Urinary retention

Question 1

what residual bladder vol. indicates urinary retention

Answer 1

A residual bladder volume >300 mL would confirm acute urinary retention

Question 2

Initial imaging Ix for suspected urinary retention

Answer 2

KUB USS

Question 3

What types of medication causes urinary retention as its common SE

Answer 3

TCAs - e.g. amitriptyline

Question 4

what is the most common cause of urinary retention in older men

Answer 4

BPH - enlarged prostate can obstruct the urethra leading to difficulty passing urine

Question 5

Define urinary retention

Answer 5

urinary retention is an inability to pass urine

Question 6

Urinary retention subtypes

Answer 6

Acute urinary retention
Chronic urinary retention

Question 7

Define Acute urinary retention

Answer 7

a new onset inability to pass urine, which subsequently leads to pain and discomfort, with significant residual volumes.

Question 8

urinary retention complications

Answer 8

1. Post-obstructive diuresis (POD)
2. High-Pressure Urinary Retention (HPUR)

Question 9

Urinary retention causes types

Answer 9

Obstructive causes
Neuro causes

Question 10

Urinary retention obstructive causes

Answer 10

1. BPH: common in older men
2. Urethral stricture: narrowing of the urethra
3. UTIs: closure of the urethral sphincter (esp. in those with already narrowed outflow tracts e.g. BPH)
4. Constipation: compression on the urethra

Question 11

Urinary retention neuro causes

Answer 11

1. peripheral neuropathy (bladder dysfunction due to nerve damage)
2. iatrogenic nerve damage during pelvic surgery
3. upper motor neurone disease (such as Multiple Sclerosis Parkinson’s disease)
4. DSD (detrusor sphincter dyssynergia)

Question 12

Urinary retention Sx

Answer 12

1. Sudden inability to urinate despite a full bladder
2. Acute severe lower abdominal pain & pressure (suprapubic region)
3. Distended bladder
4. Urgent need to urinate but unable to pass urine

Question 13

Urinary retention examination findings

Answer 13

1. Palpable distended bladder
2. Suprapubic tenderness
3. Suprapubic dullness on percussion
4. Enlarged prostate
5. Firm, rigid or tender abdo –> constipation

Question 14

Urinary retention examination

Answer 14

1. abdo examination: look for bladder distention, suprapubic tenderness / dullness, bowels (?constipation)
2. DRE: look for enlarged prostate, ?constipation

Question 15

Urinary retention blood Ix

Answer 15

1. FBC - WCC (?raised)
2. CRP (?raised)
3. U+Es (?electrolyte imbalance), assess kidney functions

Question 16

Urinary retention Mx

Answer 16

1. Urethral catheterisation
2. Measure Urine output

Question 17

what Ix can be done post-catheterisation

Answer 17

Catheterised urine sample: for MC&S

Question 18

High-Pressure Urinary Retention clinical findings

Answer 18

1. Deranged renal functions
2. Hydronephrosis: swelling of the kidney on USS
3. Hydroureter: swelling of the urethra (urine transport tube)
4. > 1000ml residual bladder vol.

Question 19

When would you suspect POD

Answer 19

• > 200 mL/h urine output
• > 1000ml of catheterised urine vol.

Question 20

Choice of catheter for urinary retention w/out haematuria

Answer 20

2-way Foley catheter

Question 21

what receptors are on the PSN of the bladder

Answer 21

M3 muscarinic receptors

Question 22

how does amitriptyline causes urinary retention

Answer 22

Anticholinergic: bind on to the M3 receptors on the bladder - relaxes the bladder –> urine retention

Question 23

Tamsulosin contraindication in BPH

Answer 23

Not to be used in patient with orthostatic hypotension

Question 24

Tamsulosin MoA

Answer 24

Tamsulosin blocks alpha-1 receptors –> vasodilation –> BP drop

Question 25

alternate pharmacological Tx for BPH in patient with low BP

Answer 25

Finasteride

Question 26

when should you suspect high pressure urinary retention