Urethral catheter

A tube in the bladder via the urethra. The ED problems: a blocked catheter (painful retention - and in a spinal-injured patient, a hypertensive emergency), bypassing, and a balloon that will not deflate.

Adult & paediatricUrinaryStated practice - no UK guideline found

Also called: urethral catheter, indwelling catheter, Foley catheter, IDC, urinary catheter, long-term catheter, catheter, bladder catheter

What it is

A urethral catheter is a soft tube passed up the urethra into the bladder, held there by a water-filled balloon, draining urine into a bag or valve. It is used for retention, for monitoring, and long-term for people who cannot empty their bladder. The problems that reach an ED are mechanical and infective: blockage, bypassing (leaking around it), a balloon that will not deflate, trauma/bleeding, and catheter-associated infection.

The quiet killer is in one specific patient. In someone with a spinal cord injury at or above T6, a blocked catheter distends the bladder and can trigger autonomic dysreflexia - a hypertensive crisis that causes stroke, seizures or death. For that patient the blocked catheter is not a nursing job, it is a medical emergency, and the treatment is to drain the bladder. Catheters are used in adults and children; long-term catheters are mostly adult.

How to recognise it

A tube emerging from the urethra connected to a drainage bag or catheter valve, held by a balloon inside the bladder.
Problems present as pain and no drainage (blockage), leakage around the tube (bypassing), inability to deflate the balloon to remove it, visible blood, or systemic infection.
Expected care: The catheter should be changed at least every 3 months - so a very old catheter may itself be the problem.

What it gets confused with

A suprapubic catheter enters through the lower abdomen, not the urethra. The ED difference that matters: a dislodged suprapubic catheter must be replaced within hours before its track closes, whereas a urethral catheter can be re-passed per urethra. Trace where the tube enters the body.

Open that entry →

What goes wrong

Blocked catheter (and autonomic dysreflexia)

Pain, bladder distension and little or no urine draining; in a cord-injured patient, a pounding headache and dangerously high blood pressure.

Red flag
Unblock or replace it promptly. In a patient with a spinal injury at or above T6 this is autonomic dysreflexia, an emergency - the SOP: If there is retention of urine, catheterize the patient (or re-catheterize if the problem is a blocked catheter) and sit them up. BAUS: blockage can cause a lot of pain and needs urgent attention.

Bypassing (leaking around the catheter)

Urine leaking alongside the catheter, often with a dry or working bag.

Red flag
Bypassing is frequently a sign the catheter is blocked, not too small: It can also happen if your catheter is blocked and stops draining. Check for blockage and bladder spasm before assuming the catheter needs upsizing.

Balloon will not deflate / cannot remove

A catheter due for removal where the balloon port will not let the water out, so the catheter cannot be withdrawn.

Red flag
Do not pull hard or cut the catheter blindly - that can shear it or injure the urethra. This is a urology problem (specialist balloon-deflation techniques); refer rather than forcing.

Trauma, bleeding, or catheter-associated infection

Frank haematuria (sometimes after a catheter is pulled with the balloon up), or fever, loin/suprapubic pain and feeling unwell.

Red flag
A catheter pulled out with the balloon inflated tears the urethra - treat bleeding and refer. For infection, treat symptoms, not colonisation: It is inevitable that you will get bacteria in your urine but generally this does not need treating; you only need antibiotics if you have symptoms of infection.

The first ten minutes

If the catheter is not draining and the bladder is full, relieve it - flush or, more reliably, replace the catheter so urine drains. When you re-catheterise, confirm urine returns before inflating the balloon, and in an uncircumcised man replace the foreskin afterwards to prevent paraphimosis.
Ask about spinal cord injury. In a patient injured at or above T6 with a blocked catheter and a headache or high blood pressure, treat autonomic dysreflexia: sit them up and drain the bladder at once (see the panel).
For bypassing, look for blockage and spasm first rather than reflexively upsizing the catheter.
For a balloon that will not deflate, do not force or cut it - call urology.
Treat infection only on symptoms, send a sample if symptomatic, and do not treat asymptomatic bacteriuria.
Involve urology / the continence team for recurrent blockage, non-deflating balloons, trauma or haematuria.

Do not

Do not leave a blocked catheter in a spinal-injured patient while you investigate the headache.

In a cord injury at or above T6 a distended bladder causes autonomic dysreflexia - a hypertensive emergency. Draining the bladder is the treatment; delaying it risks stroke, seizures and death.

Do not pull a catheter without checking the balloon is deflated.

Withdrawing a catheter with the balloon still inflated tears the urethra and causes significant bleeding, especially in men.

Do not inflate the balloon until you have seen urine return.

Inflating the balloon while the tip is still in the urethra (not the bladder) ruptures the urethra. Confirm urine drainage first; if none drains, do not inflate - reassess or get help. And in an uncircumcised man, always reduce the foreskin after catheterising, or a retracted foreskin can cause paraphimosis.

Do not treat a positive culture in an asymptomatic catheterised patient.

All long-term catheters are colonised; antibiotics are only indicated with symptoms of infection. Treating colonisation drives resistance without benefit.

Do not keep upsizing a bypassing catheter.

Bypassing is usually from blockage or bladder spasm; a larger catheter often makes spasm and leakage worse. Find and treat the cause.

Who owns it

The urology / continence team (and paediatric urology in children) own catheter problems; the patient's spinal injury centre must be involved for autonomic dysreflexia. Tell them whether the catheter is draining, the indication, how long it has been in, and - critically - whether the patient has a spinal cord injury.

Autonomic dysreflexia: why a blocked catheter can kill

In a patient with a spinal cord injury at or above T6, a blocked or kinked catheter - or any noxious stimulus below the injury - can trigger a hypertensive crisis. The device problem that looks like a nursing job is a time-critical medical emergency, and the treatment is to remove the cause, usually by unblocking or replacing the catheter. This is the single most dangerous fact in the urinary-device group.

What it is, and who it happens to: Autonomic Dysreflexia (AD) is a potentially dangerous (and occasionally fatal) clinical syndrome of uncontrolled hypertension that affects people who have a spinal cord injury. It most often affects people with a neurologic level of spinal cord injury at or above the sixth thoracic cord segment (T6); it is very unlikely to occur with injuries below T10.
The bladder is the usual trigger: The commonest causes are a distended bladder or bowel or a urinary tract infection (UTI). Bladder distension accounts for Bladder distention (80% of all cases) - so a blocked, kinked or clamped catheter in a cord-injured patient is a prime cause, alongside a loaded rectum.
How it presents: A pounding headache with a blood pressure far above the patient's usual low baseline: frontal headache is the commonest symptom of AD, and it should always prompt measurement of the blood pressure. It is an emergency - AD is a medical emergency and requires immediate intervention to reduce the possibility of serious consequences including retinal detachment, intracranial haemorrhage, seizures and death.
What to do first: The simplest approach is to identify and remedy the cause. Sit the patient up (immediately sit the person up if the patient is supine) to drop the blood pressure, then go straight to the catheter: unkink it, and If there is retention of urine, catheterize the patient (or re-catheterize if the problem is a blocked catheter). Use plenty of local-anaesthetic lubricant gel when instrumenting the urethra, so re-catheterisation does not itself add to the noxious stimulus. If the cause cannot be found or the pressure stays dangerously high, treat the hypertension and get senior help.
Do not treat the headache and miss the cause: The patient's own SCI centre and their personal AD plan are the experts; call them. The fix is mechanical - restore drainage and empty the bladder - not analgesia. Giving an opioid for the headache while the catheter stays blocked leaves the trigger in place.

Management of Autonomic Dysreflexia in Adults (NHS trust SOP, 2024), implementing the Consortium for Spinal Cord Medicine 'Acute management of autonomic dysreflexia' guideline and NICE NG41 · read in full

Who to call

The team and the criteria are national. The phone number is local, and this tool does not know it. Find it once, now, and write it on the department's own card — that is the part no website can do for you.

Say the device name first: Open with laryngectomy, LVAD, shunt — the single word changes who comes and what they bring. Do not bury it in the history.
Say what you have already established: Whether the device is patent, whether it has been removed or disturbed, and what you have already tried. The specialist is deciding whether to walk or run.
Ask who owns it out of hours: Device ownership and the on-call route often differ from the implanting specialty, and it is frequently a regional centre rather than your own hospital.
The patient's own team is a resource, not an afterthought: Named nurse specialists, home-care companies and device helplines answer questions nobody else can, and the patient usually has the number.

What the patient will be carrying

Long-term catheter patients and carers usually know the catheter size, change schedule and continence-team contact, and cord-injured patients often carry an autonomic-dysreflexia card describing their own emergency plan.

Scope of this page

This page covers the ED response to a urethral catheter problem: blockage (including autonomic dysreflexia), bypassing, a non-deflating balloon, trauma and catheter-associated infection. It does not teach routine catheterisation technique or the full continence-management plan, and it does not cover suprapubic catheters (a separate entry with a different emergency). Catheters are used in adults and children; long-term use is mostly adult and paediatric care is directed by paediatric urology.