What is urinary retention?
- The inability to completely empty bladder of urine
- Can be acute or chronic
Define acute urinary retention?
- New onset inability to pass urine
- Subsequently leads to pain and discomfort with significant residual volumes
- Most common in older patients, typically enlarged prostate leading to bladder outflow obstruction
Define Acute-on-chronic urinary retention?
- Patients with chronic retention who enter acute retention
- Deterioration of the underlying pathology
- New cause superimposed on chronic retention
- Minimal discomfort despite large residual volumes
- Risk from post-obstructive diuresis
Describe the causes of acute urinary retention?
- Benign prostatic hyperplasia (most common)
- UTIs, constipation
- Severe pain
- Medications
- Peripheral neuropathy, MS, parkinsons, bladder sphincter dyssynergy
What medications can cause acute urinary retention?
- Opioids
- Anti-muscarinics
- Atropine
- Sympathomimetics
- Epidural anaesthesia
What is Bladder sphincter dysinergy?
- Lack of co-ordination of detrusor muscle conrtaction with urethral sphincter relaxation
- Leads to contraction against a closed sphincter
- Seen with spinal cord pathology or traumatic injury
Clinical features of acute urinary retention?
- Acute suprapubic pain
- Inability to micturate
- UTI symptoms, change to medication worsening voiding LUTS
Signs from a examination of someone with acute urinary retention?
- Palpable distended bladder
- Suprapubic tenderness
- PR examination to assess for prostate enlargement
Investigations into suspected acute urinary retention?
- Post-void bedside bladder scan
- Shows volume of retained urine
- FBC, CRP, U&Es
- CSU (catheterised specimen of urine)
- Patients with high pressure retention:
- US of urinary tract
- Assess for hydronephrosis
- US of urinary tract
Desribe high-pressure urinary retention?
- Retention causing high intra-vascular pressure
- Anti-reflux mechanism of bladder and ureters is overcome and backs up into the upper renal tract
- Leads to hydroureter and hydronephrosis
Describe the management of acute urinary retention?
- Urgent urethral catheterisation
- Measure volume drained post-catheterisation
- Large retention volume patients should be monitored for post-obstructive diuresis
- Treat underlying cause
- Tamulosin for enlarged prostate (alpha receptor blocker)
- Antibiotics for infection
Who is at risk from post-obstruction diuresis?
Those with a retention volume of around 1000ml
Describe post-obstructive diuresis?
- Loss of medullar concentration gradient following retention
- Excess urine produced which can cause worsening AKI
Complications of acute urinary retention
- AKI -> CKD if multiple episodes leads to renal scarring
- UTIs
- Renal stones due to urinary stasis
What receptors provide the main parasympathetic supply to the bladder?
M3 muscarinic receptor
What medication can be trialled fo long-term control as first line in males with acute urinary retention due to BPH?
Tamsulosin
A patient presents with 600ml in AUR and has no evidence of renal impairment of his bloods, after what time period can a TWOC be trialled?
7 days
Define chronic urinary retention?
- Painless inability to pass urine
- Patients with long standing retention
- => significant bladder distension causing desensitisation
- ***Patients who pass small amounts of urine but retain large residual volumes are still classified as having chronic urinary retention
Describe the causes of chronic urinary retention?
- BPH (most common cause in men)
- Urethral strictures, prostate cancer
- In women, pelvic prolapse is a cause
- cystocele, rectocele, uterine prolape
- Peripheral neuropathies, MS, Parkinsons
Clinical features of chronic urinary retention?
- Painless urinary retention
- Associated voiding LUTS (weak stream, hesitancy)
- Overflow incontinence worse at night
- Palpable distended bladder with no/minimal tenderness
Describe the invesitgations for a suspected chronic urinary retention?
- Post-void bedisde bladder scan
- FBC, CRP, U&Es
- Patients with features of high-pressure retention require US
Describe the management of chronic urinary retention?
- High post void volumes (>1L) or high pressure retention
- Long term catheter
- Alternatives: ISC, suprapubic catheter
- Should not undergo Trial WithOut Catheter (TWOC) before definite management is planned
- Definitive management depends on the underlying cause
Describe ISC?
- Intermittent self catheterisation
- For patients with chronic retention who do not want a long-term catheter
- Patients catheterise themselves at regular intervals (4-6hrs)
- Requires good manual dexterity and patient compliance
Complications of chronic urinary retention?
- UTIs and bladder calculi
- Due to prolonged urinary stasis
- Repeat episodes of unmanaged high-pressure retention lead to CKD
