Urinary catheterisation

The procedure everybody assumes they can do, and the one that quietly does the most harm

This is the most delegated procedure in the hospital. It is handed to the most junior person present, taught once, and thereafter assumed. It is also a common cause of hospital-acquired infection, a recognised cause of permanent urethral injury, and a reliable source of complaints.

Do not underrate it. A catheter placed badly in a man with an enlarged prostate can produce a false passage, a stricture, and years of trouble. A catheter left in because nobody reviewed it produces a bloodstream infection. Both are avoidable, and neither is avoided by confidence. It sounds like a simple procedure, and I assure you there is a great deal more to it than anybody is ever taught. Read on.

Indications, and the ones that do not count

Good reasons in intensive careAccurate hourly urine output where that is genuinely guiding treatment. Acute retention or obstruction. Neurogenic bladder with failure to empty. Facilitating healing of sacral or perineal wounds in an incontinent patient. Prolonged surgery or immobility. Some catheters also measure core temperature, which can be a legitimate reason in itself.
The commonest bad reasonBecause the patient is in intensive care. Ventilation, sedation and vasopressors are not by themselves indications, and “everyone here has one” is not a clinical decision. Nor is nursing convenience, incontinence alone, or obtaining a specimen that could be caught clean.
The one to think hardest aboutHourly urine output only helps if somebody acts on it. In a stable patient two days into their admission, ask what decision the number would change. Often the honest answer is none, and that is the moment the catheter should come out.

Stop, in these

Suspected urethral injury. Blood at the meatus, a scrotal or perineal haematoma, a high-riding or impalpable prostate, or a pelvic fracture. Do not pass a catheter. Attempting it can convert a partial urethral tear into a complete one. Urology, and usually a suprapubic catheter.

Recent urological surgery or reconstruction, where an ill-judged catheter can undo the operation. Ask the surgeon rather than guessing.

Known difficult anatomy — a stricture, an artificial sphincter, a previous radical prostatectomy. Someone with an artificial urinary sphincter needs it deactivated first, and catheterising around one causes erosion.

Consent, including when it cannot be given

This is an intimate procedure and it is treated too casually. The standards are the same as for anything else: explain what you are doing and why, what it will feel like, and what the alternatives are. Offer a chaperone and document the offer.

The sedated or unconscious patientCannot consent, and it is done on the basis of necessity in their best interests. That does not lower the standard of dignity or gentleness, and it does not remove the need to document why it was necessary. Tell them what you are doing anyway.
The patient who refusesA patient with capacity may decline, and a delirious or distressed patient who is pulling away is telling you something even if they cannot argue their case. Stop. Find out whether it is fear, pain, previous trauma, or a considered objection. Very few catheterisations are so urgent that they cannot wait twenty minutes for a conversation, or for someone the patient trusts.
Ask about previous experienceSomeone who has had a traumatic catheterisation before will often say so if asked, and will not volunteer it. That single question changes who should be doing it and how.
Cultural and personal preferenceSome patients will strongly prefer a clinician of a particular gender. Where that can be accommodated, accommodate it.

Doing the ordinary one well

Most difficulty is manufactured at the start. The steps below are the ones that prevent it.

Use enough local anaesthetic gel, and wait. The commonest technical failing. Instil 10 to 20 mL slowly, pinch the meatus closed so it does not run straight back out, and leave it three to five minutes. The gel is a lubricant, an anaesthetic and a dilator, and none of those work in thirty seconds.
Hold the penis upward, at about ninety degrees. This straightens the penoscrotal angle. Lowering it towards the abdomen as the catheter reaches the bulbar urethra can help the last few centimetres.
Insert almost to the hilt. Not to the first sight of urine. In a man the catheter goes in to the bifurcation before the balloon is anywhere near the bladder, and inflating early is how urethras are torn.
See urine before you inflate. This is the rule that prevents the injury that matters. If there is no urine, do not inflate — flush 20 mL of saline and aspirate it, or put the gel applicator on the end and use it as a sucker. No urine means either the wrong place or an empty bladder, and you need to know which.
Inflate with sterile water. Not saline, which crystallises and can jam the deflation channel. Not air, which floats. The volume printed on the catheter, no more and no less — an underfilled balloon sits eccentrically and an overfilled one distorts.
Replace the foreskin. Written down because it is forgotten, and a retracted foreskin left behind a swollen glans is a paraphimosis, which is painful, avoidable and occasionally surgical.
Document properly. Size, how easily it went, residual volume, whether urine was seen before inflation, and who did it. The next person to face a difficulty will thank you.

Three things that mean stop

Resistance. Advance steadily and gently, and let the catheter find its way. If it will not go, it will not go. Do not force it — really, do not force it. Force is what converts a tight prostate into a false passage, and a false passage into a stricture. There is no amount of pushing that turns a failed catheterisation into a good one, and every extra newton makes the next operator's job harder.

The catheter that coils. If it stops advancing and you keep pushing, a soft catheter does not bore forward — it doubles back on itself. Sometimes the tip reappears at the meatus, which is unmistakable; more often it simply folds in the urethra and you feel the resistance change while the catheter still seems to be going in. Coiling means the tip has met something it cannot pass. Withdraw, do not advance further, and change something — the size, the tip, the operator, the technique.

A balloon that will not inflate easily. This is the most important signal on the page, and the one most often overridden. A balloon sitting free in the bladder inflates smoothly and painlessly. Resistance on the syringe, or pain in a conscious patient, means the balloon is not in the bladder — it is in the urethra or the prostate. Stop. Deflate it completely. Do not push the plunger harder to see whether it gives. Advance the catheter further, confirm urine, and only then inflate. Inflating against resistance is the single act that causes the worst injuries in this procedure.

Before you start on a difficult one

Put the ultrasound on the bladder. It answers a question you would otherwise guess at: is there any urine in there? A patient who is anuric from acute kidney injury does not need three increasingly traumatic attempts to prove it, and a bladder containing 900 mL tells you the problem is downstream and worth persisting with.

The difficult male

The obstacles are anatomical and they are predictable: benign prostatic enlargement, a urethral stricture, a previous transurethral resection, prostate cancer or its treatment, phimosis, meatal stenosis, a buried penis in an oedematous or obese patient, and — very commonly — a false passage created by whoever tried before you.

Go up a size, not downThe counterintuitive one. A larger catheter is stiffer and less likely to buckle or fold into a false passage, so a 16 French often passes where a 12 would not. Small and soft is the wrong instinct in an enlarged prostate.
Use a Coudé tip, oriented correctlyThe angled tip is designed to ride over the prostatic ledge. It only works pointing anteriorly, so the balloon inflation port must be at twelve o'clock throughout. A Coudé rotated as it advances is worse than a straight catheter.
Get an assistant to apply perineal pressureSteady pressure in the perineum can direct the tip up into the prostatic urethra, and it is free.
For the buried penisDownward pressure at the base of the shaft with a hand on either side will often bring the meatus into view long enough for an assistant to pass the catheter.
Two attempts, then change somethingNot a third go with the same catheter by the same person. Change the operator, change the catheter, or change the technique. Repeated attempts are how false passages are made, and every one makes the next attempt harder.

The guidewire, which is the modern answer

When the blind attempts have failed, the bedside solution is a Seldinger technique rather than force. A soft hydrophilic guidewire is passed gently down the urethra; if it meets resistance it is withdrawn and repassed rather than pushed. Once two-thirds of it has gone without the tip reappearing at the meatus, it is in the bladder. A Council-tip catheter — which has a hole at its tip for exactly this purpose — is then railroaded over the wire.

With direct vision by flexible cystoscopy, success rates in the published series are very high. Blind wire passage is a reasonable bedside step in trained hands. Both are much safer than persistence with a catheter that will not go.

Introducers: the honest answer is don't

Rigid metal introducers and urethral sounds still appear on trolleys and in older teaching. They carry materially higher rates of urethral injury, false passage and outright failure than a guidewire, and current teaching reserves them for urologists.

If you are an intensivist, an emergency physician or a trainee, the correct sequence when the catheter will not pass is: optimise the basics, try a larger or Coudé catheter, consider a guidewire if you have been trained in it — and then call urology. Not reach for a sound. The procedure that ends with a phone call has a far better outcome than the one that ends with a stricture.

And the option people forget at two in the morning

When the urethral route has failed and the patient is in retention, the answer may be a suprapubic catheter rather than another attempt or a long wait. It is worth having in mind as a live option rather than a last resort, because the alternative is often several more traumatic passes by increasingly tired people.

It is not a soft option. It needs a bladder that is genuinely distended and can be seen on ultrasound, and it is unsafe in the non-distended bladder, in significant coagulopathy, and where previous lower abdominal surgery may have brought bowel down onto the bladder. Bowel injury during suprapubic placement is a recognised and serious event, which is why ultrasound guidance and an experienced operator matter.

So the useful question at two in the morning is not “can I get a catheter in?” but “is this patient obstructed, and if so who is placing what, and where?” A comfortable, unobstructed patient can safely wait for the morning list. A patient in painful retention cannot, and that is the conversation to have with urology now rather than at six.

A separate piece in this series will cover suprapubic catheters properly.

The difficult female, which is a different problem

Less discussed and not rare. The difficulty is almost always finding the meatus rather than passing the catheter: obesity, oedema, limited hip abduction, and atrophic change that retracts the urethra posteriorly.

Feel for itWhere the meatus cannot be seen, a finger in the vagina will find it as a buttonhole in the anterior midline, and a small catheter can be slid along the finger with gentle pressure against the anterior wall.
Here, smaller and firmer is betterThe opposite of the male problem. A stenosed, retracted meatus takes a smaller, firmer catheter more easily than a large soft one.
If it goes into the vagina, leave it thereThen pass a second, sterile catheter into the urethra alongside it. The misplaced one is now a landmark rather than a failure, and is removed afterwards.
RepositionLateral position, or reverse Trendelenburg, or a pillow under the sacrum. In a difficult pelvis, changing the position beats changing the catheter.

Which catheter

Standard two-way Foley	Drainage and a balloon. 14–16 Fr covers almost everything in an adult.
Three-way	A third channel for irrigation. For frank haematuria and clot retention, where a two-way will block. Larger, and less comfortable.
Coudé / Tiemann	Angled tip for the enlarged prostate. Port at twelve o'clock.
Council tip	Open at the tip so it can be passed over a guidewire. The one you want when the wire is in.
Silicone vs latex	Silicone for anyone staying catheterised for weeks, for latex allergy, and where encrustation is a problem. Latex is softer and cheaper for short-term use.
Temperature-sensing	Gives a continuous core temperature. Worth choosing deliberately in a patient being actively warmed or cooled.

Complications, and the ones nobody records

Catheter-associated urinary tract infectionThe one with the numbers attached. Risk rises with every day the catheter stays in. Nothing in the maintenance bundle matters as much as the catheter not being there — closed system, bag below the bladder, no routine bladder washouts, and daily review of whether it is still needed. Antibiotics are not given routinely, either at insertion or while the catheter is in, and asymptomatic bacteriuria in a catheterised patient is not treated. See the note below for the exceptions.
Urethral trauma and false passageAlmost always from inflating the balloon in the urethra or from repeated forced attempts. Frank blood on the catheter, pain out of proportion in a conscious patient, or a balloon that will not inflate freely. Stop and get help. The long-term consequence is a stricture, which is somebody's next twenty years.
Bleeding, and who bleedsA little blood after a difficult insertion is common. Frank haematuria, or bleeding that does not settle, is not. The patients who turn a minor urethral graze into a problem are the ones intensive care is full of: therapeutic heparin or other anticoagulation, thrombocytopenia, disseminated intravascular coagulation, liver failure, uraemic platelet dysfunction, antiplatelet agents. In them, a traumatic catheterisation can produce clot retention, a blocked catheter and a bladder that will not empty — which then needs a three-way catheter and irrigation, and occasionally urology. Where the catheter is not urgent, correcting or pausing the coagulopathy first is a reasonable decision. Where it is urgent, it is a reason for the most experienced pair of hands available rather than the most junior.
ParaphimosisEntirely iatrogenic and entirely preventable, and the reason replacing the foreskin has its own step above.
Post-obstructive diuresisAfter relieving a chronically obstructed bladder, watch the output and the electrolytes. Some patients pass litres and become genuinely hypovolaemic. Modern practice is to drain completely rather than in aliquots, but to monitor afterwards.
The balloon that will not deflateDo not cut the catheter and hope. It is a urology problem, and there are several graded approaches before anything invasive.
The harm without a codeDiscomfort, indignity, delirium in an older patient who keeps pulling at something they do not understand, and immobility because a bag is tethering somebody to a bed. None of these appear in an infection audit and all of them are reasons to take it out.

Antibiotics: not routinely, but not never

Routine prophylaxis for a straightforward catheterisation is not recommended, and treating asymptomatic bacteriuria in a catheterised patient does harm rather than good.

There are patients in whom a single prophylactic dose is worth considering, and intensive care has more of them than most wards: a difficult or traumatic insertion with bleeding or multiple attempts, significant immunosuppression or neutropenia, prosthetic heart valves or other implanted material, known colonisation with a resistant organism, recent urological surgery or instrumentation, and the catheter change in a patient with a history of catheter-associated sepsis.

Endocarditis risk needs a more careful answer than it usually gets. Current cardiology guidance does not recommend antibiotic prophylaxis for genitourinary procedures purely to prevent endocarditis, and a valve abnormality on its own is not a reason to give a dose before a straightforward catheterisation. What is reasonable, in the highest-risk group — a prosthetic valve or prosthetic material used in valve repair, previous infective endocarditis, or certain congenital heart disease — is cover directed at enterococci when that patient has a known or suspected urinary tract infection, or known enterococcal colonisation, and the urinary tract is being instrumented. The distinction is between prophylaxis for a clean procedure, which is not indicated, and treating an infected urinary tract before manipulating it in someone who cannot afford a bacteraemia.

This is a decision to make deliberately and to record, guided by your own antimicrobial guideline rather than by habit. The trap is the middle ground: a dose given reflexively to everyone achieves nothing except resistance, and a dose withheld from the neutropenic patient after a bloody third attempt is a different kind of error.

Anuria: flush before you treat

A catheterised patient has been passing 70 mL an hour all shift and the last hour reads zero. The reflex is a fluid bolus, or a look at the blood pressure, or a phone call about acute kidney injury.

Check the catheter first. Sudden, complete cessation of urine in a patient who was draining well is far more often mechanical than renal. Kidneys that are failing taper off; a blocked catheter stops. Look along the tubing for kinks, loops above the bladder and a clamped bag, feel and scan for a distended bladder, and flush the catheter with 20 to 50 mL of sterile saline. If the bladder empties, you have your answer and you have saved the patient a litre of fluid they did not need.

Blockage is usually clot, debris or encrustation, and it is commonest in exactly the patients above — the ones who bled a little at insertion, or who have been catheterised a long time. If the catheter will not flush, it is replaced rather than persuaded. And if the bladder is empty and the catheter flushes freely, then the anuria is real and now you know it, which is a much better place to start from.

Changing it: should you, and how often

The instinct to change a catheter on a schedule is strong and mostly wrong.

Do not change it routinelyRoutine replacement at fixed intervals does not prevent infection. Every change is a fresh chance to introduce organisms and to traumatise the urethra. In a patient in intensive care for a fortnight, the catheter should generally stay until there is a reason to change it.
Reasons to change itBlockage or encrustation. Damage or a leaking balloon. A change of purpose, such as needing irrigation. And in suspected catheter-associated infection, replacing a long-standing catheter before starting treatment is reasonable, since the biofilm on the old one will not be sterilised by antibiotics.
Long-term catheters are differentA patient who is going home with one moves to a planned schedule, silicone typically up to about twelve weeks and latex much sooner. That is a community management question, not an intensive care one, and the interval is individual rather than universal.

“Shall we change the catheter? The fever has no source.”

This request arrives most nights, usually by analogy with a central line. The analogy does not hold, and the answer depends entirely on which of three situations you are actually in.

An unsourced fever, with nothing to suggest the urine. Do not change it. No guideline recommends replacing a urinary catheter in order to look for a source. Almost every catheter is colonised within days, so a culture taken at this point will very often grow something, and that something will very often be treated. Catheter-associated infection is substantially over-diagnosed in intensive care, and this is how. An unsourced fever is a reason to look harder for the source, not a reason to change the catheter.

A fever with pyuria, where you genuinely suspect the urine. Now change it — and take the specimen from the new catheter. This is a best-practice recommendation in the critical care guidance on new fever, and the reason is diagnostic rather than therapeutic: urine drawn through an established catheter samples the biofilm on that catheter, not the bladder. A culture from the old catheter can tell you what is growing on the plastic while telling you very little about the patient.

An established catheter-associated infection you have decided to treat. If the catheter has been in more than about two weeks and is still needed, replacing it is recommended, on the reasoning that antibiotics will not sterilise an established biofilm. Worth knowing that this is a weak recommendation on limited evidence, that practice varies widely between countries, and that a multicentre randomised trial is currently testing whether the change is necessary at all.

And the analogy itself is worth correcting. Central lines are not changed on a schedule either — routine replacement to prevent infection has been advised against for many years. A line is exchanged or removed when it is suspected of being the source. That is exactly the right principle here, and applying it properly means asking whether the urine looks like the culprit rather than whether the catheter is old.

The most important review is the daily oneEvery ward round: does this patient still need a catheter? If nobody can say what decision the urine output is changing, it comes out. That single habit prevents more harm than every insertion technique on this page.

Challenge for you

Tell me about a difficult catheterisation you have had, and how you managed it.

What made it difficult, what you tried, what worked, and what you would do differently. The ones that ended with a phone call are as instructive as the ones that ended with a catheter, and the near misses are the most instructive of all. I will collect the replies into a follow-up piece.

Send me yours

The button opens a reply straight to me. If your device blocks it, write to icuandyou@icloud.com instead.