Urolithiasis

Question 1

Pathophysiology of renal stones

Answer 1

(1. ) Renal stones are mineral deposits that form microscopic crystals
(2. ) This forms when form amount of crystal forming substances (eg. calcium, oxalate, uric acid) is higher than the fluid in urine (known as supersaturation of urine).
(3. ) Once crystals have formed, they either pass out with the urine OR remain in the kidney, where they can develop into stone

Question 2

Presentation of renal stones (6).

Answer 2

(1.) Asymptomatic

(2. ) Loin (to groin) pain
- Rapid onset, sharp, severe
- N+V

(3. ) Unilateral renal colic
(4. ) UTI Sx, recurrent UTIs
(5. ) Haematuria
(6. ) Urinary retention

Question 3

Investigations of renal stones and GOLD standard Ix

Answer 3

PT IN PAIN: Perform ABC and give analgesia/antiemetic

(1. ) Urinalysis
(2. ) FBC, U&E, Ca, Uric acid

Imaging

(3. ) NCCT-KUB (GOLD): pick up majority of stones
(4. ) KUBXR
(5. ) USS
- poor for visualising stones
- can show structural abnormalities
- for pregnancy, children as no radiation risk
(6. ) Intravenous urogram: rarely used now

Question 4

Consequences of stones

Answer 4

1. Small stones (<1cm)
   - Can migrate into ureter
2. Larger stones
   - Occlude calyces and/or pelvic ureteric junction (PUJ)
3. Infective stones
   - Can cause chronic renal damage
   - Abscesses
   - Fistulae
   - XPN (pyelonephritis)
4. Pyonephrosis
   - This is a combination of kidney infection and obstruction
   - Can lose renal function in 24hrs
   - Systemic sepsis can lead to septic shock
   - Tx = IV antibiotics, Oxygen, drainage via nephrostomy or ureteric stenting

Question 5

Tx and Mx of renal stones (8)

Answer 5

(1.) No Tx if small, safe, asymptomatic

(2. ) Analgesia (NSAIDS - diclofenac or IV paracetamol)
(3. ) Antiemetics

Renal 1-2cm, Ureteric Stone

(4. ) Shockwave lithotripsy (ESWL, SWL)
(5. ) Ureteroscopy: laser, basket extraction, lithoclast

Larger stones
(6.) Percutaneous Nephrolithotomy, PCNL

If stone & renal colic within 48hrs of Dx and ongoing pain, not tolerated or unlikely to pass
(7.) Surgery and Stent placement

(8.) If Sepsis: drainage, nephrectomy or stent

Question 6

Prevention of Stones

Answer 6

• Keep hydrated
• Low salt diet
• Normal diary intake
• Moderate protein intake
• Reduce BMI (metabolic syndrome)
• Active lifestyle

Question 7

ANATOMY Q: Three sites where renal stone may pass to cause severe pain.

Answer 7

The ureter has three narrowing’s which may be too small for the stone to pass through these are:

(1. ) where the pelvis of the kidney becomes the ureter (PUJ)
(2. ) pelvic brim
(3. ) where the ureter enters bladder