Normal voiding has two phases ^[1]:

Why this matters: Each requirement for normal voiding can fail. When storage fails → incontinence. When emptying fails → retention. This is the framework for understanding ALL lower urinary tract pathology.

During storage ^[1]:

• Myelinated Aδ sensory fibres send low-level afferent signals (vesicosympathetic 'storage' reflex)
• Sympathetic pathway: ACTIVE (+ve)
• Parasympathetic pathway: INHIBITED (-ve)
• Somatic pathway: ACTIVE (+ve)
• Results in:
  • Detrusor relaxation (β3-adrenergic)
  • Internal urethral sphincter contraction (α1-adrenergic)
  • External urethral sphincter contraction (nicotinic)

Why this works: Low-level bladder filling activates sympathetic tone via a spinal reflex. The bladder relaxes to accommodate urine (receptive relaxation following Laplace's Law: T = P×R / 2d), while both sphincters contract to maintain continence. The parasympathetic drive to the detrusor is actively suppressed.

During voiding ^[1]:

• Higher level of afferent firing signals to PMC + "OK" signal from cerebral cortex
• The on-off switch is 'flipped' — PMC sends signals to:
  • Sympathetic: INHIBITED (-ve)
  • Parasympathetic: ACTIVE (+ve)
  • Somatic: INHIBITED (-ve)
• Results in:
  • Detrusor contraction (M3 muscarinic)
  • Internal urethral sphincter relaxation
  • External urethral sphincter relaxation

Voiding reflex pathway ^[1]: Critical level of afferent activity from tension receptors in bladder → PMC (+ cortical input) → three simultaneous outputs:

1. Activation of sacral parasympathetic efferent to bladder → Contraction of detrusor
2. Activation of sacral parasympathetic to urethra → Relaxation of urethral smooth muscle
3. Inhibition of somatic pathway to sphincter → Relaxation of striated sphincter → Voiding

In spinal cord injury (SCI), the descending control from PMC is interrupted ^[1]:

• The detrusor contracts BUT the sphincter contracts simultaneously (should relax)
• This is called Detrusor Sphincter Dyssynergia
• Results in extremely high intravesical pressures → upper tract damage

Why DSD occurs: The PMC normally coordinates detrusor contraction WITH sphincter relaxation as a single package. When the spinal cord is damaged above the sacral segments (suprasacral lesion), local sacral reflexes can still trigger detrusor contractions, but the inhibitory signal to the sphincter (which comes from the PMC) cannot get through. Both muscles fire at once.

Two types of retention ^[1]:

AROU is defined as "sudden inability to pass urine" — a common reason for hospital admission in Urology. Can occur in both males and females ^[1].

Incidence in men ^[1]:

• ~7 per 1,000 men per year
• Cumulative 4-year probability: 3%
• Over 5 years: 10% of men in their 70s and ~30% of men in their 80s will experience AROU

Risk factors for male AUR (Olmsted County Study) ^[1]:

• Increasing age
• Increasing prostate size
• Increasing BPH symptoms
• Decreasing maximal urine flow rate

Incidence in women ^[1]:

• ~3 per 100,000 per year (much rarer than in men)
• Bladder outlet obstruction less common
• A proportion has detrusor underactivity (DUA)

Three mechanisms of AROU ^[1]:

Precipitating factors of AROU ^[1]:

• Constipation
• UTI
• Anaesthesia / analgesia
• Immobility
• Painful peri-anal conditions (e.g. thrombosed haemorrhoids, perianal abscess)
• Excessive fluid intake (esp. alcohol)
• Drugs:
  • With anticholinergic S/E: antipsychotic, antispasmodics, H1 antihistamines, antidepressants, ipratropium, disopyramide
  • With sympathomimetic S/E: cold medications, MDMA

Important distinction ^[1]: Urinary retention ≠ anuria or oliguria Causes of no urine production:

• Pre-renal ARF: dehydration, shock
• Renal ARF: drug-induced, ATN, nephritis

In retention, the kidneys ARE making urine — it just can't get out. The bladder is full and distended. In anuria/oliguria, the bladder is empty because the kidneys aren't producing urine.

BOO is more common in men ^[1]:

Symptoms ^[1]:

• Weak stream
• Hesitancy
• Intermittency
• Terminal dribbling
• Incomplete emptying
• Overflow incontinence
• Lower abdominal distension
• Uraemic symptoms

These are primarily voiding (obstructive) symptoms. Remember the mnemonic: DISH = Dribbling, Intermittency, Straining, Hesitancy ^[3].

Complications progress from bladder → upper tract ^[1]:

• Retention of urine — acute or chronic
• Recurrent UTI
• Formation of bladder calculi
• Hydroureter and hydronephrosis
• Renal impairment / ARF (Obstructive uropathy)

Why this progression occurs: Chronic obstruction → increased residual urine → stasis → UTI and stone formation. Chronically elevated intravesical pressure → transmitted backwards to ureters and kidneys → hydroureter/hydronephrosis → if bilateral and persistent → obstructive nephropathy → renal failure.

BPH is a histological diagnosis: benign proliferation of both glandular epithelium and stromal tissue in the transitional zone of the prostate ^[3]. It is androgen-dependent, driven primarily by dihydrotestosterone (DHT), which is converted from testosterone by 5α-reductase within the prostate.

BPH causes obstruction through two components ^[3]:

• Static component: Physical enlargement of the prostate compresses the urethra (mediated by DHT → stromal hyperplasia) → target of 5α-reductase inhibitors (finasteride, dutasteride)
• Dynamic component: Smooth muscle contraction in the prostate/bladder neck via α1 receptors → target of α1-blockers (tamsulosin, alfuzosin)

Organized by level ^[3]:

A validated 7-question tool quantifying LUTS severity ^[2]:

• 4 voiding symptoms: incomplete emptying, intermittency, weak stream, straining
• 3 storage symptoms: frequency, urgency, nocturia
• Plus 1 quality-of-life question
• Score interpretation: Mild 1-7, Moderate 8-19, Severe 20-35
• Used to guide treatment and monitor response — NOT a diagnostic tool

*Tamsulosin, alfuzosin, doxazosin are more uroselective α1A blockers ^[3].

• TURP (Transurethral Resection of Prostate) — gold standard surgical treatment
• Indications for surgery: failed medical therapy, recurrent AROU, recurrent UTI, bladder stones, renal impairment from BOO, recurrent haematuria
• Complications: TUR syndrome (hyponatraemia from irrigation fluid absorption), retrograde ejaculation, urethral stricture, bladder neck stenosis

History 1 ^[1]:

• Confirm urinary retention — check first catheterized urine volume
• Painful vs painless retention
• First episode or recurrent
• Preceding LUTS
• Other BPH complications: gross haematuria, UTI (fever/dysuria), bladder/urethral stone (strangury), renal impairment (uraemic symptoms)

History 2 ^[1]:

• Precipitating factors of AROU
• Lower limb weakness/numbness + overflow incontinence/faecal incontinence → SUSPECT ACUTE SPINAL CORD COMPRESSION
• Constitutional symptoms / multiple bone pain → Suspect metastatic CA prostate

History 3 ^[1]:

• Medications: BPH medications (alpha blockers / 5-ARI), anticholinergics etc.
• Previous prostate surgery (e.g. TURP) or urethral instrumentation
• History of STD especially gonococcal/non-gonococcal urethritis (→ urethral stricture)
• History of CVA / Parkinsonism / Spinal surgery (→ neurogenic bladder)

Physical Examination 1 ^[1]:

• Vital signs: Is the patient septic? Is the patient uraemic?
• Abdominal exam: Palpable urinary bladder (if not yet catheterized), any phimosis
• Urethral catheter output: any gross haematuria?

Physical Examination 2 ^[1]:

• Digital Rectal Examination (DRE):
  • Anal tone and peri-anal sensation (test sacral nerve integrity)
  • Prostate estimated size
  • Clinical features suspicious of prostate cancer (hard, nodular, obliterated sulcus)
  • Prostate tenderness (prostatitis)
  • Faecal impaction (precipitating cause)
  • Any painful peri-anal conditions
• Lower limb neurological deficit

Management 1 — Immediate decompression of bladder ^[1]:

• Urethral catheterization (first line)
• Suprapubic catheterization (SPC) (if urethral route fails or contraindicated)

SPC Indications ^[1]:

• Failed urethral catheterization
• History of urethral trauma (e.g. straddle injury)

SPC Contraindications ^[1]:

• Non-distended bladder
• Uncorrected bleeding tendency
• Known/suspected urothelial cancer

SPC Complications ^[1]:

• Bowel perforation
• Rectal injury (overshoot)
• Haematuria

Investigations ^[1]:

• CBP (complete blood picture)
• L/RFT (liver and renal function tests)
• CSU × C/ST (catheter specimen of urine for culture and sensitivity)
• KUB (plain X-ray of kidneys, ureters, bladder)
• No PSA — likely falsely elevated (in the acute setting with catheter in situ, manipulation, UTI)

• α1-blocker vs 5-ARI: α1-blockers work within days (quick relief); 5-ARI takes 6-12 months (for large prostates)
• Uroflowmetry vs Pressure-flow study: Uroflowmetry = screening (Qmax only); Pressure-flow = diagnostic (Qmax + Pdet)
• IPSS vs urodynamics: IPSS = symptom severity tool; Urodynamics = objective diagnosis of BOO
• Urethral cath vs SPC: SPC only if urethral cath fails or urethral trauma; never SPC into non-distended bladder

Stem: "A 60-year-old gentleman with good past health presented to you with LUTS that are bothersome to him. Physical examination revealed no remarkable findings except an enlarged prostate to 50 ml with normal consistency and no suspicious nodules. Which of the following investigations can diagnose underlying bladder outlet obstruction in this gentleman?"

Options:

• A. Filling cystometry
• B. International prostate symptom scores (IPSS) measurement
• C. Pressure flow study ✓
• D. Uroflowmetry

Answer: C. Pressure flow study

Rationale: BOO is a urodynamic diagnosis defined by low uroflow rate + high detrusor pressure. Only pressure-flow study measures both parameters. Uroflowmetry (D) measures flow only and cannot distinguish BOO from detrusor underactivity. IPSS (B) is a symptom questionnaire, not diagnostic. Filling cystometry (A) assesses storage function, not voiding obstruction.

Q22 Stem: "A 68-year-old man was recently found with elevated PSA of 6.7 ng/mL. He received a transrectal ultrasound-guided prostate biopsy this morning. He came to the A&E at night with severe LUTS. Temperature 38.2°C, raised WBC and neutrophils. Bedside USG showed ~500 mL of urine."

Answer: A. Acute prostatitis

Rationale: Post-TRUS biopsy + fever + LUTS + raised inflammatory markers = acute prostatitis. This is a known complication of prostate biopsy. The 500 mL residual indicates retention precipitated by prostatic swelling/infection.

Q23 Stem: "A 73-year-old woman with osteoporosis was hit by a bicycle, sharp low back pain, rested in bed with NSAIDs for several days. Progressive difficulty urinating. Bladder upper border 5 cm above pubic symphysis."

Answer: E. Medications side effect (OR F. Neurologic impairment — depends on mark scheme interpretation)

Rationale: Immobility + NSAIDs + possible spinal injury → retention. The combination of bed rest, analgesics (both opioids and potentially anticholinergic co-prescriptions), and possible spinal trauma makes medication side effect the most testable answer in this EMQ context, though neurological impairment from vertebral fracture with cord/nerve compression is also plausible.

Q24 Stem: "A 75-year-old man came to A&E with retention and incontinence for half a day. Progressive difficulty urinating and increased nocturia for many years, never sought treatment. Could not urinate this morning but had continuous leakage."

Answer: B. Benign prostatic hyperplasia

Rationale: Long history of progressive LUTS (hesitancy, nocturia) in an elderly man who now presents with acute-on-chronic retention with overflow incontinence. Classic BPH presentation with decompensation.

Stem: "An 80-year-old man complains of long standing LUTS, including hesitancy, frequency and needing to strain and sense of incomplete emptying. His family finds he always wets the bed at night. What is the MOST LIKELY cause of his incontinence?"

Options:

• A. Functional incontinence
• B. Overflow incontinence ✓
• C. Stress incontinence
• D. Urge incontinence

Answer: B. Overflow incontinence

Rationale: Long-standing obstructive LUTS (hesitancy, straining, incomplete emptying) → chronic retention → the bladder is chronically full and overflows → bed-wetting = overflow incontinence. Urge incontinence (D) would present with sudden urgency then leakage, not chronic obstructive symptoms. Stress incontinence (C) occurs with cough/straining and is more common in women. Functional incontinence (A) requires physical/cognitive impairment preventing the patient from reaching the toilet.

Stem: "80-year-old gentleman admitted via A&E with gross haematuria. On-and-off painless haematuria for 3 months. Weight loss 5 kg. Presented with passage of clots and inability to void. Chronic smoker. Palpable bladder. DRE: benign 50g prostate."

Q3 (Section 2): Name two immediate urological treatments for this patient. (4 marks)

Markscheme:

1. Urethral catheterization (with three-way catheter for clot evacuation)
2. Continuous bladder irrigation (to prevent re-clotting)

Rationale: This is clot retention — one of the listed causes of AROU in the lecture. The inability to void is because blood clots are blocking the bladder outlet. A three-way catheter allows both drainage and continuous irrigation.

Stem: "Which of the following statements BEST describes stress urinary incontinence?"

Options:

• A. It is a more common problem in female. ✓
• B. It is associated with frequent urinary tract infection.
• C. It is more severe when patient is sleeping at night.
• D. It is typically associated with a strong sense to void followed by involuntary loss of urine.

Answer: A

Rationale: Though this is about stress incontinence rather than AROU, it's relevant to differentiating types of incontinence. Option D describes urge incontinence. Option B describes overflow incontinence (chronic retention). Option C would suggest nocturnal polyuria or overflow.

Stem: "A 70-year-old man has a history of chronic neck pain. Sustains a fall causing hyperextension of his neck. X-rays show multiple osteophytes and narrowing of spinal canal. MRI shows hyperintense signals on T2 within cervical spinal cord. What is MOST LIKELY on clinical examination?"

Options:

• A. Clumsy hand movement ✓
• B. Foot drop
• C. Loss of proprioception in lower limbs
• D. Urinary retention

Answer: A. Clumsy hand movement

Rationale: This is central cord syndrome (hyperextension injury in cervical spondylosis → central cord haemorrhage/oedema). Central cord syndrome classically affects upper limbs > lower limbs (because upper limb tracts are more centrally located). Urinary retention (D) can occur but is NOT the most likely finding — clumsy hand movement from upper limb weakness/UMN signs is more characteristic. This question tests the nuance that not all spinal cord pathology presents with urinary retention first.