A catheter is a thin, flexible tube made of rubber, plastic, or silicone that is inserted into the body to drain fluid, deliver medication, or provide access for medical procedures. The most common type is the urinary catheter, which drains urine from the bladder when you can’t empty it on your own. But catheters are used throughout the body, from veins to the abdomen, for a wide range of medical purposes.
How Catheters Work
At its simplest, a catheter is a hollow tube with one or more channels inside it. In a urinary catheter, the largest channel lets fluid drain out. Other channels serve different purposes: one might inflate a small balloon that holds the catheter in place inside the bladder, while another can deliver medication or flush the area with sterile solution. The same basic principle applies to catheters used elsewhere in the body. They create a pathway into a space that’s otherwise difficult to reach.
Urinary Catheters
Urinary catheters are by far the most familiar type. They come in three main forms, each suited to different situations.
Indwelling (Foley) Catheters
An indwelling catheter stays inside the bladder continuously. It’s inserted through the urethra and held in place by a small water-filled balloon. A drainage bag, kept below bladder level, collects urine. These catheters are typically changed every six to eight weeks. During the day, some people are instructed to clamp the catheter periodically to help maintain bladder capacity, then leave it on continuous drainage overnight.
Intermittent Catheters
With intermittent catheterization, a thin catheter is inserted to empty the bladder and then removed right away. Most people using this method catheterize themselves four to six times over a 24-hour period. It’s commonly used for people with spinal cord injuries or neurological conditions that affect bladder control. Because the catheter doesn’t stay in place, the infection risk is generally lower than with an indwelling catheter.
Suprapubic Catheters
A suprapubic catheter bypasses the urethra entirely. Instead, it’s inserted through a small incision in the lower abdomen directly into the bladder. It functions like a Foley catheter once in place, with a balloon and drainage bag. This option is typically chosen when the urethra is damaged, blocked, or when long-term catheterization is needed and a urethral catheter isn’t practical.
Intravenous and Central Venous Catheters
Catheters placed into veins deliver fluids, medications, nutrition, or blood products directly into the bloodstream. The simplest version is the peripheral IV line placed in a hand or arm vein for short-term use. When treatment requires something more durable or the medications are too strong for small veins, a central venous catheter is used instead.
Central venous catheters are placed into large veins near the neck, chest, or groin. They come in several forms. A PICC line (peripherally inserted central catheter) enters through a vein in the upper arm and threads into a large vein near the heart. It can stay in place for weeks or months, making it useful for extended antibiotic courses or chemotherapy. Tunneled catheters are threaded under the skin before entering a large vein, and they include a small cuff that helps prevent bacteria from traveling along the tube. Totally implantable ports sit entirely beneath the skin, accessed with a needle when needed. These carry the lowest infection risk and require no daily maintenance of an external site.
Other Specialized Catheters
Catheters serve roles well beyond the bladder and bloodstream. Peritoneal dialysis catheters are placed into the abdominal cavity so that dialysis fluid can flow in and out, filtering waste from the blood when the kidneys can’t. Epidural catheters, threaded into the space around the spinal cord, deliver pain relief during labor or after surgery. Cardiac catheters are long, thin tubes guided through blood vessels into the heart to diagnose blockages or measure pressure.
What Insertion Feels Like
For urinary catheters, a healthcare provider cleans the area around the urethra with an antiseptic solution, then applies a lubricant (sometimes one that contains a numbing agent) to the catheter tip before gently threading it into the bladder. The process takes only a few minutes. You may feel pressure or a brief burning sensation during insertion, but it shouldn’t be intensely painful. The area around the urethra is cleaned using sterile technique, with sterile gloves, drapes, and a single-use packet of lubricant to minimize infection risk.
For central venous catheters or other specialized types, the skin is numbed with a local anesthetic before placement. Some procedures, like cardiac catheterization, involve light sedation as well.
Common Complications
The biggest risk with any catheter is infection. Urinary tract infections linked to catheters are the most common type of hospital-acquired infection, accounting for more than 30 percent of infections reported by acute care hospitals. Nationally, the rate falls between roughly 3 and 7.5 infections per 1,000 catheter-days, meaning the longer a catheter stays in, the higher the cumulative risk.
Beyond infection, indwelling urinary catheters can cause bladder spasms, which feel like stomach cramps as the bladder tries to squeeze against the balloon. Leaking around the catheter is common, especially during spasms or bowel movements. Blood or small bits of debris in the tube can occur and occasionally block drainage. Less common problems include urethral injury during insertion, urethral narrowing from scar tissue after repeated use, and bladder stones, though stones typically develop only after years of catheter use.
Central venous catheters carry risks of bloodstream infection, blood clots, and, rarely, damage to surrounding structures during placement. Tunneled catheters and implanted ports have lower infection rates than standard central lines because their design makes it harder for bacteria to migrate along the tube.
Reducing Infection Risk
Clinical guidelines from the CDC emphasize several principles that also matter for patients. Catheters should only be placed when truly necessary and removed as soon as possible. Every interaction with a catheter, whether insertion or routine care, requires hand hygiene before and after. The drainage bag should always stay below the level of the bladder to prevent urine from flowing backward. The connection between the catheter and the drainage tubing should not be disconnected unless absolutely necessary.
If you’re managing a catheter at home, keeping the insertion site clean, washing your hands before touching any part of the system, and ensuring the drainage bag doesn’t sit on the floor or get pulled on are the most practical steps you can take. Hospitals typically review daily whether each patient’s catheter is still needed, because removing it a day sooner meaningfully reduces infection risk.
Materials and Design
Most catheters are made from latex, silicone, or a combination of the two. Silicone catheters tend to be softer and are preferred for people with latex allergies or those who need a catheter for an extended period. Some catheters are coated with silver or antibiotics in an attempt to reduce bacterial growth, though research has shown mixed results on whether these coatings actually prevent infections in practice. The choice of material usually depends on how long the catheter will be in place and whether you have any material sensitivities.