A urinary catheter in a male works by threading a thin, flexible tube through the penis, up the full length of the urethra, and into the bladder, where it allows urine to drain continuously or on demand into a collection bag. The male urethra is roughly 18 to 20 centimeters long and follows a curved path that passes through the prostate gland, which makes the process more involved than in females. Once the tube reaches the bladder, urine flows out under the pressure the bladder itself generates, essentially bypassing the normal voiding reflex entirely.
The Path the Catheter Follows
Understanding why catheterization feels different for men starts with the anatomy. The female urethra is short and relatively straight, while the male urethra takes a winding route. It begins at the tip of the penis, runs through the shaft, curves beneath the pubic bone, passes through the prostate, and finally enters the bladder. That prostatic segment is where things get tricky: the prostate sits like a ring around the urethra, and in many older men an enlarged prostate squeezes the channel even tighter. A clinician inserting a catheter has to navigate the tube through all of these curves without damaging the lining of the urethra.
Because of this longer, more complex path, clinical guidelines recommend using an anaesthetic-based lubricant gel (typically lidocaine) during male catheterization, whereas for women a plain water-based lubricant is considered sufficient.1International Journal of Urological Nursing. Does 2% Lignocaine Gel Reduce Urethral Catheterisation Pain in Women? A Systematic Review and Meta‐Analysis The gel serves double duty: it numbs the urethra and reduces friction as the catheter slides through. In practice, the gel is typically squeezed directly into the urethral opening and given a few minutes to take effect before the catheter is advanced.
Indwelling (Foley) Catheters
The most common type used in hospitals is the Foley catheter. It is a hollow tube, usually made of silicone or latex, with a small balloon near the tip. Once the catheter reaches the bladder, the balloon is inflated with a few milliliters of sterile water. That inflated balloon sits inside the bladder and prevents the catheter from sliding back out. The other end connects to a drainage bag, often strapped to the leg for ambulatory patients or hung from the bed frame for those who are bedridden.
Urine flows through the catheter primarily because of the pressure that builds up inside the bladder. As the bladder fills, that internal pressure pushes urine down the tube and into the bag. Wider catheters drain more efficiently because there is less friction against the inner walls of the tube. Research modeling urine flow through catheters confirms that increasing catheter diameter reduces the friction at the catheter wall, which in turn increases fluid velocity.2PubMed Central. Analysis of the urine flow characteristics inside catheters for intermittent catheter selection However, a wider catheter also means more stretching of the urethra, so clinicians aim for the smallest size that still drains well. Studies measuring catheter resistance found that beyond about 18 French (a unit of catheter diameter), upsizing gives diminishing returns: going from 18 to 20 French cut resistance by only about 19 percent, the smallest improvement between any two adjacent sizes tested.3PubMed. Does Size Matter? Measured and Modeled Effects of Suprapubic Catheter Size on Urinary Flow
Having a catheter in place also affects how the urethra handles normal urination around the tube. Computational modeling shows that the catheter takes up space inside the urethra, reducing the cross-sectional area available for any urine that might try to flow around it, which lowers the overall flow rate compared to normal urination.4PubMed. Influence of transurethral catheters on urine pressure-flow relationships in males: A computational fluid-dynamics study This is part of why men with a Foley catheter sometimes still feel urinary urgency even though the catheter is doing the draining for them.
Intermittent Catheterization
Not everyone who needs a catheter needs one left in place around the clock. Intermittent catheterization involves inserting a catheter, draining the bladder, and then removing it immediately. This is repeated several times a day on a schedule. Many people with spinal cord injuries, neurological conditions, or bladders that simply do not empty well learn to do this themselves at home.
The concept of “clean” rather than sterile self-catheterization was pioneered decades ago and demonstrated that patients could safely catheterize themselves after simply washing their hands, without the full sterile setup used in hospitals. Most adults in those early studies remained free from urinary tract infections and reported that gaining control over their urinary difficulties allowed them to return to a normal life.550 Studies Every Urologist Should Know. Clean Intermittent Self-Catheterization in the Treatment of Urinary Tract Disease That clean technique is now the standard for home use.
A practical question that comes up is whether to reuse catheters or use a fresh one each time. A review of the evidence found that single-use catheters, particularly those with a hydrophilic coating that makes them slippery when wet, were associated with a lower risk of urinary tract infections in nearly every study examined. Single-use catheters were also found to be cost-effective when infection-related healthcare costs were factored in.6PubMed Central. Clean intermittent catheterization: Single use vs. reuse Insurance coverage varies, though, and many people do reuse catheters out of necessity.
External (Condom) Catheters
For men who have urinary incontinence but do not have a bladder-emptying problem, an external catheter is sometimes a better option. A condom catheter fits over the penis like a sheath and connects to a drainage tube and bag. Nothing enters the urethra at all. This makes it far more comfortable for many men and dramatically reduces the risk of hospital-acquired infections compared to indwelling catheters.7INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH. ASSESSMENT OF INCIDENCE OF PENILE SKIN EROSION / ULCER IN PATIENTS WITH EXTERNAL CONDOM CATHETER URINARY DRAINAGE.
The main challenge with condom catheters is keeping them on. They can slip off, especially with movement or changes in penile size. Newer designs use a pressure-sensitive silicone adhesive on the inner wall of the catheter to reduce slippage, and some are adjustable after placement, allowing a tighter fit without cutting off circulation.8PubMed Central. Acanthus Condom Catheter: A Reusable and Adjustable Silicone Male External Catheter With Pressure-Sensitive Silicone Adhesive for Urinary Drainage Condom catheters are not suitable for men who need their bladder actively drained, since they only collect urine that the bladder expels on its own.
Suprapubic Catheters
When a catheter cannot be passed through the urethra at all, whether because of a severely enlarged prostate, a urethral stricture, or a traumatic injury, the alternative is a suprapubic catheter. This involves making a small puncture through the lower abdominal wall directly into the bladder and inserting the catheter through that opening instead. Once in place, it works the same way as a Foley: a balloon holds it inside the bladder and urine drains into a bag.9PubMed Central. Pigtail Suprapubic Catheter Placement in a Patient With Acute Urinary Retention and Abdominal Mesh
For some men, a suprapubic catheter is preferred long-term because it avoids the urethra entirely, which means less urethral trauma and irritation. It also leaves the genitals free, which matters for sexual activity and personal hygiene. The procedure does carry its own risks, including bleeding and, rarely, injury to surrounding structures, but for men who need long-term catheterization, many find it more manageable than a urethral catheter.
Why Infections Happen and How to Prevent Them
Catheter-associated urinary tract infections are one of the most common healthcare-acquired infections, and the mechanism is almost entirely tied to biofilm. Within hours of a catheter being placed, bacteria begin to attach to its surface and build a community encased in a sticky, protective matrix. Once that biofilm matures, the bacteria inside it become highly resistant to antibiotics, which is why catheter infections are notoriously stubborn.10PubMed Central. Role of biofilm in catheter-associated urinary tract infection Changing the catheter can sometimes help by physically removing the biofilm and improving the response to antibiotics.
Manufacturers have tried to combat biofilm with antimicrobial coatings, especially silver alloy coatings. But the reality is less encouraging than the marketing. Lab research using advanced microscopy showed that biofilm develops rapidly on all tested catheter materials, including silver-coated ones. Silver coatings appeared to have a bacteriostatic effect at best, meaning they slowed bacterial growth rather than killing bacteria outright. Many bacteria on silver-coated catheters shifted into a dormant-but-alive state that standard culture tests could not even detect, which helps explain why clinical trials of antimicrobial catheters have often found minimal benefit for patients.11PubMed Central. Biofilm Development on Urinary Catheters Promotes the Appearance of Viable but Nonculturable Bacteria
The single most effective strategy against infection remains keeping the drainage system sealed. Closed drainage systems, where the catheter connects to the bag through a sealed junction that is never broken open, significantly reduce infection rates. One evaluation of a closed drainage system in intensive care patients reduced catheter-associated infection to about 12 percent of patients, a meaningful improvement over open or frequently disconnected systems.12PubMed. Prevention of bacteriuria during urinary catheterization of patients in an intensive care unit: evaluation of the ‘Ureofix 500’ closed drainage system Even the design of the drainage bag’s measuring chamber matters: systems that empty via a non-return valve rather than by tilting show less contamination at the meter level, because tilting can allow bacteria to travel back up toward the catheter.13British Journal of Infection Control. In vitro test of different urine-meters in an experimental bladder-drainage model: prevention of ascending contamination depends on construction of the urine-meter
Bladder Spasms and Discomfort
One of the most unpleasant aspects of having a catheter is the cramping sensation that can hit without warning. Called catheter-related bladder discomfort, it is caused by the catheter irritating the bladder wall, which triggers involuntary contractions of the bladder muscle. These spasms can feel like an intense, sudden need to urinate, or like sharp cramps in the lower abdomen, even though the bladder is being drained.14PubMed Central. Catheter-Related Bladder Discomfort: How Can We Manage It? The mechanical presence of the catheter tip against the bladder wall can also contribute. Medications that relax the bladder muscle, such as those that block muscarinic receptors, are the usual first-line treatment. Adjusting catheter position or using a smaller catheter size sometimes helps as well.
What Happens to the Bladder Over Time
If a catheter stays in place for months or years, the bladder does not just sit idle and wait. It actively shrinks. One study tracking bladder capacity over time in patients with indwelling catheters found that capacity dropped from about 360 milliliters to roughly 220 milliliters during the first year alone, a loss of about 12 milliliters per month. Over the following eight years, it continued to shrink, though more slowly, eventually settling around 150 milliliters.15Neurourology and Urodynamics. Long‐term urethral catheter drainage and bladder capacity A bladder that has been drained continuously does not need to stretch and fill the way it normally would, so the muscle wall gradually contracts and loses its elasticity. This is one reason doctors try to remove catheters as soon as medically possible.
Removing the Catheter and the Trial Without Catheter
After an acute episode of urinary retention, the goal is usually to remove the catheter and see if the patient can urinate on their own, a process called a trial without catheter. For men whose retention was caused by an enlarged prostate, medications called alpha-blockers are typically started while the catheter is still in place. These drugs relax the smooth muscle around the prostate and bladder neck. Evidence supports giving them for two to three days before attempting removal, and keeping the catheter in for fewer than three to five days reduces complications without hurting the odds of success.16PubMed. Management of acute urinary retention in men with benign prostatic hyperplasia: Literature review and guidelines from the French Urological Association Male LUTS Panel (CTMH)
Still, the trial does not always work. In a large study of over 2,000 men presenting with their first episode of acute urinary retention, only about a third successfully voided after catheter removal. The rest needed the catheter reinserted or required surgery. The strongest predictors of failure were the degree to which the prostate protruded into the bladder, the patient’s age, the severity of prior symptoms, prostate volume, and how much urine had been retained. Men older than 65, or those with a prostate volume above roughly 56 cubic centimeters, had a notably lower chance of passing the trial.17PubMed. Predictors of successful trial without catheter following acute urinary retention in benign prostatic enlargement: A single centre, multivariate analysis
When Insertion Goes Wrong
The most feared complication during insertion is creating a false passage, where the catheter pushes through the urethral lining rather than following the natural channel. This can happen when the catheter meets resistance, often at the prostatic urethra, and too much force is applied. Another serious mistake is inflating the catheter balloon while it is still inside the urethra rather than the bladder. Both of these injuries tend to be manageable. For mild to moderate urethral injuries, conservative treatment with a catheter left in place (either urethral or suprapubic) for one to two weeks is typically enough for healing, because these mechanisms of trauma rarely cause a complete break in the urethra.18PubMed Central. Management of Catheter-Related Urethral Injuries in Male Children
For men with prostatic enlargement who present a difficult catheterization, clinicians sometimes switch to a Coudé catheter, which has a curved tip designed to navigate the upward angle at the prostate. If that fails, a suprapubic approach becomes the backup plan.
Newer Catheter Materials
Since biofilm is the root cause of most catheter infections and blockages, materials science is trying to build surfaces bacteria cannot cling to. One approach uses superhydrophobic silicone, a surface so water-repellent that bacterial cells and mineral deposits have difficulty adhering. In lab testing over 14 days, modified silicone surfaces showed significantly less bacterial attachment than commercially available silver-coated latex and standard silicone catheters, and analysis suggested the benefit came from a self-cleaning effect of the surface itself rather than any chemical antimicrobial action.19PubMed Central. Reduced Crystalline Biofilm Formation on Superhydrophobic Silicone Urinary Catheter Materials
Another line of research focuses on coatings made from natural macromolecules that give the catheter surface sustained lubrication and antibacterial properties. In animal testing, these coatings helped prevent both urinary tract injury during insertion and mineral encrustation during use.20PubMed. Natural Macromolecule-Based Lubricative Catheter Coatings with Sustained Adaptive Antibacterial Property for Encrustation and Infection Prevention Neither technology has reached widespread clinical use yet, but they represent a shift in thinking: rather than coating a catheter with something that kills bacteria (which, as discussed above, has shown limited benefit), the goal is to make a surface that bacteria and crystals simply cannot stick to in the first place.
Sex, Self-Image, and Living With a Catheter
One topic that rarely comes up in clinical settings but matters enormously to the people living with catheters is how it affects sex and identity. Qualitative research interviewing long-term catheter users found that many men described the catheter as affecting their sense of masculinity and sexual self-esteem. Some experienced pain, discomfort, or unexpected symptoms during sexual activity.21PubMed Central. How users of indwelling urinary catheters talk about sex and sexuality: a qualitative study These conversations are worth having with a healthcare provider but are often left unaddressed unless the patient raises them directly. For men with a urethral catheter, sexual intercourse is generally not feasible while the catheter is in place. Men with a suprapubic catheter have more options, since the genitals are not involved with the catheter pathway. Those using intermittent catheterization can time sexual activity around their catheterization schedule. None of these situations is simple, and the emotional weight of living with a catheter is just as real as the physical mechanics of how it drains urine.
A Long History of Trying to Get This Right
Catheters are ancient technology, though early versions were nothing like what exists today. During the Islamic Golden Age between the ninth and thirteenth centuries, physicians made meaningful advances: one introduced side perforations in catheter tubes to improve drainage and recommended flexible, lead-based materials, while another emphasized the use of soft, biocompatible materials for greater patient comfort and safety.22PubMed. The Historical Evolution of Urinary Catheters: Contributions From the Islamic Golden Age (9th-13th Century CE) The self-retaining balloon catheter that Frederick Foley developed in the 1930s remains, with minor refinements, the basic design used in hospitals worldwide. For a device that has been in continuous use for nearly a century, the Foley catheter has proven remarkably hard to improve upon. Most of the progress in recent decades has been incremental: better coatings, smoother surfaces, closed drainage systems, and protocols to get the catheter out sooner. The tube itself, though, would be recognizable to a surgeon from the 1940s.