Renal Tract Calculi

Question 1

What is the are most common types of renal tract stones?

Answer 1

Calcium oxalate
Calcium phosphate
Mixed

Struvite (magnesium ammonium phosphate) - most common cause of staghorn calculi - related to infection.
Urate - radiolucent
Cystine (typically associated with familial disorders affecting cysteine metabolism)

Question 2

What is the pathophysiology of renal tract stones?

Answer 2

Over-saturation of urine - dehydration major cause

Can also be caused by high levels of purine in blood from either diet (e.g.red meat) or through haematological disorders (myeloprolifetative disease)

Cystine stones can be caused by homocystinuria which is an inherited disorder that affects absorption and transport of cystine in bowel and kidneys; citrate is a stone inhibitor.

Question 3

Name a stone inhibitor in the context of renal tract stones?

Answer 3

Citrate

Question 4

What are the risk factors for renal tract stones?

Answer 4

Dehydration 
<65 yrs 
High protein diet 
Obesity 
DM 
FH 
Metabolic conditions 
Males 
Bowel surgery 

Idiopathic

Question 5

What are the three common locations of renal tract stones?

Answer 5

PUJ
Crossing the pelvic brim - where iliac vessels travel across the ureter in the pelvis
VUJ

Question 6

What are the clinical features of renal tract stones?

Answer 6

Pain which is sudden onset, severe and radiating from flank to pelvis (loin to groin)
N/V
Microscopic haematuria
Infection - rigours, fevers or lethargy

Exam - tenderness in affected flank, signs of dehydration

Question 7

What are the differential diagnosis for renal tract stones?

Answer 7

Pyelonephritis 
Ruptured AAA
Biliary pathology 
Bowel obstruction 
Lower lobe pneumonia 
MSK pain

Question 8

What investigations should be requested for in renal tract stones?

Answer 8

Urine dip
Bloods : FBC, U&Es, CRP, urate and calcium levels
If passed stone then send for analysis

Imaging -
non-contrast CT scan of renal tract - CT KUB
Plain film abdo x-ray - (IVU no longer used)
Ultrasound scans

Question 9

What can be seen on urine do in renal tract stones?

Answer 9

Microscopic haematuria - 90% of time

Evidence of infection - Should send urine culture as well in this case

Question 10

What are the disadvantages of abominable x-ray in renal tract stones?

Answer 10

Not all stones are radio-opaque

Question 11

What can you assess on ultrasound scan of renal tract stones?

Answer 11

Hydronephrosis

Renal stones not ureteric stones

Question 12

What is the initial management of of renal tract stones?

Answer 12

Adequate fluid resuscitation - often dehydrated

Most cases they pass spontaneously especially if in lower ureter or <5mm in diameter - so ensure pt has sufficient analgesia in mean time

If evidence of infection or sepsis - sepsis 6, IV antibiotics and urgent referral to urology team

Question 13

What are the most effective analgesia in renal tract stones?

Answer 13

Opiate

NSAIDS per rectum

Question 14

What is the criteria for inpatient admission in renal tract stones?

Answer 14

Post-obstructive AKI (renal impairment)
Uncontrolled pain from simple analgesics
Evidence of infected stones
Large stone (>5mm)

Solitary kidney - one kidney

Question 15

What are the temporary management in obstructive nephropathy or significant infection?

Answer 15

Retrograde stent insertion - JJ stent

Nephrostomy - used if patient not fit for surgery as done under LA

Question 16

What are the definitive management options for renal tract stones?

Answer 16

Extracorporeal shock wave lithotripsy (ESWL)

Percutaneous nephrolithotomy (PCNL)

Flexible uretero-renoscopy (URS)

Question 17

When is ESWL used for renal tract stones?

Answer 17

Reserved for small stones (<2cm)

Question 18

What are the contraindications for ESWL?

Answer 18

Pregnancy
Stone positioned over Bony landmark (e.g. pelvis)
Pts on anticoagulation

Question 19

What are the radiological divisions of the ureter?

Answer 19

Proximal
Middle - at sacrum
Distal

Question 20

What are the complications of ESWL?

Answer 20

Bruising

Haemtoma - contraindicated in anticoagulation

Question 21

What are the complications of urteroscopy?

Answer 21

Ureter avulsion - rare

GA effects

General surgical complications

Question 22

What are the complications of PCNL?

Answer 22

Bleeding is a major one which can be treated with embolisation

General surgery complications

Question 23

What are the complications of renal tract calculi?

Answer 23

Infection

Post-renal AKI

Recurrent renal stones

Question 24

What should be the management/advise to patients with recurrent stones?

Answer 24

Identify underlying cause and treat as appropriate - serum calcium + urate, check PTH to exclude primary hyperparathyroidism, urate stone (allopurinol), genetic testing for cystine stones

Stay hydrated

Avoid high purine foods and high oxalate food (nuts, rhubarb, sesame)

Avoid excess salt and sugar

Question 25

What are the cause of bladder stones?

Answer 25

Urine stasis with the bladder so often seen in chronic urinary retention

Secondary to infections (classically schistosomiasis) or as passed ureteric stones

Question 26

What is the definitive management of bladders stones?

Answer 26

Cystoscopy allowing stones to drain or fragmenting them through lithotripsy

Question 27

What can bladder stones predispose to?

Answer 27

SCC bladder cancer due to the chronic irritation of the bladder epithelium