Urology: urinary retention

Question 1

What is acute urinary retention?

Answer 1

Medical emergency characterised by the abrupt development of the inability to pass urine

Question 2

What investigations would you do for acute urinary retention?

Answer 2

• Bedside : DRE, Urinanlysis
• Bladder scan, post void residue.
• May also want to do USS kidney for any hydronephrosis.
• Serum U&Es and creatinine should also be checked to assess for any kidney injury.
• A FBC and CRP should also be performed to look for infection
• Rectal and neuro exam
• Pelvic exam in female

Question 3

How does Acute urinary retention present?

Answer 3

• Painful
• Acute suprapubic pain
• unable to urinate
• Acute confusional state

PMH of uti, change in meds or worsening LUT sx.
Pt has a palpable distended bladder and tenderness suprapubically on examination

Question 4

How does Chronic urinary retention present?

Answer 4

Painless!! Has voiding LUT sx - weak stream, hesitancy, overflow incontinence that is worse at night. Pt has palpable distended bladder but no/minimal suprapubic tenderness.

Question 5

What investigations would you do for urinary retention?

Answer 5

• PR exam - enlarged prostate or constipation.
• Post-void bladder scan.
• Need to do routine bloods.
• Take specimen of urine from catheter to check for infection.
• Do an USS for any associated hydronephrosis

Question 6

How is acute urinary retention managed?

Answer 6

• Remove precipitant
• Immediate catheter needed.
• Measure volume post catheterisation. Monitor for post-obstructive diuresis.
• TWOC

Question 7

What are complications of acute urinary retention?

Answer 7

AKI - can lead to CKD.
Risk of UTI and stones due to stasis of urine.

Question 8

How is chronic urinary retention managed?

Answer 8

Long term catheter and/or self catheter if an option. Monitor for post-obstructive diuresis.

Question 9

What are complications of chronic urinary retention?

Answer 9

UTI, stones in bladder, CKD

Question 10

Causes of acute urinary retention ?

Answer 10

In men: BPH
Urethral strictures, constipation, masses, UTI, neuro causes
Anti-cholinergic medication, antihistamines, opioids, post-partum in women

Question 11

What is post obstructive diuresis?

Answer 11

Kidney’s increase diuresis due to loss of medullary conc gradient in urinary retention- may take time to re-equiliberate

Volume depletion and worsening of AKI

Question 12

What medications can cause acute urinary retention?

Answer 12

• Anticholinergics,
• tricyclic antidepressants,
• antihistamines,
• opioids and
• benzodiazepines.

Question 13

When does acute urinary retention occur in women?

Answer 13

often occurs postoperatively and in women postpartum usually secondary to the other RF

Question 14

How to confirm a pt is in acute urinary retention?

Answer 14

• bladder ultrasound should be performed.
• volume of >300 cc confirms the diagnosis
• but if the history and examination are consistent, with an inconsistent bladder scan, there are causes of bladder scan inaccuracies and hence the patient can still have acute urinary retention.

Question 15

How to manage acute urinary retention?

Answer 15

• decompressing the bladder via catheterisation
• Urinary catheterisation can be performed in patients with suspected acute urinary retention, and the volume of urine drained in 15 minutes measured.
• A volume of <200 confirms that a patient does not have acute urinary retention, and a volume over 400 cc means the catheter should be left in place. In between these volumes, it depends on the case.
• Further investigation should be targeted by the likely cause. In reversible causes such as UTI, resolution with treatment is sufficient and further investigation is not necessary.
• Men not diagnosed by BPH should be further evaluated by a urologist,
• Patients with neurological symptoms should be evaluated by a neurologist
• women with gynaecological symptoms by a gynaecologist.
• Where no likely cause is identified, patients should be evaluated by a urologist for anatomical and urodynamic causes.

Question 16

What are the types of chronic urinary retention?

Answer 16

High pressure retention
* impaired renal function and bilateral hydronephrosis
typically due to bladder outflow obstruction

Low pressure retention
* normal renal function and no hydronephrosis

Question 17

What is decompression haematuria?

Answer 17

occurs commonly after catheterisation for chronic retention due to the rapid decrease in the pressure in the bladder. It usually does not require further treatment.

Question 18

How to assess for post-obstructive diuresis?

Answer 18

• Worried about hyponatraemia
• Assess fluid balance
• Consider weighing the patient every day
• Daily U&Es

Question 19

What is complication of relieveing urinary retention?

Answer 19

post obstructive diureiss

Question 20

what is post obstructive diuresis?

Answer 20

Development of post obstructive diuresis occurs when there’s >200ml/hr for 2 consecutive hours.

Post-obstructive diuresis can occur after the acute drainage and decompression of a distended bladder and results in prolonged polyuria with excessive loss of both salt and water.

Question 21

How is post obstructive diuresis managed?

Answer 21

• Urine osmolarities should be taken as this will determine management.
• Iso-osmolar urine indicated the kidneys do not need to concentrate the urine and is consistent with physiological diuresis and it generally self-limiting.
• Hyper-osmolarity indicates the kidneys are concentrating urine so post-obstructive diuresis has, or is resolving.
• Hypo-osmolarity indicates salt wasting and the inability for the kidneys to concentrate urine. This is pathological and patients should have fluids replaced like for like.