Session 9: Urolithiasis

Question 1

What are urinary calculi most commonly formed from?

Answer 1

Calcium

Question 2

Aetiology of urinary tract stones.

Answer 2

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.

Question 3

Can you differentiate between different urinary tract stones purely on clinical presentation?

Answer 3

Usually not, they all share more or less similar presentation.

Question 4

How can different urinary tract stones be categorised?

Answer 4

Based on location

Question 5

How can different kidney stones be categorised?

Answer 5

As staghorn or non-staghorn.

Question 6

What are staghorn kidney stones?

Answer 6

They fill numerous major and minor calices.

Question 7

How can non-staghorn kidney stones be categorised?

Answer 7

Whether they are calyceal or pelvic in location.

Question 8

How can ureteral stones be categorised?

Answer 8

Proximal

Middle

Distal

Question 9

Commom clinical presentation of urinary calculi.

Answer 9

Loin to groin pain

Haematuria (might not be visible but show up on dipstick)

Question 10

How to diagnose urinary calculi.

Answer 10

CT scan is the golden standard with a diagnostic accuracy of more than 95%.

Question 11

What is important to identify on the CT scan concerning a urinary calculi?

Answer 11

The stone size, position as well as associated obstruction or other complication.

Question 12

Dx of urinary calculi

Answer 12

Ruptured AAa

Pancreatitis

Appendicitis

Question 13

In what other way might you diagnose renal calculi?

Answer 13

Ultrasound scan or x-ray.

This is usually done incidentally.

Question 14

What are the majority of kidney stones made of?

Answer 14

Calcium oxalate (CaOx) and calcium phosphate (CaP)

Question 15

What else can kidney stones be made of?

Answer 15

Uric acid (urate stones), struvite, cystine, drug stones, ammonium acid urate.

Uric acid (9%), struvite (10%) and cystine are most common

Question 16

What are struvite kidney stones?

Answer 16

Magnesium ammonium phosphate hexahydrate from infection by bacteria that possess the enzyme urease.

Question 17

How to treat urate stones.

Answer 17

Alkanisation

Question 18

What does the likelihood of passage of a ureteric stone largely depend on?

Answer 18

The size of the stone.

Question 19

Likelihood of need of treatment of a stone <2mm.

Answer 19

3%

Question 20

Likelihood of need of treatment of a stone 3 mm

Answer 20

14%

Question 21

Likelihood of need of treatment of a stone 4-6 mm

Answer 21

50%

There is a 50% likelihood for it to pass.

Question 22

Likelihood of need of treatment of a stone >7mm

Answer 22

99%

Very unlikely to pass

Question 23

What does treatment depend on?

Answer 23

The stone size, its location and also its composition (density)

Question 24

Give examples of treatment of urinary calculi.

Answer 24

Extracorporeal shock-wave lithotripsy (ESWL)

Percutaneous nephrolithotripsy (PCNL)

Ureteroscopy

Open surgery/nephrectomy

Question 25

Advantages of ESWL.

Answer 25

Non-invasive

Uses shock-waves and nothing with ionising radiation

Highly effective

Question 26

Disadvantages of ESWL.

Answer 26

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.

Question 27

When is ESWL suitable treatment?

Answer 27

<2 cm stone

Localised stone on imaging

Question 28

When is ESWL not suitable?

Answer 28

When the stone is large >2 cm.

In lower pole calyx

Radiolucent stone

Resistant to ESWl

Question 29

Advantages of PCNL.

Answer 29

Can remove large stones

Effective

Question 30

Disadvantages of PCNL.

Answer 30

Invasive

Painful afterwards

Risk of infection post-treatment

Risk of pneumothorax

Question 31

Why might a pneumothorax develop in a PCNL?

Answer 31

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.

Question 32

Answer 32