Unable to Pass Urine + Bladder Scan > 500 mL or patient distressed/uncomfortable e.g. at 300-400 mls
1	Encourage voiding in toilet/commode if safe 🚽 (privacy, running tap water, warm bath).
2	If fails → insert urethral catheter. If difficult despite senior help ➡️ call urology.
3	Start Tamsulosin 400 mcg OD × 48h, then attempt TWOC. ⚠️ Warn about postural hypotension.
4	If BPH with large prostate (raised PSA, LUTS) → consider Finasteride 5 mg OD (slow onset).
5	Look for reversible causes: delirium, AKI, constipation, UTI, pain, immobility.
6	Chronic painless retention (>1 L) → refer urology, often managed outpatient.

ℹ️ About

Commonest cause in men = Benign Prostatic Hyperplasia (BPH).
Symptoms: painful suprapubic discomfort, frequency, urgency, nocturia.
Dementia/mute patients → watch for agitation as sign of retention.

⚠️ Causes

Obstructive: BPH, prostate Ca, urethral stricture, stones, foreign body.
Drugs: Opiates, TCAs, antihistamines, decongestants, hyoscine.
Neurological: MS, Parkinson’s, spinal cord injury, stroke, spinal anaesthetic, tumour.
Women: Pelvic organ prolapse, gravid uterus, pelvic mass, vulvovaginitis, herpes.
Other: Alcohol binge, immobility, constipation.

🔍 Acute vs Chronic Urinary Retention

Feature	Acute 🚨	Chronic 🕐
Onset	Sudden (hours)	Gradual (weeks–months)
Symptoms	Painful, inability to void	Painless, overflow incontinence
Bladder	Tense, tender, distended	Very large, non-tender
Renal risk	AKI if untreated	Hydronephrosis, CKD
Causes	BPH, stone, stricture, drugs	Long BPH, neurogenic bladder
Catheterisation	Immediate relief	Less urgent; ISC/SPC often
Investigations	Bladder scan >500 ml, U&Es, PSA	USS bladder/kidneys, cystoscopy
Management	Immediate catheter, α-blocker, TWOC	α-blocker ± 5ARI, ISC/SPC, surgery
Complications	Pain, rupture, AKI	UTIs, stones, renal impairment

🧪 Investigations

Bladder scan / USS (diagnostic).
Bloods: FBC, U&E, Ca, CRP.
Urinalysis ± culture.

⚕️ Management Pearls

Immediate catheterisation if painful retention.
Do not clamp – rapid decompression is safe. ✅
Record residual volume + send urine if infected.
Post-obstructive diuresis: monitor urine output (>200 ml/hr is concerning).
If residual >1 L with AKI → admit under urology.

🌀 Trial Without Catheter (TWOC)

Use α-blocker for ≥2 days before TWOC.
If 2 failed TWOCs → long-term catheter or surgical option (e.g. TURP).

⚠️ Catheterisation Cautions (Seek Urology)

Pelvic/perineal trauma, fractured pelvis.
Known strictures or false passage.
Recent urethral surgery.
Unexplained haematuria.

💡 Suprapubic Catheter (SPC)

If SPC falls out → replace within 1 hour or tract closes.
Ensure bladder full before reinsertion (instil saline if needed).
Recurrent SPC problems → check for bladder stones.

🔄 Alternatives

Intermittent self-catheterisation (ISC).
SPC if recurrent/long-term need.
Needle aspiration (rare, temporary only).

📚 References

NICE CG97: LUTS in Men

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Acute Urinary Retention

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