Renal Stones + Pyelonephritis

Question 1

What is the other name for renal tract stones?

Answer 1

Urolithiasis

Question 2

What are the different types of renal tract stones?

Answer 2

Calcium (80%):
- calcium oxalate
- calcium phosphate
- mixed
Struvite (magnesium ammonium phosphate)
Urate
Cystine

Question 3

What type of stones classically cause ‘stag horn calculi’?

Answer 3

Struvite

Question 4

Which stones are radiolucent (can’t be seen on xray)?

Answer 4

Urate stones

Question 5

What causes the development of urate stones?

Answer 5

High levels of purine in the blood

• e.g. from diet (red meats)
• or haematological disorders e.g. myeloproliferative disease

Question 6

What causes the development of cystine stones?

Answer 6

Familial disorders affecting cystine metabolism - hypocystinuria

Question 7

What are the three main locations when renal tract stones are found?

Answer 7

Natural narrowed points:

• pelviureteric junction (PUJ)
• where iliac vessels cross the ureter in the pelvis
• vesicoureteric junction (VUJ)

Question 8

What are the clinical features of a renal tract stone?

Answer 8

Asymptomatic if non obstructing
Ureteric stone:
- pain --> ureteric colic
- sudden onset, 'loin to groin'
- associated nausea + vomiting
- haematuria in 90%
- fever, rigors if associated infection

Question 9

How should suspected urolithiasis be investigated?

Answer 9

Urinalysis +/- culture
Bloods:
- FBC + CRP
- U&Es
- urate + calcium levels
Imaging

Question 10

Which imaging is gold standard for urolithiasis?

Answer 10

Non-contrast CT KUB

USS is useful to look for hydronephrosis in cases of known stone disease

Question 11

What is the initial management of urolithiasis?

Answer 11

Often dehydrated so ensure adequate fluid intake
ANALGESIA - opiates + rectal NSAIDs (diclofenac)
Majority of stones pass spontaneously, especially if in lower ureter or < 5mm

If signs of infection –> IV antibiotics + urgent urology referral

Question 12

What is the criteria for inpatient admission for urolithiasis?

Answer 12

Post obstructive AKI
Uncontrolled pain from simple analgesia
Evidence of infection
Large stones (>5mm)

Question 13

Which methods are used to temporarily relieve obstruction in urolithiasis if there is nephropathy or infection?

Answer 13

Stent insertion:
- into ureter via cystoscopy
or Nephrostomy:
- tube directly into renal pelvis to relieve the obstruction proximally

Question 14

What are the options for definitive management of renal/ureteric stones which do not pass spontaneously?

Answer 14

Extracorporeal shock wave lithotripsy (ESWL)
Percutaneous nephrolithotomy (PCNL)
Flexible uretero-renoscopy (URS)

Question 15

What is extracorporeal shock wave lithotripsy (ESWL) and when is it used/contraindicated?

Answer 15

Targeted sonic waves to break up stone
Used for small stones (<2cm)
CI: pregnancy or stone positioned over bony landmark e.g. pelvis

Question 16

What is percutaneous nephrolithotomy (PCNL) and when is it used?

Answer 16

Used of renal stones only –> best method for large renal stones including staghorn calculi

Percutaneous access to kidney, nephroscope passed into renal pelvis + stones fragmented using lithotripsy

Question 17

What is flexible uretero-renoscopy (URS)?

Answer 17

Scope passed retrograde up into ureter + stones fragmented through laser lithotripsy

Question 18

What are the main complications of urolithiasis?

Answer 18

Infection
Post-renal AKI
Recurrent renal stones –> renal scarring and loss of kidney function

Question 19

What causes bladder stones?

Answer 19

Urine stasis –>chronic urinary retention
Infection –> schistosomiasis
Passed ureteric stones

Question 20

What are the clinical features of pyelonephritis?

Answer 20

Classical triad:

• fever
• unilateral loin pain
• nausea + vomiting

May be symptoms of lower UTI + haematuria
Costovertebral angle tenderness

Question 21

How should suspected pyelonephritis be investigated?

Answer 21

Urinalysis + culture
Beta-HCG
Routine bloods

If evidence of obstruction:

• renal USS (infected obstruction is urological emergency)
• then non-contrast CT KUB

Question 22

How is pyelonephritis managed?

Answer 22

If uncomplicated - antibiotics in the community

If systemically unwell -

• ABCDE
• IV fluids + empirical antibiotics
• analgesia + anti-emetics

Question 23

What are the complications of pyelonephritis?

Answer 23

Severe sepsis
Renal scarring --> CKD
Pyonephrosis (infected obstructed kidney)
Preterm labour in pregnant women
Chronic pyelonephritis --> CKD
Emphysematous pyelonephritis

Question 24

What is emphysematous pyelonephritis?

Answer 24

Rare, sever pyelonephritis caused by gas forming bacteria –> high mortality
Most commonly seen in diabetics
CT –> gas within and around the kidney