86. Urinary retention

Question 1

Index conditions.

Answer 1

BPH (by far most common cause)
Prostate Ca
Neurological causes (e.g. MS, prolapsed disc)
Post-operative
Drug-related (e.g. antimuscarinics, TCAs)
Blocked catheter

Question 2

Classification.

a) Acute
b) Chronic

Answer 2

a) Emergency characterised by the abrupt development of the PAINFUL inability to pass urine (over a period of hours)
b) Gradual (over months or years) development of the inability to empty the bladder completely, characterised by a residual volume greater than one litre or associated with the presence of a distended or palpable bladder (may or may not be painful)

Question 3

Aetiology: structural

a) Men
b) Women
c) Both

Answer 3

a) BPH, Prostate Ca, meatal stenosis, paraphimosis, penile constricting bands, phimosis.
b) Prolapse (cystocele, rectocele, uterine), pelvic mass (gynaecological malignancy, uterine fibroid, ovarian cyst), retroverted gravid uterus.
c) bladder calculi, bladder cancer, faecal impaction (constipation), gastrointestinal or retroperitoneal malignancy, urethral strictures, foreign bodies, stones.

Question 4

Aetiology: infective/inflammatory

a) Men
b) Women
c) Both

Answer 4

a) Balanitis, prostatitis and prostatic abscess.
b) acute vulvovaginitis, vaginal lichen planus and lichen sclerosis, vaginal pemphigus.
c) Bilharzia, cystitis, HSV (particularly primary infection), peri-urethral abscess, varicella-zoster virus

Question 5

Aetiology: drug causes

Answer 5

• Anticholinergics (e.g., antimuscarics like oxybutynin, antipsychotic drugs, antidepressant agents, anticholinergic respiratory agents).
• Opioids and anaesthetics.
• Alpha-adrenoceptor agonists.
• Benzodiazepines.
• Non-steroidal anti-inflammatory drugs.
• Detrusor relaxants.
• Calcium-channel blockers.
• Antihistamines.
• Alcohol.

Question 6

Aetiology: neurological

a) Autonomic/ peripheral nerve
b) Brain
c) Spinal cord

Answer 6

a) Autonomic or peripheral nerve (eg, autonomic neuropathy, diabetes mellitus, Guillain-Barré syndrome, pernicious anaemia, poliomyelitis, radical pelvic surgery, spinal cord trauma, tabes dorsalis).
b) Brain (eg, cardiovascular disease (CVD), multiple sclerosis (MS), neoplasm, normal pressure hydrocephalus, Parkinson’s disease).
c) Spinal cord (eg, invertebral disc disease, meningomyelocele, MS, spina bifida occulta, spinal cord haematoma or abscess, spinal cord trauma, spinal stenosis, spinovascular disease, transverse myelitis, tumours, cauda equina).

Question 7

Causes of post-operative retention

Answer 7

Pain.
Traumatic instrumentation.
Bladder overdistension.
Drugs (particularly opioids).
Decreased mobility and increased bed rest
Specific procedures, e.g. Suburethral sling procedures for stress incontinence

Question 8

Assessment.

a) History - pertinent symptoms to enquire about
b) Examination

Answer 8

a) Neurological (CES, other), LUTS, pain!, bowel opening, systemic (fever, weight loss, etc.)
b) - Bladder (distended and dull percussion almost up to umbilicus);
- PR in both (anal tone and sensation; faecal impaction; prostate in men)
- male genitourinary (phimosis, meatal stenosis, urethral discharge)
- PV (vulval/vaginal inflammation, cystocele)
- Neurological

Question 9

Investigations.

a) Bloods
b) Orifices
c) XR/imaging
d) Special tests

Answer 9

a) FBC. UEs, creatinine, eGFR. Blood glucose.
Prostate-specific antigen (PSA): NB: this is elevated in the setting of AUR so is of limited use at this stage.

b) Urinalysis - check for infection, haematuria, proteinuria, glucosuria. MSU.

c) - Ultrasound - post-void residual urine as well as looking for hydronephrosis and other structural abnormalities of the renal system.
- CT scan - used to look for pelvic, abdominal or retroperitoneal mass causing extrinsic bladder neck compression.
- MRI/CT brain scan - used to look for intracranial lesions (eg, tumour, stroke, MS).
- MRI scan of the spine - used to look for disc prolapse, cauda equina syndrome, spinal tumours, spinal cord compression, MS.

d) Investigations such as cystoscopy, retrograde cystourethrography or urodynamic studies may also be undertaken depending on the suspected cause of retention

Question 10

Management: acute retention

a) Initial
b) Further
c) possible alternative drug class that may be used

Answer 10

a) Catheterise + alpha-blocker (for at least 2 days before removal of catheter to prevent further retention)
b) TWOC if possible
c) Cholinergics (e.g. neostigmine)

Question 11

Management: chronic retention

a) First line
b) Further management

Answer 11

a) Offer intermittent self-/carer catheterisation before indwelling if possible
b) Treat underlying causes; conservative, medical and surgical

Question 12

Complications of retention

Answer 12

• UTIs.
• Acute kidney injury./ hydronephrosis
• Post-obstructive diuresis (marked natriuresis and diuresis with electrolyte disturbance, including hypokalaemia, hyponatraemia, hypernatraemia and hypomagnesaemia).
• Urolithiasis
• Post-retention haematuria - 2-16% in one study after rapid decompression via a catheter and usually self-limiting.

Question 13

BPH

Answer 13

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