9.2 Urinary Tract Disruption Flashcards by Samantha Bromley

Where do urinary tract obstructions occur?

At any level between the kidney to the urethra

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During bilateral urinary obstruction where is the obstruction likely to be?

At the bladder or at the urethra as ureters have converged

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What are urinary tract obstructions a risk factor for?

UTI - stagnant pools of urine
Urine reflux - up ureter
Stone formation

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What are common causes of urinary tract obstruction?

Tumours (kidney, cervix, bladder)
Strictures at pelvis ureteric junction
Stag horn calculus / ureteric calculus 
Pregnancy - obstruction of ureter 
Blood clot
Endometriosis
Damage to nerves involved in micturition
Prostatic enlargement 
Urethral stricture

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What are calculi?

Renal stones

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What are causes of urinary retention?

Calculi
Pregnancy 
Benign prostatic hypertrophy - occlusion of prostatic urethra
Recent surgery
Drugs
Urethral strictures
Pelviureteric junction obstruction - congenital abnormality 
Pelvic masses
Constipation
Inflammation of lower urinary tract/UTI
Tumours
Neurogenic disorders

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How is urinary retention imaged on a CT?

Enlarged bladder

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How does pregnancy cause urinary retention?

progesterone relaxes muscle fibres in the renal pelvis and ureters causing dysfunctional obstruction. Pressure of growing foetus can cause occlusion

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What drugs can cause urinary retention?

opioids, anticholinergics - decrease contraction of detrusor

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What neurogenic disorders can cause urinary retention?

• Congenital anomalies affecting the spinal cord
• External pressure on the cord or lumber nerve
roots
• Trauma to the spinal cord

Affect micturition pathways

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What is acute urinary retention?

Sudden inability to void
Painful
Residual volume of 300-1500ml
Can see enlarged / distended bladder

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What is chronic urinary retention?

Long term urinary retention
Painless
May still be voiding but have large residual volume (300-4000ml)

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What can cause acute urinary retention?

Flare up of begging prostatic hypertrophy
Urethral stricture
Tumours

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What can cause chronic urine retention?

Gradual occlusion

Neurological disorders.

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What is acute on chronic urinary retention?

Chronic retention, with a sudden acute urinary retention episode. Can be caused by the chronic urinary retention (e.g. stones formed due to pooling of urine) or not related.

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What is the treatment of acute urinary retention?

Catheterise and record residual urinary volume
History (urine stream, urine volume, frequency, continence, vesicle tenesmus)
Examination (abdomen, external genitalia, digital rectal examination)
Urine dip (UTI)
U&E
Treat any obvious cause (constipation)
BPH - alpha blocker, TWOC after 1-2 weeks

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What can acute urinary retention result in if not treated?

Hydronephrosis -> renal damage -> renal failure

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How would we manage chronic urinary retention?

Catheterise and record residual volume
History of urinary complications and symptoms
Examination (often have vesicle tenesmus, poor uric stream or flow)
Urine dips
U&E
Determine if High pressure urinary retention or low pressure urinary retention
Plan for long-term catheterisation or intermittent self catheterisation. Would not attempt TWOC

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How does high pressure chronic urinary retention present?

High pressure build up of urine in the bladder.
Hydronephrosis as urine back up ureters and kidney. Can develop to have deranged U&Es and AKI (post renal cause). Unable to clear K+ from body, hyperkalaemia. Over time can cause permanent renal scarring and CKD

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How does low pressure urinary retention present?

Bladder compliant but not emptying. Normal renal function, no hydronephrosis.
Likely to be due to neurological damage.
Long term catheterisation (suprapubic catheter/ intermittent self catheterisation)

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Why must urine output be monitored for 24hours post catheterisation for treating urinary obstruction?

As can develop post-obstructive diuresis following hydronephrosis as suddenly excreting build up of waste products. Do not want patient to become hypovolaemic.
Can lead to worsening AKI

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What is post- obstructive diuresis?

Over-diuresis by the kidneys following catheterisation to treat obstructive urinary retention. Occurs to clear the waste solutes in the blood the kidneys couldn’t previously expel. Can lead to worsening AKI.

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How do we support patients with post-obstructive diuresis?

IV fluid

What is hydronephrosis?

Dilation of the renal pelvis and calyces due to obstruction at any point in the urinary tract
causing increased pressure and blockage.

What causes a unilateral hydronephrosis?

Upper urinary tract obstruction (ureter or kidney)

What causes a bilateral hydronephrosis?

Lower urinary tract obstruction (BPH in males)

How does hydronephrosis appear on a CT scan?

Dilated renal pelvis

How is the kidney affected in long term hydronephrosis?

Progressive atrophy of the kidney. Transmitted through the nephron. GFR declines If bilateral the patient can go into renal failure

What occurs if there is an obstruction at the pelviureteric junction?

Hydronephrosis

What occurs if there is an obstruction at the ureter?

hydroureter, eventually developing hydronephrosis

What occurs if there is obstruction at the bladder neck/urethra?

bladder distension with hypertrophy of bladder wall and diverticula, eventually leading to bilateral hydroureter and thus hydronephrosis

What is acute ureteric obstruction?

Obstruction within the ureter. Patients present with renal colic, clammy, sweaty, nausea, vomiting. Usually unilateral, if bilateral can lead to renal failure. Bilateral patients have anuria/oliguria

What is renal colic?

Sharp pain from the lower back (loin) that radiates to the groin

What causes acute ureteric obstruction?

Often caused by a renal calculus getting stuck in the ureter, pain as ureter contracts to try and push calculus through Can also be caused by blood clots or a slough papilla.

What are slough papilla?

A slough papilla occurs due to renal papilla necrosis often caused by ischaemia, resulting in the papilla sloughing into the lumen

What can develop as a complication of acute ureteric obstruction?

Pronephrosis - infection of the kidneys collecting system. Pus collects in the renal pelvis causing distension of the kidney

What is pronephrosis?

Urological emergency. An infected, obstructed kidney. Failure to decompress promptly can lead to death from sepsis and permanent loss of renal function

How do we diagnose a urinary tract obstruction?

``` CT scan or ultrasound - would show hydronephrosis, stones appear brightly on CT Diuretic renography (MAG3) ```

What is a diuretic renography?

A functional test that tells us what’s happening in the kidney. Patients given radiotracer and we monitor radioactivity of the urine. Patients also given frusamide after

How do we drain the upper urinary tract?

Nephrostomy | JJ stent

What is a urolithiasis?

A urinary calculi

Who does urolithiasis most commonly affect?

Men Caucasians Dehydrated

Where are the most common sites for urolithiasis?

- Pelviureteric junction - pelvic brim - vesicoureteric junction But can form anywhere in the urinary tract

How do we diagnose urolithiasis?

CT scan of kidneys, ureters and bladder as show up very clearly due to high calcium content

What are the 5 types of calculi?

1. Calcium oxalate stones 2. Mixed calcium phosphate and calcium oxalate stones 3. Magnesium ammonium phosphate stones 4. Uric acid stones 5. Cystine stones

What is the most common calculi?

Calcium oxalate stones

What are calcium oxalate stones associated with?

Hypercalcaemia Primary Hyperparathyroidism Hyperoxaluria

What are mixed calcium phosphate and calcium oxalate stones associated with?

Alkaline urine

Why does the presentation of urolithiasis vary?

As site of stone can present differently. Can be asymptomatic

How does a renal stone present?

Continuous dull ache in loins

How do ureteric stones present?

renal colic due to the increase in peristalsis in the ureters in response to the passage of a small stone. Typically radiates from loin to groin. Patient appears sweaty, pale and restless with nausea and vomiting

How do bladder stones present?

Strangury (the urge to pass something that will not pass)

What symptoms can indicate urolithiasis?

Recurrent untreatable UTIs Hematuria Renal failure

Which calculi do not appear on an X-ray?

Uric acid stones

What is the general management for urolithiasis?

Adequate analgesia High fluid intake Urine sieved for analysis - then correct any underlying metabolic abnormality

What size stones can pass easily in urine?

<5mm

What surgical interventions can be used to treat urolithiasis?

* Extracorporeal shock wave lithotripsy (ESWL): shock waves are used to fragment the calculi into small pieces which will then pass out in the urine * Ureteroscopic destruction or removal of stones * Percutaneous nephrolithotomy (PCNL) : endoscopic removal of the stone * Open surgical removal