AUR Summary

Definition

  • AUR: Abrupt inability to void urine
  • Chronic: Gradual incomplete emptying
  • Medical emergency requiring catheterization

Epidemiology

  • 3/1000 patients annually
  • 86% male, 14% female
  • 10% men aged 70-75 affected
  • >30,000 UK admissions/year

Key Causes

  • BPH (most common)
  • Prostate cancer
  • Medications
  • Neurological disorders
  • Constipation/UTI

Management

  • First-line: Urethral catheter
  • Alternative: Suprapubic catheter
  • Monitor for post-obstructive diuresis
  • Urology referral for most cases

Investigations

  • U&Es (renal function)
  • FBC (infection)
  • Urine dipstick
  • Avoid PSA initially

Disposition

  • Admit: Renal impairment, RV >1L
  • Discharge: Simple causes, RV <1L
  • Consider TWOC if appropriate

Acute Urinary Retention

Definition

Acute Urinary Retention (AUR)

Medical emergency characterized by abrupt inability to pass urine (over hours)

Chronic Urinary Retention

Gradual inability to empty bladder completely (over months/years) with residual volume >1L

Epidemiology

  • Incidence: 3/1000 patients annually
  • Gender distribution: 86% male, 14% female
  • 10% of men aged 70-75 will experience AUR
  • >30,000 UK hospital admissions/year

Causes

Outflow Obstruction

  • Urological:
    • BPH (most common in men)
    • Prostate/bladder cancer
    • Urethral stricture/stones
    • Clot retention
  • Non-urological:
    • Gravid uterus
    • Pelvic organ prolapse
    • Severe constipation

Other Mechanisms

  • Neurological:
    • Spinal cord lesions
    • Diabetic neuropathy
    • Multiple sclerosis
  • Medications:
    • Anticholinergics
    • Alpha-adrenergics
    • Opioids
  • Infections/Trauma

Clinical Features

Symptoms

  • Inability to void
  • Suprapubic pain
  • Confusion (elderly)
  • Obstructive LUTS

Examination Findings

  • Distended bladder:
    • Midline, fixed, dull to percussion
    • May extend above umbilicus
  • DRE findings (post-catheterization):
    • Prostate assessment
    • Faecal impaction
    • Perineal sensation

Bladder Ultrasound

  • Volume ≥300mL suggests retention
  • Limitations: Body habitus, edema, scarring
  • Clinical judgment supersedes scan results

Investigations

  • Essential:
    • U&Es (renal function)
    • FBC (infection/anaemia)
    • Urine dipstick (haematuria)
  • If renal impairment: Renal ultrasound
  • Avoid: PSA (defer for 2 weeks - high false positives)

Management

Immediate Treatment

  1. Urethral catheterization:
    • First-line management
    • Document: Residual volume, catheter size (14-16Fr)
  2. Suprapubic catheter (SPC):
    • If urethral fails
    • US-guided preferred
    • Contraindications:
      • Bladder cancer history
      • Haematuria/clot retention

Post-Obstructive Diuresis

  • Risk if RV >1000mL or renal impairment
  • Monitor hourly output (target <200mL/hr)
  • Watch for dehydration/hypotension

Disposition

Discharge Candidates

  • Simple retention (constipation/UTI/post-op)
  • RV <1L
  • Consider TWOC

Admission Required

  • Renal impairment
  • RV >1000mL
  • Sepsis/haematuria
  • Dehydration/dementia

Follow-up

  • Urology referral: Most catheterized patients
  • Alpha-blockers: If BPH features (per local protocol)
  • No follow-up needed: For constipation/UTI/post-op induced AUR