Acute urinary retention and catheterisation

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Acute retention is a failure to empty a bladder that continues to fill. The usual presentation is escalating suprapubic pain and inability to void, but altered sensation, postoperative analgesia or pre-existing chronic retention may blunt the pain. The immediate task is safe decompression and identification of the cause. A successful catheter insertion is only the beginning of management: sepsis, an obstructed upper tract, neurological compression or post-obstructive fluid loss may remain dangerous after the bladder is empty.

A standard urethral approach is appropriate for many adults when no contraindication is identified and a trained clinician is available. The procedure depends on actual anatomy and history, not a generic male label. Trauma, reconstructive surgery, an artificial urinary sphincter or an established false passage requires a different plan. Children and pregnancy-related retention need their own specialist context. Explain the procedure, obtain consent, offer privacy and a chaperone, check allergies, and arrange help early if the anticipated procedure exceeds the operator’s competence.

Key points

Confirm an overfilled bladder: inability to pass urine with an empty bladder may reflect low urine production instead.
Pelvic trauma with blood at the meatus needs urgent assessment for urethral injury and specialist drainage planning before routine blind catheterisation.
Use aseptic technique, appropriate catheter length and lubrication, and confirm intravesical placement before balloon inflation.
Stop when passage is traumatic or uncertain; repeated forceful attempts can create a false passage.
Record initial retained urine separately from subsequent hourly production and observe for haematuria, hypotension and excessive diuresis.
In suitable men with acute retention, offer an alpha blocker before planned catheter removal; this is not a universal regimen for all retention mechanisms.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Outlet obstruction

Benign prostatic obstruction, stricture, clot or stone can prevent effective emptying. Pelvic masses and prolapse may obstruct in women, while previous procedures can alter outlet anatomy in either sex.

Impaired bladder activation

Anaesthesia, medicines, acute neurological disease and painful inflammation can disrupt sensation or detrusor activation. Several reversible and structural factors may combine in a single episode.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Continued filling
Urine entering a bladder that cannot empty produces progressive distension. Rising wall tension usually causes pain, but altered sensation or preceding chronic retention can reduce the apparent distress.
2
Pressure transmission
Marked or prolonged outlet obstruction can raise pressures upstream and impair renal filtration. The clinical consequence depends on duration, bladder compliance and whether one or both kidneys are affected.
3
Decompression response
Drainage relieves bladder tension but can be followed by haematuria, circulatory change or brisk renal water and solute excretion. Ongoing urine production must be distinguished from stored urine initially released.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Typical acute distension

The patient describes an urgent need to urinate, lower abdominal pain and inability to produce an effective stream. Palpation or percussion may identify a full bladder. Dribbling does not exclude retention, and an automated scan should be interpreted against the clinical examination.

Identify a precipitant

Recent anaesthesia, opioids, anticholinergic medicines, severe constipation, infection or a change in fluid intake may precipitate retention. Ask about prior LUTS, stricture, stones and pelvic procedures. Removing the precipitant improves the later chance of voiding but does not substitute for immediate drainage.

Urethral injury concern

Blood at the meatus after pelvic trauma, perineal bruising or known urethral injury makes routine blind catheterisation unsafe. Seek urgent urological and trauma advice for imaging and the drainage route. Blood generated during a difficult attempt is a reason to stop and reassess.

Neurological or systemic emergency

New saddle anaesthesia, bilateral leg symptoms or bowel disturbance needs an emergency spinal pathway. Fever, rigors, hypotension or flank pain raises concern for infected obstruction. Bladder drainage must run alongside systemic assessment, cultures and source-control decisions.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Bladder assessment and scanFirst step
Why
Confirm distension and distinguish retention from anuria or a misleading pelvic fluid collection.
Interpretation and limitations
A very full bladder supports urgent drainage, while a low volume requires evaluation of urine production and renal perfusion. Do not delay obvious painful retention solely to obtain an ideal scan. Reconcile a discordant scanner result with examination or ultrasound.
02
Creatinine and electrolytes
Why
Detect kidney injury, hyperkalaemia and a baseline for post-decompression monitoring.
Interpretation and limitations
Compare with previous values and record relevant medicines. Severe biochemical abnormalities require parallel treatment and renal or critical care discussion. Normal initial results do not remove the need to monitor a high-risk patient after large-volume drainage.
03
Urine specimen and infection assessment
Why
Identify symptomatic infection and guide treatment without relying on catheter colonisation.
Interpretation and limitations
Obtain a fresh appropriate specimen when infection is suspected. Assess systemic observations and blood cultures when indicated. Cloudy urine or a positive dipstick alone does not justify prophylactic treatment after an uncomplicated catheter insertion.
04
Targeted imaging and neurological assessment
Why
Resolve high-consequence alternative causes or persistent obstruction after bladder drainage.
Interpretation and limitations
Urethral imaging is specialist-directed when trauma is suspected. AKI with possible infected upper tract obstruction needs urgent imaging and urology. A normal perineal examination does not, by itself, exclude cauda equina compression when the history is concerning.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Low urine production

An empty bladder with little urine output suggests reduced production rather than retention. Hypovolaemia, severe kidney injury and upper tract obstruction need a different assessment.

Acute on chronic retention

A patient with longstanding impaired emptying may suddenly become unable to void. A large retained volume, previous enuresis and renal abnormalities suggest a longer process beneath the acute episode.

Clot retention

Macroscopic haematuria with clot obstruction can mimic uncomplicated retention but needs haematuria assessment and often a larger irrigation catheter managed by appropriately experienced staff.

Neurological compression

Cauda equina or other acute neural dysfunction may present with loss of bladder control or sensation. Associated bowel, saddle or limb symptoms change the urgency and investigation pathway.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Immediate procedureAseptic urethral drainageFirst stepAn adult has a distended painful bladder without an identified urethral contraindication.

1Review allergy to latex, lidocaine and chlorhexidine, previous instrumentation and implanted continence devices. Prepare sterile equipment, a suitable adult catheter and closed drainage system, then position and explain each stage to the patient.
2Clean the meatus, instil the selected sterile lubricant and allow its stated anaesthetic onset. In a male urethra advance a standard-length catheter gently to the bifurcation after urine returns; a female-length catheter must never be used in a man. For a female urethra, the EAUN procedure advances approximately another 2 cm after urine appears.
3Confirm that the catheter is in the bladder before inflating the balloon with the manufacturer-specified fluid and volume. Stop if inflation is painful or placement uncertain. Secure the tube, replace a retracted foreskin and keep the bag below bladder level.
4Permit free drainage and record retained volume and the time. Repeated clamping is not used routinely to stage decompression; monitor the patient for bleeding, circulatory change and high subsequent urine output.

02Difficult passageStop and obtain experienced assistanceResistance, bleeding or uncertainty occurs during a catheter attempt.

1Stop forceful advancement and do not inflate a balloon in an uncertain position. Reassess anatomy, prior stricture or surgery, patient discomfort and whether urine return is genuine.
2DefinitiveSeek an experienced catheter operator or urologist. A curved-tip catheter or guidewire-assisted/cystoscopic technique requires appropriate training; repeated blind attempts can make definitive drainage harder.
3When the urethral route is contraindicated or unsuccessful, arrange specialist suprapubic drainage after assessment of bladder distension, anatomy and bleeding risk. Prior lower abdominal surgery and an inadequately filled bladder can make blind suprapubic insertion hazardous.

03After drainageChoose observation and the next stepThe catheter drains but the patient’s risk and subsequent plan remain unresolved.

1Observe urine colour, initial blood pressure and ongoing urine production. Admit or continue monitored care for AKI, electrolyte disturbance, substantial diuresis, persistent haematuria, infection, frailty or inability to manage safely at home.
2Treat the precipitating cause and document whether this was acute retention or acute-on-chronic retention. In suitable men with a benign outlet mechanism, prescribe an alpha blocker before a planned trial without catheter; assess orthostatic risk first.
3Before discharge ensure the patient can empty the bag, has supplies and knows who can manage blockage or a failed trial. Record a named follow-up route and catheter removal or change plan rather than leaving a catheter without ownership.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

Single-use lubricating local anaesthetic for atraumatic urethral catheterisation when appropriate.

Instillagel urethral gel

For adult urethral catheterisation, instil 6–11 ml once: the EAUN female procedure uses 6 ml, while a male application may use the 11 ml syringe. Allow about five minutes for anaesthesia; administer into the urethra, never by injection.

Avoid with lidocaine, chlorhexidine or constituent allergy, or damaged or bleeding mucosa. The 11 ml syringe contains 230 mg lidocaine hydrochloride. Consider cumulative local anaesthetic exposure, cardiac or hepatic disease, epilepsy and antiarrhythmics before further administration. First-trimester use requires absolute necessity; do not import an injectable lidocaine maximum.

Adjunct before catheter removal in an appropriate adult male benign-outlet retention pathway.

Tamsulosin 400 microgram prolonged-release capsule

400 micrograms orally each day after the first meal, swallowed whole, started before the planned trial without catheter. Review ongoing need after the trial and subsequent symptom assessment.

This male BPH-associated regimen is not routine treatment for female or neurogenic retention. Avoid orthostatic hypotension history and severe hepatic insufficiency; use caution with creatinine clearance below 10 ml/min. Do not initiate when cataract or glaucoma surgery is scheduled; tell ophthalmology about past or ongoing exposure.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Instrument related injury

Forceful passage or balloon inflation within the urethra may cause bleeding, false passage and later stricture. Pain and resistance during the procedure are clinically meaningful warning signs.

Renal and electrolyte injury

Obstruction may cause AKI and biochemical disturbance, while its relief can expose substantial ongoing losses. A catheter does not itself correct every renal or electrolyte consequence.

Infection and dependence

An indwelling device introduces infection and practical burdens that increase with unnecessary duration. A recorded review and removal plan helps prevent a temporary intervention becoming indefinite by default.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Separate the first large drainage from newly produced urine by recording the time and emptying the measurement chamber; later hourly output determines whether diuresis is continuing.
Reassess pain and bladder distension after insertion. Persistent pain with little drainage demands a check for malposition, blockage or an alternative diagnosis.
Review renal function and electrolytes according to the initial abnormality and ongoing losses, with more frequent checks for unstable physiology or substantial replacement requirements.
At handover document catheter type, size, balloon volume, insertion difficulty, urine findings, complications and who will review the catheter and its underlying indication.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Balloon safety

Urine can appear before the entire catheter and balloon are safely within a male bladder. Correct advancement and painless inflation matter; a balloon inflated in the urethra can cause major injury.

Foreskin replacement

A retracted foreskin must be returned over the glans after the procedure. Failure to do so can cause paraphimosis, swelling and avoidable pain despite successful urinary drainage.

Gel is a medicine

The active UK product lists different lidocaine quantities from a simplified 20 mg/ml assumption. Use the actual syringe information, especially after previous anaesthetic exposure or a traumatic attempt.

Discharge readiness

A patient who cannot see the bag outlet, use their hands or reach support may be unsafe with an otherwise uncomplicated catheter. Demonstrated management ability is part of a successful procedure.

11Common pitfallsFrequent interpretation and management errors.

01
Do not keep attempting catheterisation through bleeding resistance; escalate before creating a false passage or making the eventual rescue procedure more difficult.
02
Avoid assuming a catheter that appears to have entered is safe to inflate; confirm bladder placement and respond to pain immediately.
03
Do not send a patient home solely because the initial pain is relieved if renal impairment, infection or continuing excessive output needs observation.
04
Routine prophylactic antibiotics are not a substitute for asepsis, nor are they automatically required for an uncomplicated insertion or catheter removal.

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