Common causes of post-operative poor urinary output

• Pre-renal
  • Hypovolaemia
  • Hypotension
  • Dehydration
• Renal
  • Acute tubular necrosis
• Post-renal
  • Benign prostatic hypertrophy
  • Anticholinergic or alpha adrenoreceptor antagonist drugs (commonly used in anaesthetics)
  • Pain (particularly hernia operations)
  • Psychological inhibition
  • Opiate analgesia