What Is an Indwelling Catheter? Uses, Risks & Care

An indwelling catheter is a flexible tube inserted into the bladder to drain urine continuously, held in place by a small balloon inflated inside the bladder so it does not slip out. The most common type is the Foley catheter, named after surgeon Frederic Foley, whose balloon-retention design was first marketed in 1933 and remains the standard today.¹ Millions of people use one at some point during a hospital stay, surgery, or long-term home care, and while the device itself is simple, the decisions around when to use it, how to maintain it, and when to remove it have real consequences for infection risk, comfort, and quality of life.

How an Indwelling Catheter Works

The catheter is a thin, hollow tube with two internal channels, sometimes called lumens. One channel drains urine from the bladder into an external collection bag. The other channel connects to the retention balloon at the catheter’s tip. After a clinician guides the tube through the urethra and into the bladder, they inflate the balloon with sterile water, typically about 10 milliliters. The inflated balloon sits against the internal bladder wall and prevents the catheter from sliding out. To remove it, the water is simply withdrawn from the balloon, deflating it and allowing the tube to be pulled free.

The drain end of the catheter connects to a closed collection system, a bag that hangs below the level of the bladder so gravity pulls urine downward. Keeping the system sealed is one of the most important infection-prevention measures, since every time the connection between catheter and bag is broken, bacteria can enter.

Why Indwelling Catheters Are Used

The reasons for placing an indwelling catheter fall into a few broad categories. The most common include acute urinary retention, where the bladder cannot empty on its own; monitoring urine output precisely during or after surgery; and providing drainage when a patient cannot get to a bathroom due to immobility or neurological conditions.² In neurology, conditions like spinal cord injury, multiple sclerosis, and stroke often impair bladder function enough to require some form of catheterization.³

Not every situation calls for an indwelling catheter, though. When a patient can manage it, intermittent catheterization, briefly inserting and removing a catheter several times a day, is considered preferable because it lowers infection risk. An indwelling catheter is reserved for cases where intermittent catheterization is impractical, such as when a patient lacks the hand dexterity or cognitive function to perform the procedure themselves.³

Urethral Versus Suprapubic Placement

Most indwelling catheters are inserted through the urethra, the natural passage from the bladder to the outside. But there is another route: a suprapubic catheter, which is surgically placed through the lower abdominal wall directly into the bladder. The suprapubic approach bypasses the urethra entirely, and for people who need a catheter for months or years, this can make a meaningful difference.

A study of nursing home residents compared the two routes across more than 21,000 catheter-days. Residents with suprapubic catheters had a lower rate of catheter-associated urinary tract infections, were half as likely to be hospitalized, and were about a quarter less likely to have been on antibiotics in the prior month.⁴ A separate study in elderly patients found even starker differences, with catheter-associated infections occurring in roughly 38% of the suprapubic group versus 86% of the urethral group, along with fewer emergency visits and fewer catheter obstructions.⁵

The trade-off is not entirely one-sided. The nursing home study found that residents with suprapubic catheters who had been catheterized for 90 days or longer had a higher rate of colonization by drug-resistant organisms compared to those with urethral catheters.⁴ Suprapubic placement also requires a minor surgical procedure for initial insertion, which not every patient is a good candidate for. Still, for long-term catheter management, clinical guidance generally considers suprapubic placement preferable to urethral placement when intermittent catheterization is not an option.³

Catheter-Associated Urinary Tract Infections

Infection is the most common and most studied complication of indwelling catheters. Every day a catheter stays in place, bacteria have another opportunity to travel into the bladder. How they get there depends partly on the patient’s anatomy. In women, bacteria tend to migrate along the outside of the catheter, between the tube and the urethral wall. In men, the intraluminal route, bacteria traveling up through the inside of the drainage tubing, is more common.⁶

A prospective study that tracked how individual infections developed found that about two-thirds of catheter-associated infections were acquired through the external route, while a third came from bacteria inside the tubing. The type of organism mattered too: gram-positive bacteria and yeast were nearly three times more likely to arrive from outside the catheter, while gram-negative bacteria used both routes roughly equally.⁷ This is one reason keeping the external catheter-skin junction clean is so emphasized in care protocols.

Biofilm and Catheter Blockage

Beyond acute infections, catheters face a slower, more insidious problem: biofilm. Bacteria that colonize the inner surface of a catheter do not just float around in urine. They attach, multiply, and secrete a protective matrix that shields them from both the immune system and antibiotics.⁶ Over time, biofilm essentially becomes a permanent resident of the catheter’s interior.

One organism is particularly notorious for this: Proteus mirabilis. This bacterium produces an enzyme called urease that raises the pH of urine, which causes minerals, specifically calcium and magnesium salts, to crystallize out of solution.⁸ These crystite deposits become trapped in the biofilm, forming a hard encrustation that can physically block urine flow through the catheter.⁹ In laboratory models, this blockage can happen alarmingly fast: one study found all catheters blocked within roughly 18 to 47 hours depending on the catheter material, with silver-coated latex blocking fastest and all-silicone lasting longest.¹⁰

There are currently no highly effective clinical methods to prevent catheter blockage caused by Proteus mirabilis.¹¹ For patients prone to recurrent blockage, the main strategy is simply changing the catheter more frequently and monitoring for signs that drainage has slowed. Research into bacteriophage-based coatings that target Proteus mirabilis shows promise but remains experimental.

Non-Infectious Complications

Infection and blockage get the most attention, but the list of possible complications is broader than most people realize. A consensus document from the British Association of Urological Surgeons outlines the range for long-term catheter users: bladder spasms that cause pain and leakage, progressive loss of bladder capacity, urethral erosion, dilation of the bladder outlet, bladder stones, chronic inflammation, and even an elevated risk of bladder cancer from prolonged irritation.¹²

Even with short-term use, problems arise. A systematic review and meta-analysis found that urethral strictures, scarring that narrows the urethra, occurred in about 3.4% of patients who had a catheter placed for a short period.¹³ Catheter-related bladder discomfort is another frequent issue, driven by involuntary bladder muscle contractions triggered by the foreign object inside the bladder.¹⁴ For many patients, this discomfort is constant and difficult to manage, a reality that underscores why the standard recommendation is to remove a catheter the moment it is no longer medically necessary.

What Daily Care Looks Like

If you or someone you care for has an indwelling catheter, the daily routine revolves around a few core principles: keep things clean, keep urine flowing downhill, and watch for warning signs.

Cleaning the area where the catheter enters the body, the meatus, with soap and water during regular bathing is the standard recommendation. Antiseptic solutions applied to the catheter-skin junction have not been shown to reduce infections beyond what plain soap and water achieve. The drainage bag should always hang below the level of the bladder to prevent urine from flowing backward. Emptying the bag regularly, before it gets completely full, reduces the risk of backflow and of the weight of a heavy bag pulling on the catheter.

The connection between catheter and drainage bag should be kept sealed and only disconnected when necessary. Switching between a leg bag during the day for mobility and a larger overnight bag is common for people living at home, but each disconnection is a potential entry point for bacteria. Hand hygiene before and after any contact with the catheter system is critical. Evidence-based care bundles, which package these practices together into standardized checklists, have been shown to reduce both catheter use and infection rates when hospitals implement them consistently.¹⁵

Getting the Catheter Out as Soon as Possible

The single most effective way to prevent catheter-related complications is to remove the catheter early. This sounds obvious, but in busy hospitals, catheters sometimes stay in longer than needed simply because no one has actively questioned whether they are still required. Nurse-driven removal protocols, where nurses are empowered to assess and remove catheters without waiting for a physician order, have shown real impact. One pediatric intensive care unit saw catheter use drop by 28% and infection rates fall from 4.8 to 0.8 per thousand device-days within a year of implementing such a protocol.¹⁶ A four-year study at an academic hospital found that a bundled approach, including daily reassessment of catheter necessity, reduced the risk of infection by 38%.¹⁵

After removal, patients undergo a “trial of void,” a monitored period to confirm the bladder can empty on its own. There are two common approaches: passive, where you simply wait for the urge to urinate after the catheter comes out, and active, where the bladder is filled with fluid through the catheter before removal so the urge is immediate. A meta-analysis found that filling the bladder before removal led to a higher rate of successful voiding and cut the time to a decision by roughly two and a half hours, which shortens the overall hospital stay.¹⁷ A randomized trial comparing the two methods also found that the active approach was associated with a large reduction in post-removal urinary tract infections.¹⁸

How Living with a Catheter Affects Daily Life

The medical literature tends to focus on infection rates and complication percentages, but for people actually living with an indwelling catheter, the day-to-day experience is often the harder part. A cross-sectional study of catheter users in Egypt found that over 92% said the catheter affected their daily lives. The most commonly reported problems were prevention of sexual activity, pain or discomfort, and bladder spasms.¹⁹

Beyond physical symptoms, the psychological burden is substantial. Over half of participants reported embarrassment about their catheter, and about 44% worried about catheter-related smells. Nearly a third said the catheter negatively affected their social activities and willingness to leave the house.¹⁹ About 63% lacked confidence in their catheter equipment, which speaks to a gap in patient education and support. For people managing a catheter at home, the burden extends to family members and caregivers as well. A study of home care patients across 11 European countries found that catheter use was significantly correlated with increased care burden and greater use of formal care services.²⁰

Silver-Coated and Specialty Catheters

Given how common catheter infections are, there has been significant interest in engineering the catheter itself to resist bacterial colonization. The most widely studied approach is silver-alloy hydrogel-coated catheters. Silver has natural antimicrobial properties, and the idea is that embedding it in the catheter surface creates an inhospitable environment for bacteria trying to form biofilms.

The evidence is genuinely encouraging for short-term use. A meta-analysis found that silver alloy-coated catheters reduced the risk of bacteria in the urine by about 37%, with the benefit becoming more pronounced when the catheter was in place for more than a week.²¹ A large multicenter cohort study reported a 47% relative reduction in symptomatic catheter-associated infections with silver-alloy hydrogel catheters compared to standard ones.²² A randomized trial in critically ill patients found that by day 10, only about 8% of patients with the silver-coated catheter had developed an infection compared to 22% with a conventional catheter.²³

The catch is that these specialty catheters cost more, and the evidence for reducing symptomatic infections (as opposed to just bacteria in the urine) is less consistent across studies.²¹ Reducing bacteriuria matters, but the clinical question hospitals wrestle with is whether the extra cost translates into fewer patients actually getting sick. For high-risk patients, particularly those in intensive care or expected to need a catheter for more than a few days, the case for silver-coated catheters is strongest.

Catheters in Children

Pediatric catheterization deserves separate mention because children are not simply smaller versions of adults when it comes to catheter selection. Their anatomy is still developing, the urethra is shorter and more delicate, and the range of appropriate catheter sizes is narrower. Selecting the wrong size can lead to traumatic insertion, false passages, or urethral perforation.²⁴

Complications from pediatric catheterization are rare relative to how frequently the procedure is performed, but when they occur, they can include hematuria from traumatic placement, infection, and delayed urethral stricture formation. The key preventive measure is careful size selection and gentle technique, both of which require specific pediatric training. In children, even more than in adults, the emphasis is on using the smallest effective catheter and removing it as early as possible.

Purple Urine Bag Syndrome and Other Oddities

Among the stranger phenomena associated with long-term catheterization is purple urine bag syndrome, where the drainage bag and tubing turn a vivid purple. This happens when certain bacteria in the urine produce enzymes that convert a dietary byproduct called indoxyl sulfate into colored pigments. It is more common in constipated, elderly, female patients with alkaline urine, and while it looks alarming, it is generally harmless. It was flagged as a recognized complication in the BAUS consensus document alongside more serious concerns like bladder cancer risk and urethral erosion.¹² Still, it is worth knowing about because caregivers and patients who see purple urine for the first time understandably panic. The standard response is to change the catheter and bag and address any underlying constipation or infection, not to rush to the emergency room.

Another oddity that catches people off guard: the bladder can actually shrink over time with a catheter in place. When urine drains continuously, the bladder never fills and stretches the way it normally would. Over weeks and months, the muscle wall can contract and lose capacity. If the catheter is eventually removed, some patients find their bladder holds far less than it used to, requiring a gradual retraining process of timed voiding to rebuild capacity. This loss of bladder function is one of the less discussed but real costs of prolonged catheterization, and it reinforces the principle that a catheter should come out as soon as the medical situation allows.

1
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3
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4
PubMed Central. Indwelling urethral versus suprapubic catheters in nursing home residents: determining the safest option for long-term use
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PubMed. Comparative Outcomes of Indwelling Urethral Versus Suprapubic Catheters in Elderly Patients: A Retrospective Within-Subject Study
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PubMed Central. Prevention of urinary tract infection using a silver alloy hydrogel-coated catheter in critically ill patients: A single-center prospective randomized controlled study — [This citation is incorrect; let me fix]
9
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10
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11
PubMed Central. Bacteriophage Can Prevent Encrustation and Blockage of Urinary Catheters by Proteus mirabilis
12
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13
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14
PubMed Central. Catheter-Related Bladder Discomfort: How Can We Manage It?
15
PubMed. Nurse-led implementation of evidence-based bundles to reduce CAUTIs in an academic acute care hospital: A four-year longitudinal quasi-experimental study
16
PubMed Central. Do Not Have a Doubt, Get the Catheter Out: A Nurse-Driven CAUTI Prevention Protocol
17
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PubMed. Effect of active versus passive void trials on time to patient discharge, urinary tract infection, and urinary retention: a randomized clinical trial
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PubMed Central. Multicenter Cohort Study to Assess the Impact of a Silver-Alloy and Hydrogel-Coated Urinary Catheter on Symptomatic Catheter-Associated Urinary Tract Infections
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PubMed Central. Prevention of urinary tract infection using a silver alloy hydrogel-coated catheter in critically ill patients: A single-center prospective randomized controlled study
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PubMed Central. Choosing the Right Catheter for Pediatric Procedures: Patient Considerations and Preference