Urinary Tract Stones

Question 1

What are they?

Answer 1

Solid particles that form in the urinary tract

Question 2

Why do they happen?

Answer 2

They form when the urine is supersaturated with salts and minerals e.g dehydrated

Question 3

What types are there?

Answer 3

1. Calcium Oxalate (75%)
2. Magnesium Ammonium Struvite (15%)
3. Urate (5%)
4. Hydroxyappatite (5%)
5. Brushite/Cysteine (1%)

Question 4

How big are they?

Answer 4

They vary in size from small to staghorn calculi that form in the renal pelvis

Question 5

Where do these stones form?

Answer 5

They form in the collecting ducts but can deposit anywhere along the urinary tract

Question 6

Where do they typically deposit? (3)

Answer 6

1. Pelvi-ureteric junction
2. Pelvic Brim
3. Vesicoureteric Junction

Question 7

Are they common?

Answer 7

Very common, lifetime incidence is 15%

Question 8

Who do they affect?

Answer 8

Peak age of occurrence is 20-40 years old, normally affect men 3:1

Question 9

Risk factors (11)

Answer 9

Anatomical anomalies, family history, hypertension, gout, hyperparathyroidism (calcium), immobilisation, dehydration, citrate deficiency, diuretics, higher socio-economic group, contamination e.g Melamine contaminated infant milk

Question 10

Signs and Symptoms (18)

Answer 10

*Can be asymptomatic, severe pain, colicky pain, nausea, vomiting, cannot lie still, renal obstruction, appendicitis like symptoms, bladder irritability, scrotal pain, painful penile tip or labia majora, pelvic pain, dysuria, interupted flow, no tenderness on palpation, if infected shows pyuria, haematuria and proteinuria

Question 11

Differentials (5)

Answer 11

Biliary colic, aortic dissection, pyelonephritis, acute pancreatitis, acute appendicitis

Question 12

What bloods would you do? (8)

Answer 12

FBC, U&E, CRP, Calcium, Phosphate, Glucose, Bicarb, Urate

Question 13

Other investigations (4)

Answer 13

Urinalysis, MSU MC&S, CT, abdominal/pelvic xray

Question 14

What is the treatment? (9)

Answer 14

Analgesia, fluids, antibiotics if infected, Stones <5mm generally pass spontaneously, >5mm need medical intervention e.g Nifedipine or Alpha Blockers to relax the urinary tract, Extracorporeal Shockwave Lithotripsy, Percutaneous Nephrolithostomy, Ureteric stent

Question 15

Complications (5)

Answer 15

Complete blockage of urinary flow, reduced eGFR, sepsis, ureteric stricture, pyelonephritis

Question 16

Is there a good prognosis?

Answer 16

Recurrent, 80% of stones pass spontaneously