An indwelling catheter is a flexible tube inserted into your bladder to drain urine continuously, held in place by a small water-filled balloon so it doesn’t slip out. Unlike a catheter you insert and remove each time you need to urinate, an indwelling catheter stays inside your body for days, weeks, or sometimes months. It’s one of the most common medical devices used in hospitals, and many people also live with one at home.
How an Indwelling Catheter Works
The design is straightforward. A thin, flexible tube has two internal channels running its length. One channel drains urine from your bladder into a collection bag. The other channel connects to a small balloon near the tip. Once a healthcare provider threads the tube into your bladder, they inflate that balloon with sterile water, which anchors the catheter so it can’t slide out on its own. Near the tip inside your bladder, tiny drainage holes (called eyelets) allow urine to flow into the tube.
The most common version is called a Foley catheter, named after the physician who designed it. It enters through the urethra, the same passage urine normally travels. The external end connects to a drainage bag that collects urine. Some indwelling catheters come fitted with a valve instead of a continuous drainage bag, letting you open the valve to empty into a toilet when it’s convenient and close it to let your bladder fill naturally between drainings.
Urethral vs. Suprapubic Placement
Most indwelling catheters go in through the urethra. The procedure doesn’t require anesthesia and takes just a few minutes. But when the urethra is damaged, blocked, or otherwise unusable, a suprapubic catheter is the alternative. This type enters through a small surgical opening in the lower abdomen, directly into the bladder. Placing a suprapubic catheter requires local, regional, or general anesthesia.
Both types work the same way once they’re in. The balloon holds the catheter in place, urine drains through the tube, and the external setup is similar. The difference is purely about the entry point and why one route is chosen over the other.
Why You Might Need One
Indwelling catheters aren’t used casually. The CDC outlines specific situations where they’re appropriate:
- Urinary retention or blockage: When you physically can’t empty your bladder on your own, whether from an enlarged prostate, nerve damage, or post-surgical swelling.
- Surgery: Certain operations, especially those involving the urinary tract or pelvic area, require a catheter during and after the procedure. Long surgeries or those involving large fluid volumes also call for one to monitor output.
- Critical illness: When precise tracking of urine output helps guide treatment in an ICU.
- Immobilization: Spinal injuries, pelvic fractures, or other conditions that keep you from getting to a bathroom.
- Wound healing: Open wounds in the sacral or perineal area that would be worsened by incontinence.
- End-of-life comfort: When managing toileting becomes a burden, a catheter can ease discomfort.
Outside these situations, healthcare providers are trained to avoid placing indwelling catheters and to remove them as soon as possible. The longer one stays in, the higher the risk of complications.
Sizing and Fit
Catheters are measured using the French scale, where higher numbers mean a larger diameter. For most adults, both men and women, the standard size is 14 to 16 French. This is what comes in most pre-packaged catheter insertion kits. Using the smallest effective size reduces irritation to the urethra and lowers the chance of tissue damage over time.
Catheter-Associated Urinary Tract Infections
The biggest risk of an indwelling catheter is infection. Catheter-associated urinary tract infections (CAUTIs) are among the most common hospital-acquired infections. Bacteria can travel along the outside of the tube or climb up through the drainage system, colonizing the bladder within days. The CDC’s most recent progress report shows a 10% decrease in CAUTI rates nationally compared to a 2015 baseline, with ICU settings seeing a 15% drop and general wards an 8% drop. Still, the risk is real any time a catheter is in place.
For a CAUTI to be formally diagnosed, the catheter must have been in place for more than two consecutive days, and you need to have symptoms like fever, pain near the kidneys, or (if the catheter has been removed) urgency, frequency, or burning during urination, along with a urine culture showing significant bacterial growth.
Blockages and Encrustation
For people with long-term catheters, blockage is a frequent problem. Certain bacteria, particularly one called Proteus mirabilis, produce an enzyme that raises the pH of urine and causes minerals to crystallize. These mineral deposits (made of struvite and hydroxyapatite, the same materials found in certain kidney stones) build up as a crusty layer inside the catheter tube. Research examining 20 blocked catheters found bacterial buildup on the inner surfaces of every single one, with Proteus mirabilis present in half of them.
When encrustation narrows or blocks the tube, urine backs up into the bladder, which can cause pain, leakage around the catheter, or in serious cases, kidney problems. If you notice urine has stopped flowing into the bag or is leaking around the catheter site, the tube may be blocked and needs attention.
Bladder Spasms
Having a foreign object sitting in your bladder can trigger involuntary muscle contractions. These bladder spasms are common with long-term catheterization and feel like a sudden, intense urge to urinate or a cramping sensation in the lower abdomen. The force of a spasm can overpower the drainage capacity of the catheter, pushing urine out around the tube instead of through it.
If spasms are frequent or painful, medications that relax the bladder muscle can help. These work by calming the overactive contractions so the catheter can drain normally. Spasms sometimes also improve when a catheter is repositioned or replaced with a smaller size that causes less irritation.
Daily Care at Home
If you’re living with an indwelling catheter, a few basic practices prevent most problems. The drainage bag must always stay below the level of your bladder. If the bag sits higher, urine can flow backward into the bladder and bring bacteria with it. The catheter tube is secured to your inner thigh with a fastening device to prevent tugging, which reduces irritation at the insertion site and keeps the tube from being accidentally pulled.
You’ll empty the bag through a valve at the bottom without disconnecting it from the catheter. Keeping that closed system intact is one of the most important steps in preventing infection. Most people use a larger overnight bag while sleeping and a smaller leg bag during the day that’s less visible under clothing. Cleaning around the catheter entry site daily with soap and water, staying well hydrated, and watching for signs of infection (cloudy or foul-smelling urine, fever, pain) are the essentials of daily management.
How Long One Stays In
There’s no fixed schedule for routine replacement. Guidelines emphasize removing indwelling catheters as early as clinically possible rather than changing them on a calendar. For people who need long-term catheterization, replacement timing depends on individual factors like how quickly encrustation develops or whether infections recur. Some people go several weeks between changes, while others need more frequent swaps. Your healthcare team will establish a schedule based on how your body responds.