Session 9: Urolithiasis Flashcards
What are urinary calculi most commonly formed from?
Calcium
Aetiology of urinary tract stones.
Metabolic like hypercalcuria
UTIs due to proteus, pseudomonas or klebsiella
Diet - ketogenic, high red meat, high table salt content, obesity
Medication like furosemide
Genetic - primary hyperoxaluria or cystinuria.
Can you differentiate between different urinary tract stones purely on clinical presentation?
Usually not, they all share more or less similar presentation.
How can different urinary tract stones be categorised?
Based on location
How can different kidney stones be categorised?
As staghorn or non-staghorn.
What are staghorn kidney stones?
They fill numerous major and minor calices.
How can non-staghorn kidney stones be categorised?
Whether they are calyceal or pelvic in location.
How can ureteral stones be categorised?
Proximal
Middle
Distal
Commom clinical presentation of urinary calculi.
Loin to groin pain
Haematuria (might not be visible but show up on dipstick)
How to diagnose urinary calculi.
CT scan is the golden standard with a diagnostic accuracy of more than 95%.
What is important to identify on the CT scan concerning a urinary calculi?
The stone size, position as well as associated obstruction or other complication.
Dx of urinary calculi
Ruptured AAa
Pancreatitis
Appendicitis
In what other way might you diagnose renal calculi?
Ultrasound scan or x-ray.
This is usually done incidentally.
What are the majority of kidney stones made of?
Calcium oxalate (CaOx) and calcium phosphate (CaP)
What else can kidney stones be made of?
Uric acid (urate stones), struvite, cystine, drug stones, ammonium acid urate.
Uric acid (9%), struvite (10%) and cystine are most common
What are struvite kidney stones?
Magnesium ammonium phosphate hexahydrate from infection by bacteria that possess the enzyme urease.
How to treat urate stones.
Alkanisation
What does the likelihood of passage of a ureteric stone largely depend on?
The size of the stone.
Likelihood of need of treatment of a stone <2mm.
3%
Likelihood of need of treatment of a stone 3 mm
14%
Likelihood of need of treatment of a stone 4-6 mm
50%
There is a 50% likelihood for it to pass.
Likelihood of need of treatment of a stone >7mm
99%
Very unlikely to pass
What does treatment depend on?
The stone size, its location and also its composition (density)
Give examples of treatment of urinary calculi.
Extracorporeal shock-wave lithotripsy (ESWL)
Percutaneous nephrolithotripsy (PCNL)
Ureteroscopy
Open surgery/nephrectomy
Advantages of ESWL.
Non-invasive
Uses shock-waves and nothing with ionising radiation
Highly effective
Disadvantages of ESWL.
Need to localise the stone and see it before being able to use it. (This is done via fluorscopy or ultrasound).
It fragments the calculi and small fragments will pass out over several weeks which can be painful.
When is ESWL suitable treatment?
<2 cm stone
Localised stone on imaging
When is ESWL not suitable?
When the stone is large >2 cm.
In lower pole calyx
Radiolucent stone
Resistant to ESWl
Advantages of PCNL.
Can remove large stones
Effective
Disadvantages of PCNL.
Invasive
Painful afterwards
Risk of infection post-treatment
Risk of pneumothorax
Why might a pneumothorax develop in a PCNL?
Because the tube is going in around T11.
The base of the lung can extend to around T12 meaning it is possible to puncture the lung and cause a pneumothorax.
