Urolithiasis

Question 1

Where can stones form in the urinary tract?

Answer 1

The kidney (renal stones);
The bladder (around 5% of all urolithiases)

Question 2

What are the three main causes of bladder stones?

Answer 2

Foreign bodies (e.g. catheters, sutures, meshes, synthetic tapes)
Outflow obstruction
Infection

Question 3

Medical conditions which predispose for stone formation? (4)

Answer 3

Anatomical anomalies in the kidney;
Gout;

Hyperparathyroidism;
Hypertension

Question 4

What is the classical presentation of kidney stones?

Answer 4

Renal colic

Question 5

What are the symptoms of renal colic? (8)

Answer 5

Severe, sudden onset loin --> groin pain;
Pain constant but often periods of relief;
Rigors;
Fever;
Dysuria;
Haematuria;
Urinary retention;
N&V

Question 6

How does a patient with peritonism differ in presentation from a person with renal colic?

Answer 6

Peritonism patient lies still; renal colic patient writhes around

Question 7

What does pyrexia with renal colicky-sounding pain suggest?

Answer 7

Pyelonephritis (either complicating the renal colic, or as a separate Dx)

Question 8

Differential diagnoses of the pain in renal colic?

Answer 8

Biliary colic
Aortic aneurysm dissection
Pyelonephritis
Acute pancreatitis
Acute appendicitis
Perforated peptic ulcer
Orchitis or testicular torsion
Malignant causes of back pain

Question 9

What is the imaging modality of choice?

Answer 9

Non-enhanced CT scan (replaced intravenous pyelogram)

Question 10

Why are KUB (kidney, ureter, bladder) X-rays useful?

Answer 10

Most (75%) stones are radio-opaque due to calcium; can observe passage of stones

Question 11

Management of acute presentation?

Answer 11

NSAIDs (diclofenac IM or PR) first-line; opioids if necessary
Anti-emetics and fluids if required

Question 12

What is the usual outcome of kidney stones?

Answer 12

Majority pass spontaneously but may take 1-3 weeks

Question 13

What is the composition of most urinary stones?

Answer 13

85% are calcium oxolate

Question 14

Investigations in urolithiasis? (5)

Answer 14

Dipstick- haematuria, looking for infection

MSSU for M+C+S

Blood for FBC, CRP, renal function, electrolytes, calcium, phosphate, urea

Imaging (CT)

Stone analysis if the stone can be caught

Question 15

Medical expulsive therapy for stones?

Answer 15

Calcium channel blockers e.g. nifedipine

Alpha blockers (e.g. tamsulosin) (+/- prednisolone)

Question 16

What is a JJ stent?

Answer 16

Hollow tube with two coiled ends, one placed in renal pelvis and the other in the bladder

Question 17

What is a JJ stent used for?

Answer 17

To temporarily bypass blocked/potentially blocked ureter; also helps reduce pain by preventing ureter from contracting

Question 18

Non-medical management for stones?

Answer 18

Extracorporeal shock wave lithotripsy (ESWL)

Percutaneous nephrolithotomy (PCNL)

Ureteroscopy using a laser

Open surgery- rarely necessary

Question 19

Complications of stones?

Answer 19

Blockage of urinary flow leading to decreased GFR and irreversible renal damage
Infection and sepsis
Ureteric stricture

Question 20

Stones less than what diameter are likely to pass spontaneously?

Answer 20

5mm

Question 21

Stones bigger than what size usually require intervention?

Answer 21

1cm

Question 22

What lifestyle interventions can be recommended to prevent recurrence? (4)

Answer 22

Increase fluid intake to maintain output 2-3l/day
Reduce salt intake
Reduce meat consumption
Drink regular cranberry juice

Question 23

Obstructed, infected kidney- management?

Answer 23

Percutaneous nephrostomy to relieve the pressure + IV antibiotics

Question 24

Management of a large proximal stone such as a staghorn calculus?

Answer 24

Percutaneous nephrolithotomy

Question 25

What causes the development of stag-horn calculi?

Answer 25

Develop in alkaline urine; composed of struvite; potentiated by bacteria such as Proteus which hydrolyse urea to ammonium