Renal Tract Calculi Flashcards
In which gender are renal tract calculi more common in
Males under 65
What are renal stones
Stones within the kidney
What are ureteric stones
Stones within the ureters
What is the most common substance that a stone in the renal tract is made up of
Calcium either as:
Calcium oxalate - 35%
Calcium phosphate - 10%
Mixed - 35%
Apart from calcium stones what are the other types of stones you can get in the renal tract
Struvite stones - magnesium ammonium phosphate
Urate stones - radiolucent
Cystine stones
What is the most common type of stone that is a stag horn
Struvite stones
What is the pathophysiology basis of urinary tract stones
Over-saturation of urine from the specific molecule in the stone eg - calcium, urate, cystine
How are urate stones formed
High level of purine in the blood through:
- diet
- haematological disorders
The above will result in high levels of urate formation and therefore subsequent oversaturation and crystallisation in the urine
How are cystine stones formed
Associated with hypocystinuria - inherited disorder that affects absorption and transport of cystine.
as citrate is a stone inhibitor, hypocitraturia from the condition can thus predispose affected individuals to recurrent stone formation.
What are the 3 points of narrowing in the ureters where stones are likely to lodge
Pelviureteric Junction (PUJ), where the renal pelvis becomes the ureter
Crossing the pelvic brim, where the iliac vessels travel across the ureter in the pelvis
Vesicoureteric Junction (VUJ), where the ureter enters the bladder
How do patients present with ureteric stones
Ureteric colic pain due to increased vermiculations around the obstruction
Sudden onset pain radiating from loin to groin
Haematuria
Flank tenderness
What are the differential diagnosis of renal tract stones
Pyelonephritis Ruptured AAA Biliary pathology Lower lobe pneumonia MSK pain
What are the lab investigations that need to be carried out
Urine dip
Routine bloods - FBC, CRP, U&Es, Urate and Calcium levels
Which imaging modalities are used to investigate Renal tract calculi
Non constrast CT KUB - gold standard
Plain film AXR
US scans - used to assess for hydronephrosis
What is the initial management of renal stones
Ensure adequate fluid resus
Analgesia
Most stones will pass spontaneously
What is the criteria for inpatient admission for pts with renal stones
Post-obstructive acute kidney injury
Uncontrollable pain from simple analgesics
Evidence of an infected stone(s)
Large stones (>5mm)
Which patients may need a stent or nephrostomy
Pts with obstructive nephropathy or significant infection to avoid renal damage
What is a retrograde stent insertion
placement of a stent within the ureter, approaching from distal to proximal via cystoscopy
What is a nephrostomy
tube placed directly into the renal pelvis and collecting system, relieving the obstruction proximally
What are the definitive management options
Extracorporeal shock wave lithotripsy ( ESWL )
Percutaneous nephrolithotomy - PCNL
Flexible uretero-renoscopy - URS
What does ESWL involve
targeted sonic waves break up the stone and the fragments are then spontaneously passed
This is reserved for smaller stones - <2cm
Performed via radiological guidance, either X-ray or US
What are the contraindications for ESWL
Pregnancy
Stone over a bony landmark
What is PCNL
For renal stones only,can be used for staghorn calculi
Percutaneous access to the kidney is performed, with a nephroscope passed into the renal pelvis. The stones can then be fragmented using various forms of lithotripsy.
What is involved in URS
involves passing a scope retrograde up into the ureter, allowing stones to be fragmented through laser lithotripsy and the fragments subsequently removed.
What are the complications of renal tract stones
Infection
Post renal AKI
Scarring of kidney - resulting in loss of kidney function
How do you manage a pt with recurrent stone formation of oxalate
avoid high purine foods and high oxalate foods (such as nuts, rhubarb, and sesame)
How do you manage a pt with recurrent stone formation of calcium
have PTH levels checked to exclude any primary hyperparathyroidism and avoid excess salt in their diet
How do you manage a pt with recurrent stone formation of urate
avoid high purine foods (such as red meat and shellfish) and may need to be considered for urate-lowering medication (e.g. allopurinol)
How do you manage a pt with recurrent stone formation of cystine
Genetic testing for underlying genetic disorder
When are bladder stones most commonly seen
Cases of chronic urinary retention leading to urine stasis
Also secondary to infections - schistosomiasis
How will bladder stones present
LUTS
How do you manage bladder stones
Same as renal and ureteric stones
what is the definitive management of stones
cystoscopy, allowing the stones to drain or fragmenting them through lithotripsy if required.
What can bladder stones pre-dispose to
development of TCC bladder cancer due to Chronic irritation of bladder epithelium
