A urinary catheter is a small, flexible tube that can be inserted through the urethra and into the bladder, allowing urine to drain. The urethra is the tube that carries urine outside the body from the bladder.
A urinary catheter may be used for someone who is unable to urinate or who has difficulty moving and getting to the bathroom. It is also used to collect a urine sample from someone who is very ill or unable to provide a clean-catch urine specimen. Catheterization reduces the risk that the sample will be contaminated.
WebMD Medical Reference from Healthwise