Acute urinary retention

Introduction

• Most commonly BPH +- precipitating factors inducing bladder outlet obstruction
• 25% of men with acute urinary retention have prostate cancer (the majority of which are undiagnosed)

Causes

• Male
  • Obstruction – BPH, prostate cancer, phimosis, paraphimosis, meatal stenosis, urethral strangulation
  • Infection – Prostatitis
• Female
  • Obstruction – Cystocoele, ovarian tumor, uterine tumor
  • Operative – Incontinence surgery
  • Infection – PID

Causes

• Obstructive – BPH, urethral stricture, bladder calculi, bladder neoplasm, foreign body
• Neurogenic – MS, Parkinson’s, Brain tumors, stroke, cauda equina, metastatic spinal cord lesions, IV disc lesions, neuropathy, DM, pelvic surgery nerve injury or post-operative retention
• Trauma – Urethral/bladder/spinal cord injury
• Extraurinary – Pelvic abscess, pelvic mass, faecal impaction,  AAA
• Psychogenic – Psychosexual stress, acute anxiety
• Infection – Cystitis, genital herpes
• Epidural anaesthesia
• Pharmacological (see over)

Pharmacological causes

• Sympathomimetics
• Antidepressants – TCA, SSRI
• Antiarrhythmics – Disopyramide, flecainide, quinidine, procainamide
• Anticholinergics/antispasmodics – Atropine, scopolamine, homatropine, hyoscine, glycopyrrolate, oxybutynin
• Anaesthetic agents
• Antiparkinsons – Benztropine, amantadine, levodopa, bromocriptine
• Hormonal – Progesterone, oestrogen, testosterone
• Antipsychotics – Haloperidol, chlorpromazine, prochlorperazine, clozapine, risperidone, ziprasidone
• Antihistamines – Diphenhydramine, promethazine, cyproheptadine
• Antihypertensives – CCB’s, hydralazine, Beta-blockers
• Analgesics – Opioids, NSAIDs
• Muscle relaxants – Diazepam, baclofen

Assessment

History

• Prostatism, incontinence, previous BOO
• Spinal cord/neuro history
• Medication history

Exam

• Full abdominal, genital exam including pelvic and PR
• Complete neurological examination

investigations

• Bladder volume on bedside USS
• Check FBC, U&E (vast majority are low pressure without hydroureter/hydronephrosis/renal impairment
• +- Ix of underlying cause

Treatment

• Urethral catheterisation
  • 14-18Fr initially and if fails:
    • Use firm angulated Coude catheter with tip pointing anteriorly
    • If produces gross blood, deflate balloon, remove catheter and do not re-insert (false passage)
  • If gross haematuria – use 20-24Fr triple lumen
  • Do not attempt insertion if recent operative intervention before discussing with surgeon

Post-obstructive diuresis

• Defined as >200mL/hr for 2 hours or >3000mL/24 hours
• Monitor for 4 hours for >200mL/hr above fluid inputs and after initial drainage
• Pathophysiology
  • Results from renal inability to concentrate urine
  • Potentially fatal
  • Reduced expression of tubular transport proteins (ADH-sensitive AQP2)
  • Washout of medullary concentration gradient
    • Requires adequate vascular supply and urinary tubular flow to exist
  • Lessened ADH sensitivity
  • Ischaemic damage to juxtamedullary nephrons
• Treatment
  • Generally, replacement of 75% of ongoing losses with either oral fluid intake or isotonic saline with close monitoring of serum Na and K is sufficient to prevent complications
  • Complicating factors such as co-existing hyponatraemia and rapid resolution makes for a more difficult treatment protocol
  • Desmopressin
    • Despite the apparent reduced sensitivity to ADH of post-obstructive nephrons, there are plenty of case reports showing effective use of desmopressin in slowing free water loss and preventing rapid resolution of hyponatraemia
    • Requires expert endocrinological and renal input to be done correctly

Spontaneous vs. precipitated

• Spontaneous is due to BPH alone with no other precipitant
  • Higher rates of recurrence (15 vs 9%) and surgery (75 vs. 26%)
  • Typically provide with leg bag, educate, start alpha-blocker (doubles rate of successful TOV) and arrange urology f/u in 3-7 days
• Precipitated is BPH + precipitants
  • Need to cease precipitant and may be able to successfully TOV in ED
• Can treat urgency or bladder spasm associated with IDC with oxybutynin 2.5mg PO TDS (risk of anticholinergic)
• Clot retention needs admission

Last Updated on June 24, 2024 by Andrew Crofton