A catheter is a thin, flexible tube that can put fluids into your body or take them out.
If you have trouble peeing or can’t control when you pee, a urinary catheter that goes into your bladder can get rid of urine for you. If you need blood or medicine, your doctor might use an intravenous catheter that’s connected to one of your veins with a needle. For example, if you had cancer and needed chemotherapy, that’s how you’d get it.