Urinary catheterization is a very common procedure and involves insertion of a soft flexible catheter (tube) into the bladder. The function of the catheter is to drain urine from the bladder into an attached bag.
Who needs urinary catheterization?
Urinary catheterization is widely used to drain and monitor urine. Urinary tubes are often inserted in patients undergoing long surgery. In nursing home patients and those who are physically disabled and unable to pass urine, catheters are often inserted.
Types of catheter

Intermittent catheter which is a very simple soft flexible tube. It is inserted into the bladder and immediately empties the bladder. The catheter is removed as soon as the bladder is emptied.
Individuals with urinary incontinence, or those with inability to void urine or those who have a bladder obstruction may benefit from intermittent urinary catheterization.
Indwelling catheter is a very soft tube but it also has an extra lumen (balloon) which can be enlarged with water. Once the catheter is inserted into the bladder, the other end of tube is blown up and the balloon will prevent the catheter from slipping out. These indwelling catheters are usually for more long term use.
The majority of individuals who have had a stroke or spinal cord trauma lose sensation in the lower pelvis and are unable to sense a full bladder. These individuals do benefit from indwelling urinary catheters.
Aseptic Technique
Urinary catheterization is a minor procedure but it does carry some risks like causing a urinary tract infection. Thus, the catheter must be inserted in a sterile fashion. All precautions must be taken to reduce the risk of bacteria entering the bladder. All patients who perform this technique at home should be taught the technique by a qualified health care professional.
Procedure
Urinary catheterization can be performed at the bedside as long as sterile precautions are undertaken. The individual inserting the catheter must wear sterile gloves and should have an assistant. The entire genital area especially near the urethral opening must be cleaned with an anti septic solution. A sterile lubricant like KY jelly is then liberally applied to the urethra and a local anesthetic gel is then inserted into the urethra. The anesthetic also acts like a lubricant and eases any discomfort.
One end of the catheter is then gently guided into the urethra and passed along into the bladder. One should always make sure there is urine flow from the other end of the catheter before attaching the catheter to the bag.
How to remove
When the use of the catheter is no longer needed, the balloon is deflated and the catheter is pulled out.
Anytime a catheter is placed for long term use, it must be changed with a new catheter every 4-6 weeks.

Aftercare
Once urinary catheterization has been performed, most individuals do require a certain amount of adjustment to the sensation of having a tube in the urethra. It is essential to drink adequate fluid and keep the urethra clean. Antibiotics are only administered to individuals who are at risk for urinary tract infections. Individuals who have urinary catheterization must be assessed to ensure that the catheter is working and there are no signs of an infection.
Risks
Urinary catheterization is a minor procedure but when not performed correctly it can lead to trauma to the urethra. Repeated use can lead to irritation of the urethra, introduction of bacteria and bleeding.

When used appropriately, urinary catheterization can help empty the bladder.