Stones/ Urolithiasis

Question 1

How common are urinary tract calculi? How does the size of the stone change it’s treatment?

Answer 1

Incidence of acute rena, colic (pain from renal stones) 1-2 cases/ 1000/ year

High recurrence rate 60-80%

Most small stones pass spontaneously within 1-2 months,
stones >6mm likely to require intervention

Question 2

causes of urinary calculi

Answer 2

Metabolic - secondary hypercalcuria,

UTIs: proteus, pseudomonas, klebsiella
-> scruvite stones (mineral produced by bacteria)

Diet - high table salt, obesity

Medication- furosemide

Genetic - primary hyperoxaluria, cystinuria

Question 3

How would you diagnose a urinary calculi?

Answer 3

Symptoms loin to groin pain/ haematuria -> CT KUB (kidney, ureters, bladder) diagnostic accuracy greater then 95% -> identify stone size and position/ associated obstruction/ complication and alternative diagnosis e.g. AAA, appendicitis

Question 4

How would you diagnose a large renal calculus?

Answer 4

Ultrasound - bright stone with posterior acoustic shadowing

Or KUB radiograph (bright white)

Or dual energy CT

Or DMSA split function - radiolabelled substance injected into patient and gamma camera used

Or dye injected

Question 5

How would you diagnose the composition of a stone and how would this change treatment?

Answer 5

Dual energy Ct shows composition

• urate stones treated first line with alkalisation
• high density stones e.g. brushite are fairly resistant to ESWL

Could be: calcium oxalate (75% renal stones) , calcium phosphate, Uric acid, struvite

Question 6

Treatment options for urinary calculi

Answer 6

Depends on size, location, composition

✅Extracorporeal shock- wave lithotripsy - ESWL - garments calculi, localised with fluoroscopy/ US, fragments pass out over several weeks if <2cm. (Not if in lower pole calyx, radiolucent, resistant)

✅percutaneous nephrolithotomy - PCNL (small hole into kidney)
✅ ureteroscopy

✅open surgery/ nephrectomy - avoid base of lung, go above 12th rib

Question 7

what is paediatric cystinuria? Treatment, symptoms

Answer 7

High levels of cysteine in urine -> cystine stones

✅percutaneous nephrolithotomy (drill hole through calex)

Staghorn calculus

FH
Lethargy
Recurrent UTIs

Question 8

How can you categorise Urinary stones?

Answer 8

Staghorn (filling numerous major and minor calices)
or non-staghorn - calyceal or pelvic

Ureteral stones proximal, middle or distal

Composition: 
80% calcium oxalate/ calcium phosphate 
Uric acid 9%
Struvite 10%
Cystine, drug stones, ammonium acid urate 1%