low pressure. From the bladder, urine drains through the urethra and exits the body through the penis in males and the vulva in females. Under normal circumstances, urine is free of bacteria and other infectious organisms.