Urinary retention is not being able to empty your bladder all the way. You have a problem in your urinary tract or in the nerves that control it. The urinary tract is made up of the kidneys, ureters, bladder, and urethra. The kidneys make urine and it drains into tubes called ureters. The ureters join to the bladder. The bladder squeezes out the urine and it leaves the body through the urethra. If this problem comes on all of a sudden, it is acute urinary retention or AUR. With AUR, you may not be able to pass any urine at all, even though your bladder is full. If the problem is chronic, or lasts a long time, you may not be able to empty your bladder all the way. This problem can cause damage to the kidneys or the bladder.