Renal Tract Calculi

Question 1

Epidemiology

Answer 1

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.

Question 2

Types of calculi

Answer 2

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

Question 3

Which stone is most common cause of staghorn calculi

Answer 3

Struvite stones

Question 4

Pathophysiology of urate stones

Answer 4

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.

Question 5

Pathophysiology of cystine stones.

Answer 5

Associated with homocystinuria

Question 6

Location of ureteric stones.

Answer 6

Pelviureteric junction PUJ

Cross the pevlic brime where the iliac vessel travel across the ureter in the pelvis

Vesicoureteric junction VUJ

Question 7

Pathophysilogy of struvite stones

Answer 7

Due to infection in urinary tract

Proteus, Xanthomonas, Pseudomonas, Klebsiella, Staphylococcus, and Mycoplasma.

Question 8

Clinical features

Answer 8

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.

Question 9

Examination findings

Answer 9

Typically unremarkable

There might be tenderness in the affected flank

Dehydration

Question 10

Dx

Answer 10

Pyelonephritis

Ruptured AAA

Biliary pathology

Bowel obstruction

Lower lobe pneumonia

MSK pain

Question 11

Lab tests

Answer 11

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.

Question 12

Imaging

Answer 12

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.

Question 13

Initial management

Answer 13

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

Question 14

Why is tamsulosin not used anymore?

Answer 14

Limited benefit in ureteric stones and is no longer routinely prescribed.

Question 15

Criteria for inpatient admission

Answer 15

Post-obstructive AKI

Uncontrollable pain from simple analgesic

Evidence of an infected stone

Large stones >5mm

Question 16

Give immediate managements that are not definitive.

Answer 16

Stent insertion

Nephrostomy

Question 17

Why would stent insertion or nephrostomy be done if they are not definitive managements?

Answer 17

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

Question 18

Explain retrograde stent insertion.

Answer 18

Placement of a stent within the ureter

This is by cytoscopy.

It allows the ureter to be kept patent and temporarily relieve the obstruction.

Question 19

Explain nephrostomy

Answer 19

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.

Question 20

Defintiive managements

Answer 20

Extracorporeal Shock Wave Lithotripsy

Percutaneous Nephrolithotomy

Flexible uretero-renoscopy

Question 21

Explain ESWL

Answer 21

Targeted sonic waves breaks up the stone so it can then be passed spontaneously.

Question 22

Indications for ESWL

Answer 22

Small stones <2cm and where they can be located

Performed via radiological guidance like X-ray or USS

Question 23

Contraindications of ESWL

Answer 23

Pregnancy

Stone positioned over a bony landmark like pelvis

Question 24

When is PCNL used?

Answer 24

In renal stones only

It is the preferred method for large renal stones like staghorn calculi.

Question 25

Explain PCNL

Answer 25

Nephroscope passed into renal pelvis where then stones can then be fragmented.

This can cause pneumothorax or nerve damage

Question 26

Explain flexible uretero-renoscopy URS

Answer 26

A scope is retrogradely put into the ureter

This allows the stones to be fragmented through laser lithotripsy and then the fragments are removed.

Question 27

Complications of ureteric stones.

Answer 27

Infection

Post-renal AKI

Recurrency and scarring + CKD

Question 28

Management of recurrent stone formers.

Answer 28

Identify what types of stones is the problem.

Advise them to stay hydrated

Have their serum urate and calcium levels checked.

Question 29

Oxalate stone formers management

Answer 29

Avoid high purine foods and high oxalate foods like nuts, rhubarb and sesame

Question 30

Calcium stone formers management

Answer 30

PTH levels checked to exlclude primary hyperparathyroidism

Avoid excess salt in diet

Question 31

Urate stone formers management

Answer 31

Avoid high purine foods like red meat and shellfish

Allopurinolol might be considered

Question 32

Management of cystine stone formers

Answer 32

Genetic testing for familial disease

Question 33

What causes bladder stones

Answer 33

From urine stasis within the bladder

More commonly seen in chronic urinary retention.

Can also be due to infeciton classically schistosomiasis.

Question 34

Clinical features of bladder stones

Answer 34

Lower urinary tract symptoms

They require same investigations as renal and ureteric stones.

Question 35

Management of bladders stones

Answer 35

Cystoscopy allowing the stones to drain or fragment from lithotripsy

Question 36

Complication of bladder stones

Answer 36

Can cause SCC bladder cancer due to the chronic irritiation of bladder epithelium.