Urinary Retention
ABCs
- check vital signs
- acute retention → painful, sudden inability to void + palpable bladder
- chronic retention → painless, incomplete emptying, may present as overflow incontinence or AKI
- bladder scan: confirm retention + estimate volume before catheterization
- review drug chart: anticholinergics, opioids, sympathomimetics, anaesthetic agents
- immediate Urology consult: pelvic/perineal trauma, urethral stricture history, blood at meatus
- life-threatening causes: severe acute prostatitis, spinal cord compression, cauda equina
cauda equina
- new lower-limb weakness or bilateral sciatica
- saddle / perineal sensory loss
- bowel dysfunction or reduced anal tone
- urinary retention with neurological symptoms → urgent MRI / spine review
- see back pain for the full cauda equina screen
do not force a urethral catheter
- suspected urethral injury (pelvic trauma, blood at meatus, high-riding prostate, perineal hematoma) → Urology before any attempt
- catheter does not pass easily: no repeated or forceful attempts. One reattempt with larger or Coude-tip catheter is reasonable, then escalate to Urology
- Urology may place suprapubic catheter or perform cystoscopy-guided catheterization
escalation
- fever/sepsis with retention → acute prostatitis, pyelonephritis, or infected obstructed system; catheterize + antibiotics + shock management if hemodynamically unstable
- gross hematuria or clot retention
- severe pain despite drainage
- large residual drained (especially > 1 L)
- hyperkalemia, AKI, hydronephrosis, solitary kidney
- neurological red flags or suspected cauda equina
- failed or traumatic catheterization → Urology for suprapubic catheter
HPI & examination
- obstructive causes
- BPH, prostate cancer, urethral stricture, stones, clot retention
- constipation / fecal impaction (common, easily missed in elderly/postoperative patients)
- pelvic mass, pregnancy (third trimester)
- neurological causes
- stroke, multiple sclerosis, spinal cord compression, cauda equina syndrome
- diabetic autonomic neuropathy, spinal cord injury
- medications
- ↓ detrusor activity: anticholinergics (1st-gen antihistamines, TCAs, antipsychotics, antiparkinson, antispasmodics), CCBs, NSAIDs
- ↑ sphincter tone: opioids
- sympathomimetics / decongestants: ↑ outlet resistance
- precipitating factors: recent surgery / anaesthesia, immobility, constipation, UTI, excess alcohol, epidural / spinal anaesthesia
- examination
- abdomen: palpable bladder, tenderness
- genital: meatal stenosis, discharge, prepuce retractability
- vaginal exam: pelvic mass
- DRE: prostate size / tenderness, rectal mass, fecal impaction, sphincter tone
- neurological: lower-limb power, reflexes, perineal sensation, gait
workup
- U&E, creatinine ± VBG → AKI, hyperkalemia, dehydration
- urinalysis ± culture → if infection symptoms, fever, or unclear trigger
- CBC, CRP → if infection or sepsis suspected
- PSA → avoid acutely (falsely elevated by retention/catheterization); defer to outpatient
imaging (if indicated)
- renal ultrasound → hydronephrosis, chronic retention, upper-tract dilatation
- CT KUB → stone, malignancy, complex obstruction, unexplained AKI
- MRI spine → neurological cause suspected (cauda equina, cord compression)
management
relieve retention
- insert Foley catheter: 14–16 Fr (male), 12–14 Fr (female)
- drain completely: clamping to decompress slowly is unsupported by evidence; blood-stained urine afterwards (hematuria ex vacuo) is common and self-limiting
- document residual volume
- catheter fails → do not force. One reattempt with larger or Coude-tip catheter is reasonable, then Urology for suprapubic or cystoscopy-guided insertion
post-obstructive diuresis
- suspect if urine output ≥ 200 mL/hr for 2 consecutive hours or > 3 L/24 hr
- monitor vitals, strict input/output, U&E/Mg/PO4 at least every 6–12 h
- replace a proportion of losses, guided by volume status and electrolytes; do not match 1:1 (perpetuates diuresis); let excess fluid clear if volume overloaded
- most is physiological and self-limiting; pathological diuresis (renal concentrating defect) warrants closer monitoring
- address underlying cause
- medication review: stop/reduce offending drugs where safe (anticholinergics, opioids, sympathomimetics)
- constipation / fecal impaction → disimpaction, stool softeners, enemas
- infection → culture and treat if symptomatic; do not treat asymptomatic bacteriuria in catheterized patients. See empiric antibiotics for agent and dose
- AKI / upper-tract obstruction → see anuria / oliguria
- neurological cause → urgent spinal imaging + specialty referral
- BPH-related acute retention
- start alpha-blocker unless contraindicated, e.g. tamsulosin 0.4 mg PO OD
- plan trial without catheter (TWOC)
- evidence supports an alpha-blocker for ~3 days before removal, catheter out ~24 h later
- no guideline fixes these intervals: follow local urology practice
- TWOC fails → long-term catheter or Urology referral for surgical options
disposition
- admit: AKI, sepsis, post-obstructive diuresis, failed catheterization, neurological red flags, large-volume retention (> 1 L)
- discharge with catheter: stable, no AKI/infection, cause identified + reversible → start alpha-blocker, arrange TWOC or Urology follow-up within days
- recurrent/chronic: Urology referral for definitive management
evidence
| source | type |
|---|---|
| EAU 2024 · Urinary Retention and Neuro-Urology ↗︎ | international guideline |
Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.
free the on-call checklist covers the whole shift on one printable page.
studying for the IM exam? the IM Rapid Review covers this in the same format. see the sample chapter.
reviewed Jul 2026updated Sep 2026file complaint/urinary-retention