Urinary Tract Obstruction Flashcards
What is the definition of acute urinary retention?
Painful inability to void with a palpable and percussible bladder
How much do residuals vary in acute urinary retention?
500ml to >1L depending on time lag in seeking medical attention
What is the main risk factor for acute urinary retention?
BPO
Can also occur independently of BPO
-(e.g. UTI, urethral stricture, alcohol excess, post-op causes, acute surgical or medical problems)
For people with BPO when can acute urinary retention occur?
Spontaneously (i.e. natural progression of BPO)
Triggered by an unrelated event (e.g. constipation, alcohol excess, post-op causes, urological procedure)
What is the immediate treatment of acute urinary retention?
Catheterisation (either urethral or suprapubic)
Will feel better straight away
What are the complications of catheterisation in acute urinary retention?
UTI
Post decompression haematuria
Pathological diuresis
Renal failure
Electrolyte abnormalites
After catheterisation in acute urinary retention what is the next step?
Treat underlying trigger if present.
If no renal failure, start alpha blocker immediately and remove catheter in 2 days (60% will void successfully);
-If fail to void, recatheterise and organise TURP (after 6 weeks)
What is the definition of chronic urinary retention?
Painless, palpable and percussible bladder after voiding
How much do residuals vary in chronic urinary retention?
patients often able to void but with residuals ranging from 400ml to >2L depending on stage of condition (i.e. wide spectrum)
What are the main aetiological factors in chronic urinary retention?
Detrusor underactivity which can be primary (i.e. primary bladder failure) or secondary (i.e. due to longstanding BOO, such as BPO or urethral stricture)
How does chronic urinary retention present?
LUTS
Or complications:
-UTI, bladder stones, overflow incontinence, post-renal or obstructuve renal failure) or incidental finding
When does overflow incontinence and renal failure occur in chronic urinary retention?
Severe end of spectrum, when bladder capacity is reached and bladder pressure is in excess of 25cm water
(i.e. decompensated chronic urinary retention or acute-on-chronic urinary retention or high pressure chronic urinary retention)
When should you treat in chronic urinary retention?
Asymptomatic patiens with low residuals so not necessarily need treatment
Patients with symptoms or complications need treatment (but no role for medical therapy!)
What is the immediate treatment in chronic urinary retention?
Catheterisation (either urethral or suprepubic initially, followed by CISC if appropriate)
What is CISC?
Clean Intermittant Self Catheterisation
What are the complications of catheterisation in chronic urinary retention?
UTI
Post decompression haematuria
Pathological diuresis
Electrolyte abnormalities (hyponatraemia, hyperkalaemia, metabolic acidosis),
Persistant renal dysfunction due to acute tubular necrosis
What are the features of pathological diuresis?
Urine output >200ml/hr \+ Postural Hypertension (systolic differential >20mmHg between lying and standing) \+ Weight loss \+ Electrolyte abnormalities
How do you manage someone after immediate treatment in chronic urinary retention?
Manage with IV fluids (total input = 90% of output) and monitor closely; liase with renal team
- This is to prevent post-obstructive diuresis
Subsequent treatment is with either long term urethral or suprapubic catheter, CISC or TURP
What is Post obstructive diuresis (pathological diuresis)?
Postobstructive diuresis is a polyuric response initiated by the kidneys after the relief of a substantial bladder outlet obstruction. In severe cases this condition can become pathologic, resulting in dehydration, electrolyte imbalances, and death if not adequately treated
Chronic urinary retention is further divided into high and low pressure CUR.
What is the difference?
The presence or absence of intrinsic detrusor pressure is what differentiates them.
High-pressure CUR results from an obstruction with the presence of detrusor muscle activity, while low-pressure CUR involves detrusor failure with low intravesical pressure.
This distinction is important, as high detrusor pressure can lead to upper urinary tract damage and present with new-onset hypertension, peripheral edema, or renal dysfunction.
How does TURP success in chronic urinary retention compare to acute urinary retention?
Less successful outcome in chronic than fro acute retention; however, patients with high pressure chronic retention have better outcome with TURP than with low pressure chronic retention.
What are the two types of urinary tract obstruction?
Upper tract
- i.e. supra-vesical
Lower tract
- i.e. bladder outflow obstruction
Where can upper urinary tract obstruction occur?
Pelvi-Ureteric Junction
Ureter
Vesico-Ureteric Junction
Where can lower urinary tract obstruction occur?
Bladder neck Prostate Urethra Urethral meatus Foreskin (e.g. phimosis)
