Urinary retention

Urinary retention is the inability to voluntarily empty the bladder. The cause can be either mechanical (e.g., benign prostatic hyperplasia, tumors, urethral strictures) or functional (e.g., detrusor underactivity due to peripheral neuropathy, anticholinergic drugs). Patients with acute urinary retention (AUR) present with a sudden, painful inability to void and a tender, distended bladder on palpation. Patients with chronic urinary retention (CUR) are typically unable to void completely but do not experience pain. AUR is usually diagnosed clinically and is considered a urological emergency. Therefore, urgent bladder catheterization should precede diagnostics. Diagnostics include renal function tests to assess for renal damage (obstructive nephropathy) and ultrasound of the kidneys, ureter, and bladder to identify the underlying cause and possible complications (e.g., hydroureteronephrosis). Further evaluation depends on the patient history and physical examination. Treating the underlying cause (e.g., with alpha blockers and/or TURP for benign prostatic hyperplasia) is essential to prevent recurrence and complications of urinary retention (e.g., UTI, obstructive nephropathy).

Mechanical bladder outlet obstruction ^[1][2]

Bladder obstruction

• Bladder neck obstruction
  • Bladder calculi
  • Bladder cancer
  • Urinary bladder tamponade
• Bladder injuries
  • Blunt abdominal trauma
  • Pelvic fractures
  • Penetrating trauma
  • Iatrogenic: transurethral or pelvic surgery

Urethral obstruction

• Enlarged prostate gland
  • Benign prostatic hyperplasia (most common)
  • Prostate cancer
  • Acute prostatitis (rare)
• Urethral narrowing
  • Urethral stricture
  • Posterior urethral valves
  • Urethral carcinoma
  • Urethritis
  • Meatal stenosis (rare)
  • Phimosis and paraphimosis
  • Urethral injury (e.g., urethral transection)

Extrinsic obstruction

• Anterior vaginal wall prolapse (e.g., cystocele, urethrocele)
• Pelvic mass (e.g., malignancy, fibroids, endometriosis)
• Rectal mass
• Fecal impaction

Functional bladder outlet obstruction

Neurogenic lower urinary tract dysfunction (neurogenic bladder) ^[3][4][5]

Neurogenic lower urinary tract dysfunction is caused by disruption in the innervation of the detrusor and/or urethral sphincter and is commonly classified by anatomical location.

• Suprasacral spinal cord lesion: spinal cord lesion at or above L1 → detrusor-sphincter dyssynergia with simultaneous contractions of the detrusor muscle and involuntary activation of the urethral sphincter → urinary retention and/or urge incontinence (spastic neurogenic bladder)
  • Spinal cord compression (e.g., spinal disc herniation, spinal epidural abscess, tumor, trauma)
  • Congenital anomalies of the spinal cord (e.g., meningomyelocele, spina bifida)
  • Other conditions involving upper motor neurons (e.g., multiple sclerosis, transverse myelitis)
• Sacral or infrasacral lesions: peripheral nerve damage or spinal cord lesion below L1→ detrusor underactivity with normal or reduced urethral sphincter tone → urinary retention and overflow incontinence (flaccid neurogenic bladder)
  • Lesions involving the conus medullaris or cauda equina (e.g., due to trauma, tumor, infection)
  • Damage to pelvic splanchnic nerves (e.g., due to diabetic autonomic neuropathy, pelvic trauma, pelvic radiation)
• Suprapontine lesion: brain lesion above the pons → disruption in the inhibition of the pontine micturition center → involuntary detrusor contractions → urinary incontinence without urinary retention
  • Cerebrovascular disease
  • Neurodegenerative disease (e.g., Parkinson disease, dementia)
  • Other brain lesions (e.g. tumors)

Drug-induced urinary retention ^[1][6]

• Due to drugs that decrease detrusor activity, e.g.:
  • Drugs with anticholinergic effects; (e.g., first-generation antihistamines, tricyclic antidepressants, antipsychotics, antiparkinson agents, antispasmodics)
  • Calcium channel blockers
  • NSAIDs
• Due to drugs that increase urethral sphincter tone, e.g.:
  • Sympathomimetics (e.g., phenylephrine, pseudoephedrine)
  • Opioids

Other

• Primary bladder neck obstruction: an idiopathic functional disorder characterized by failure of the bladder neck to open completely during micturition ^[7]
• Postoperative urinary retention
• Postpartum urinary retention

Approach ^[1][2]

• Confirm acute urinary retention.
  • Palpable bladder on physical examination
  • And/or distended bladder on POCUS or bladder scanner
• Perform urgent bladder catheterization.
  • Urethral catheterization with a Foley catheter
  • In male patients, consider coude catheter placement if the Foley catheter fails.
  • If urethral catheterization fails, consult urology and consider suprapubic catheterization.
• Obtain initial diagnostics for urinary retention (i.e., urinalysis, urine culture, BMP).
• Perform additional diagnostics as indicated.
• Initiate treatment of the underlying cause, e.g., pharmacotherapy for BPH. ^[10]

In patients with pelvic or perineal trauma or a prior history of urethral strictures, consider immediate urology consult before attempting bladder catheterization. ^[1]

Rapid and complete bladder decompression is recommended for all patients with AUR, as gradual decompression has not been shown to prevent complications. ^[2][11]

Disposition ^[1][2]

• Consider hospital admission for patients with significant comorbidities, neurological deficits, obstructive nephropathy, or UTI.
• Discharge otherwise healthy patients with an indwelling catheter and arrange an outpatient voiding trial 3–7 days later. ^[2]
• Refer patients to urology within 2–3 weeks if: ^[1]
  • Voiding trial is unsuccessful
  • Lower urinary tract symptoms (e.g., hesitancy) were present prior to AUR

If clinical features of AUR are present, perform urgent bladder catheterization before obtaining diagnostic studies. ^[1][2]

Initial diagnostics ^[1][2]

• Bedside imaging: to confirm urinary retention
  • Bladder scanner
  • Bladder POCUS
• Laboratory studies
  • Urinalysis and urine culture: to evaluate for UTI, hematuria, glycosuria, and crystals
  • Basic metabolic panel: to evaluate for obstructive nephropathy and electrolyte abnormalities

Additional diagnostics ^[1]

Additional diagnostics should be obtained in consultation with urology to confirm the diagnosis, determine the etiology of urinary retention, and rule out differential diagnoses.

• Laboratory studies, e.g.:
  • HbA1c for suspected diabetic neurogenic bladder
  • Serum PSA levels for suspected prostate cancer ^[12]
• Imaging, e.g.:
  • Renal and bladder ultrasound to evaluate for hydroureteronephrosis, BPH, and bladder calculi
  • Transrectal ultrasound to evaluate for prostate cancer
  • Pelvic ultrasound and/or CT abdomen and pelvis to evaluate for extrinsic bladder neck compression
  • MRI brain and/or spine to evaluate for neurological causes
  • Cystoscopy with urine cytology for suspected bladder cancer
  • See also “Imaging techniques in urology.”
• Urodynamic studies, e.g., uroflowmetry: to assess bladder function

Treatment of the underlying cause is indicated for AUR and CUR. For immediate management of AUR and urgent bladder decompression, see “Initial management of acute urinary retention.”

Mechanical bladder outlet obstruction

• Enlarged prostate gland
  • Benign prostatic hyperplasia: treatment of BPH (e.g., alpha blockers, TURP)
  • Prostatitis: empiric antibiotics for prostatitis (e.g., ciprofloxacin)
  • Prostate cancer: management of prostate cancer
• Urethral narrowing: Refer to urology for management (e.g., meatotomy for meatal stenosis, balloon dilation for urethral stricture).
• Other obstructive etiologies: : See “Treatment of urinary tract obstruction.”

Functional bladder outlet obstruction

• Neurogenic bladder ^[5][13][14]
  • Storage dysfunction
    • Behavioral therapy: bladder training with timed voiding
    • Pharmacotherapy
      • Antimuscarinic agent: reduces neurogenic detrusor overactivity
      • Desmopressin: temporarily reduces urine production to manage nocturia
  • Voiding dysfunction
    • Intermittent self-catheterization 4–6 times a day with a 12–14 Fr catheter
    • Pharmacotherapy: alpha blockers (e.g., prazosin)
  • Further management may include:
    • Minimally invasive interventions
    • Surgical management ^[15]
• Drug-induced urinary retention: Discontinue or substitute the precipitating drug.
• Postoperative urinary retention: See “Postoperative urinary retention.”
• Primary bladder neck obstruction: Refer to urology for management (e.g., with alpha blockers, surgical incision of the bladder neck).

Complications of urinary retention

• Acute urinary retention: renal failure (acute kidney injury or obstructive nephropathy)
• Chronic urinary retention
  • UTI
  • Vesicoureteric reflux → hydronephrosis → renal failure
  • Urolithiasis
  • Overflow incontinence

Complications of bladder decompression ^[2]

Complications of bladder decompression via catheterization are rare and usually self-limiting.

Postobstructive diuresis ^[16]

• Definition: a polyuric state resulting from the rapid renal elimination of accumulated water and electrolytes after relief of urinary tract obstruction
• Etiology: typically occurs following relief of bladder outlet obstruction or bilateral ureteral obstruction
• Diagnostics
  • > 200 mL/hour urine produced for 2 hours
  • OR > 3 L urine produced in 24 hours
• Management
  • Self-limited; lasts ∼ 24 hours
  • Encourage oral hydration.
  • Consider admission for IV fluids if patients are unable to orally hydrate.
• Complications: dehydration, electrolyte imbalance, hypovolemia

Other complications of decompression

• Hematuria ^[11]
• Transient hypotension

We list the most important complications. The selection is not exhaustive.