Acute Urinary Retention
Definition
Acute urinary retention is defined as the abrupt development of:
- Inability to pass urine, and
- A painful / palpable / percussible bladder
Acute on chronic urinary retention refers to the development of acute urinary retention in a person who has previously had chronic urinary retention.
Aetiology
| Obstructive causes |
|
| Infection |
|
| Trauma | Bulbar urethral rupture classically causes acute urinary retention
|
| Medications |
|
Clinical Features
| Feature | Acute urinary retention | Chronic urinary retention |
|---|---|---|
| Onset | Sudden | Gradual |
| Pain | Severe suprapubic pain (patient would be restless and distressed) | Usually painless (patient is usually unbothered) |
| Ability to void | Unable to pass urine at all | May void small amounts or even overflow incontinence |
| Bladder | Tender | Non-tender |
| Palpable and dullness to percussion | ||
It is important to perform a DREDigital rectal examination to evaluate for prostatic conditions (esp. BPHBenign prostatic hypertrophy).
An important cause of acute urinary retention is cauda equina syndrome. Always check for other cauda equina syndrome red flags:
- Bilateral sciatica
- Saddle paraesthesia / anaesthesia
- Faecal problems (loss of sensation of rectal fullness)
- Erectile dysfunction / sexual function
- Loss of anal tone
Cauda equina syndrome may cause urinary incontinence, but this is typically a late finding. It initially presents with urinary retention, which can subsequently lead to secondary overflow urinary incontinence.
Investigation and Diagnosis
Confirmatory test: bladder scan [Ref1][Ref2]
- A post-void residual volume
The volume of urine left in the bladder immediately after the patient has voided as completely as possible
>200–400 mL supports urinary retention - Note: There is no universally agreed threshold, and cut-offs may vary between guidelines and clinical contexts. The key diagnostic point for acute urinary retention is the inability to pass urine AND a distended bladder confirmed by imaging or physical examination
- A post-void residual volume <100 mL is typically considered normal
Other initial tests:
- Urinalysis and urine MC&S to exclude UTI
- Renal function to check for AKI
Urodynamic testing is essential when initial evaluation is inconclusive or when neurologic or functional etiologies are suspected, as it distinguishes detrusor underactivity from bladder outlet obstruction. [Ref]
Management
Immediate management: urethral catheterisation
- Only attempt suprapubic catheterisation if urethral catheterisation has failed or is contraindicated (e.g. urethral trauma)
Subsequent management:
- Usually, a trial without catheter (TWOC) is attempted 1-3 days after initial catheterisation
- Offer an alpha blocker (e.g. alfuzosin, doxazosin, tamsulosin) for at least 2 days before removing the catheter
Information on types of urinary catheterisation
By route:
| Type | Key points | Typical uses |
|---|---|---|
| Urethral catheterisation | Passed via the urethra into the bladder | 1st line for acute urinary retention |
| Suprapubic catheterisation | Inserted directly into the bladder through the abdominal wall | Failed / contraindicated urethral catheter (e.g. urethral trauma, stricture) |
By catheter type:
| Catheter type | Key feature | When used |
|---|---|---|
| 1-way (straight / Nelaton) | No balloon | Intermittent catheterisation, single drainage |
| 2-way Foley | Drainage lumen + balloon | Most common indwelling catheter |
| 3-way Foley | Extra irrigation channel | Used for bladder irrigation (e.g. haematuria with clots) |
Chronic Urinary Retention
Definition
Chronic urinary retention is defined as a gradual (over months or years) development of the inability to empty the bladder completely
Aetiology
Chronic urinary retention is typically caused by long-standing pathologies:
- BPHBenign prostatic hypertrophy – most common
- Neurogenic bladder (e.g. diabetic autonomic neuropathy, spinal disease)
- Urethral stricture (e.g. from recurrent catheterisation, cystoscopy, recurrent STIs or urethritis)
- Pelvic organ prolapse (→ compress the urethra / bladder outlet)
Clinical Features
| Feature | Acute urinary retention | Chronic urinary retention |
|---|---|---|
| Onset | Sudden | Gradual |
| Pain | Severe suprapubic pain (patient would be restless and distressed) | Usually painless (patient is usually unbothered) |
| Ability to void | Unable to pass urine at all | May void small amounts or even overflow incontinence |
| Bladder | Tender | Non-tender |
| Palpable and dullness to percussion | ||
Diagnosis
Diagnostic criteria varies:
- NICE: post-void residual volume
The volume of urine left in the bladder immediately after the patient has voided as completely as possible
>1L OR the presence of a distended or palpable bladder - American Urological Association: post-void residual volume
The volume of urine left in the bladder immediately after the patient has voided as completely as possible
>300 mL on 2 separate occasions AND persisting for at least 6 months [Ref]
Investigations:
- Serum creatinine to assess renal function
- Consider imaging of the upper urinary tract
- Urodynamic testing is essential when initial evaluation is inconclusive or when neurologic or functional etiologies are suspected, as it distinguishes detrusor underactivity from bladder outlet obstruction [Ref]
Management
- 1st line: intermittent bladder catheterisation
- 2nd line: indwelling urethral / suprapubic catheter
- 3rd line: surgery (urostomy)
Active surveillance with post-void residual volume measurement, upper renal tract imaging and serum creatinine testing can be offered to those with non-bothersome LUTS secondary to chronic urinary retention
However, note that the presence of impaired renal function or hydronephrosis secondary to chronic urinary retention is an indication for intervention (i.e. catheterisation)
Whenever feasible, intermittent catheterisation is preferred over an indwelling catheter, due to lower infection risk (catheter-associated UTI) and better preservation of bladder function.
References
NICE BNF Treatment summaries Urinary retention
NICE guideline Lower urinary tract symptoms in men: management