Renal Tract Calculi

Question 1

In which gender are renal tract calculi more common in

Answer 1

Males under 65

Question 2

What are renal stones

Answer 2

Stones within the kidney

Question 3

What are ureteric stones

Answer 3

Stones within the ureters

Question 4

What is the most common substance that a stone in the renal tract is made up of

Answer 4

Calcium either as:
Calcium oxalate - 35%
Calcium phosphate - 10%
Mixed - 35%

Question 5

Apart from calcium stones what are the other types of stones you can get in the renal tract

Answer 5

Struvite stones - magnesium ammonium phosphate

Urate stones - radiolucent

Cystine stones

Question 6

What is the most common type of stone that is a stag horn

Answer 6

Struvite stones

Question 7

What is the pathophysiology basis of urinary tract stones

Answer 7

Over-saturation of urine from the specific molecule in the stone eg - calcium, urate, cystine

Question 8

How are urate stones formed

Answer 8

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

Question 9

How are cystine stones formed

Answer 9

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.

Question 10

What are the 3 points of narrowing in the ureters where stones are likely to lodge

Answer 10

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

Question 11

How do patients present with ureteric stones

Answer 11

Ureteric colic pain due to increased vermiculations around the obstruction

Sudden onset pain radiating from loin to groin

Haematuria

Flank tenderness

Question 12

What are the differential diagnosis of renal tract stones

Answer 12

Pyelonephritis 
Ruptured AAA
Biliary pathology 
Lower lobe pneumonia 
MSK pain

Question 13

What are the lab investigations that need to be carried out

Answer 13

Urine dip

Routine bloods - FBC, CRP, U&Es, Urate and Calcium levels

Question 14

Which imaging modalities are used to investigate Renal tract calculi

Answer 14

Non constrast CT KUB - gold standard

Plain film AXR

US scans - used to assess for hydronephrosis

Question 15

What is the initial management of renal stones

Answer 15

Ensure adequate fluid resus

Analgesia

Most stones will pass spontaneously

Question 16

What is the criteria for inpatient admission for pts with renal stones

Answer 16

Post-obstructive acute kidney injury

Uncontrollable pain from simple analgesics

Evidence of an infected stone(s)

Large stones (>5mm)

Question 17

Which patients may need a stent or nephrostomy

Answer 17

Pts with obstructive nephropathy or significant infection to avoid renal damage

Question 18

What is a retrograde stent insertion

Answer 18

placement of a stent within the ureter, approaching from distal to proximal via cystoscopy

Question 19

What is a nephrostomy

Answer 19

tube placed directly into the renal pelvis and collecting system, relieving the obstruction proximally

Question 20

What are the definitive management options

Answer 20

Extracorporeal shock wave lithotripsy ( ESWL )

Percutaneous nephrolithotomy - PCNL

Flexible uretero-renoscopy - URS

Question 21

What does ESWL involve

Answer 21

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

Question 22

What are the contraindications for ESWL

Answer 22

Pregnancy

Stone over a bony landmark

Question 23

What is PCNL

Answer 23

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.

Question 24

What is involved in URS

Answer 24

involves passing a scope retrograde up into the ureter, allowing stones to be fragmented through laser lithotripsy and the fragments subsequently removed.

Question 25

What are the complications of renal tract stones

Answer 25

Infection

Post renal AKI

Scarring of kidney - resulting in loss of kidney function

Question 26

How do you manage a pt with recurrent stone formation of oxalate

Answer 26

avoid high purine foods and high oxalate foods (such as nuts, rhubarb, and sesame)

Question 27

How do you manage a pt with recurrent stone formation of calcium

Answer 27

have PTH levels checked to exclude any primary hyperparathyroidism and avoid excess salt in their diet

Question 28

How do you manage a pt with recurrent stone formation of urate

Answer 28

avoid high purine foods (such as red meat and shellfish) and may need to be considered for urate-lowering medication (e.g. allopurinol)

Question 29

How do you manage a pt with recurrent stone formation of cystine

Answer 29

Genetic testing for underlying genetic disorder

Question 30

When are bladder stones most commonly seen

Answer 30

Cases of chronic urinary retention leading to urine stasis

Also secondary to infections - schistosomiasis

Question 31

How will bladder stones present

Answer 31

LUTS

Question 32

How do you manage bladder stones

Answer 32

Same as renal and ureteric stones

Question 33

what is the definitive management of stones

Answer 33

cystoscopy, allowing the stones to drain or fragmenting them through lithotripsy if required.

Question 34

What can bladder stones pre-dispose to

Answer 34

development of TCC bladder cancer due to Chronic irritation of bladder epithelium