A Foley catheter, also called an indwelling urinary catheter, is a flexible plastic or rubber tube that is placed through the urethra and into the bladder. The urethra is the opening where urine comes out. The catheter helps drain urine from the bladder. There is a small balloon on the end of the tube that is inflated after the catheter is put in place. This keeps the catheter from sliding out of the bladder.
A Foley catheter is used when you are unable to pass urine (urinary retention). It's also used when there is loss of bladder control (incontinence). It's also used after bladder or prostate surgery.