Renal Tract Calculi Flashcards
Epidemiology
2-3% of western population
More common in males and typically affect those <65 yrs
They can either form as renal stones or ureteric stones.
Types of calculi
Calcum oxalate (35%)
Calcium phosphate (10%)
Mixed oxalate and phosphate (35%)
Struvite stones (magnesium ammonium phosphate that are often large soft stones)
Urate stones (only radiolucent one)
Cystine stones
Which stone is most common cause of staghorn calculi
Struvite stones
Pathophysiology of urate stones
High levels of purine in the blood from either diet like red meast, haematological disorders like myeloproliferative disease.
This leads to increase of urate formation and subsequent crystallisation in the urine.
Pathophysiology of cystine stones.
Associated with homocystinuria
Location of ureteric stones.
Pelviureteric junction PUJ
Cross the pevlic brime where the iliac vessel travel across the ureter in the pelvis
Vesicoureteric junction VUJ
Pathophysilogy of struvite stones
Due to infection in urinary tract
Proteus, Xanthomonas, Pseudomonas, Klebsiella, Staphylococcus, and Mycoplasma.
Clinical features
Pain as ureteric colic
This occurs from increased peristalsis from around the site of obstruction.
Pain is sudden onset, severe and radiation from flank to pelvis i.e. loin to groin.
Often associated with N+V
Haematuria in 90% of cases which is typically non-visible.
There might be infection and rigors, fever and lethargy.
Examination findings
Typically unremarkable
There might be tenderness in the affected flank
Dehydration
Dx
Pyelonephritis
Ruptured AAA
Biliary pathology
Bowel obstruction
Lower lobe pneumonia
MSK pain
Lab tests
Urine dip can show haematuria + send of urine culture as well.
Routine bloods with FBC, CRP and U&Es.
Urate and calcium levels should be assessed.
Imaging
Gold standard is non-contrast CT-KUB scan.
AXR is sometimes used as initial but not all stones are radio-opaque
USS can be used to assess for any hydronephrosis.
Initial management
Often dehydrated due to reduced oral fluid intake and or vomiting so fluid resus is required.
Majoirty will pass it spontaneously without further intervention, especially if in lower ureter or <5 mm in diameter.
Sufficient analgesia like opiate and NSAIDs per rectum is most effective
Evidence of significant infection or sepsis warrants IV abx
Why is tamsulosin not used anymore?
Limited benefit in ureteric stones and is no longer routinely prescribed.
Criteria for inpatient admission
Post-obstructive AKI
Uncontrollable pain from simple analgesic
Evidence of an infected stone
Large stones >5mm
Give immediate managements that are not definitive.
Stent insertion
Nephrostomy
Why would stent insertion or nephrostomy be done if they are not definitive managements?
Obstructive nephropathy or significant infection may warrant it.
This is where the obstruction needs to be immediately relieved to avoid renal damage.
They provide temporary relief prior to definitive management
Explain retrograde stent insertion.
Placement of a stent within the ureter
This is by cytoscopy.
It allows the ureter to be kept patent and temporarily relieve the obstruction.
Explain nephrostomy
A tube placed directly into the renal pelvis and collecting system.
This is relieving the obstruction proximally.
An anterograde stent might be put in at the same time.
Defintiive managements
Extracorporeal Shock Wave Lithotripsy
Percutaneous Nephrolithotomy
Flexible uretero-renoscopy
Explain ESWL
Targeted sonic waves breaks up the stone so it can then be passed spontaneously.
Indications for ESWL
Small stones <2cm and where they can be located
Performed via radiological guidance like X-ray or USS
Contraindications of ESWL
Pregnancy
Stone positioned over a bony landmark like pelvis
When is PCNL used?
In renal stones only
It is the preferred method for large renal stones like staghorn calculi.
Explain PCNL
Nephroscope passed into renal pelvis where then stones can then be fragmented.
This can cause pneumothorax or nerve damage
Explain flexible uretero-renoscopy URS
A scope is retrogradely put into the ureter
This allows the stones to be fragmented through laser lithotripsy and then the fragments are removed.
Complications of ureteric stones.
Infection
Post-renal AKI
Recurrency and scarring + CKD
Management of recurrent stone formers.
Identify what types of stones is the problem.
Advise them to stay hydrated
Have their serum urate and calcium levels checked.
Oxalate stone formers management
Avoid high purine foods and high oxalate foods like nuts, rhubarb and sesame
Calcium stone formers management
PTH levels checked to exlclude primary hyperparathyroidism
Avoid excess salt in diet
Urate stone formers management
Avoid high purine foods like red meat and shellfish
Allopurinolol might be considered
Management of cystine stone formers
Genetic testing for familial disease
What causes bladder stones
From urine stasis within the bladder
More commonly seen in chronic urinary retention.
Can also be due to infeciton classically schistosomiasis.
Clinical features of bladder stones
Lower urinary tract symptoms
They require same investigations as renal and ureteric stones.
Management of bladders stones
Cystoscopy allowing the stones to drain or fragment from lithotripsy
Complication of bladder stones
Can cause SCC bladder cancer due to the chronic irritiation of bladder epithelium.
