Urinary Retention (obstruction)

Question 1

What is Obstructive Nephropathy?

Answer 1

refers to a problem passing urine that is a result of obstruction along the urinary tract. When it causes an acute reduction in kidney function this is referred to as “postrenal acute kidney injury”.

Question 2

How does Upper Urinary Tract Obstruction Present?

Answer 2

Upper Urinary Tract Obstruction (i.e. ureters)

Loin to groin / flank pain on affected side (result of stretching / irritation of ureter and kidney
Reduced / no urine output
Non-specific symptoms (e.g. vomiting)
Reduced renal function on bloods

Question 3

How does Lower urinary tract obstruction present?

Answer 3

Lower Urinary Tract Obstruction (i.e. bladder / urethra)

Acute urinary retention (unable to pass urine and increasingly full bladder)
Lower urinary tract symptoms (e.g. poor flow, difficulty initiating urination, terminal dribbling)
Reduced renal function on bloods

Question 4

What are upper urinary tract causes?

Answer 4

Upper Urinary Tract

Kidney stones
Local cancer masses pressing on the ureters
Ureter strictures (scar tissue narrowing tube)

Question 5

What are lower urinary tract causes?

Answer 5

Lower Urinary Tract

Benign prostatic hyperplasia (enlarged prostate)
Prostate cancer
Ureter or urethra strictures (from scar tissue)
Neurogenic bladder (no neurological signal telling bladder to contract)

Question 6

What are the complications of obstruction?

Answer 6

Lower Urinary Tract

Benign prostatic hyperplasia (enlarged prostate)
Prostate cancer
Ureter or urethra strictures (from scar tissue)
Neurogenic bladder (no neurological signal telling bladder to contract)

Question 7

Neurological causes of retention?

Answer 7

Autonomic or peripheral nerve (eg, autonomic neuropathy, diabetes mellitus, Guillain-Barré syndrome, pernicious anaemia, poliomyelitis, radical pelvic surgery, spinal cord trauma, tabes dorsalis).
Brain (eg, cardiovascular disease (CVD), multiple sclerosis (MS), neoplasm, normal pressure hydrocephalus, Parkinson's disease).
Spinal cord (eg, invertebral disc disease, meningomyelocele, MS, spina bifida occulta, spinal cord haematoma or abscess, spinal cord trauma, spinal stenosis, spinovascular disease, transverse myelitis, tumours, cauda equina)

Question 8

Drug causes of retention

Answer 8

Anticholinergics (eg, antipsychotic drugs, antidepressant agents, anticholinergic respiratory agents).
Opioids and anaesthetics.
Alpha-adrenoceptor agonists.
Benzodiazepines.
Non-steroidal anti-inflammatory drugs.
Detrusor relaxants.
Calcium-channel blockers.
Antihistamines.
Alcohol.

Question 9

Retention Examination

Answer 9

General - look for fever and signs of infection and systemic illness.
Abdominal - a tender enlarged bladder with dullness to percussion well above the symphysis pubis, often almost to the level of the umbilicus.
Genitourinary:
In men, look for phimosis or meatal stenosis, as well as urethral discharge and genital vesicles.
In women, look for evidence of:
Vulval or vaginal inflammation or infection.
Cystocele, rectocele or uterine prolapse.
Pelvic mass (eg, retroverted gravid uterus, uterine fibroid, gynaecological malignancy).
Per rectum (PR) - check anal tone, prostatic size, nodules, tenderness, etc and exclude faecal impaction.
Neurological - look for evidence of prolapsed disc or cord compression by checking lower limb power and reflexes as well as perineal sensation.

Question 10

How does chronic urinary retention present?

Answer 10

Partial obstruction. Generally painless. May be associated with LUTS like frequency, urgency, or overflow incontinence.

Question 11

What are complications of chronic retention?

Answer 11

Hydronephrosis, renal impairment including chronic kidney disease, bladder detrusor hypertrophy and diverticula, acute-on-chronic retention

Question 12

What investigations for retention?

Answer 12

Bladder ultrasound: complete inability to pass urine (acute) or post-void residual volume > 300ml (chronic) is diagnostic.

Urinary catheterisation (volume of urine): document residual urine (RU) and relief of discomfort/ pain after bladder drainage.

Intermittent self- catheterisation: is an option prior to indwelling catheter in suitable men with chronic urinary retention.

Question 13

Acute retention management

Answer 13

Initial Management :
Urethral catheterisation
Suprapubic catheter ( SPC) 
Late Management:
Treating  the underlying cause

** Bladder drainage in chronic retention should be done under slow rate to avoid sudden decompression—> hematuria