Urolithiasis

Question 1

Pathophysiology of urolithiasis

Answer 1

• ↑ Concentration of urinary solute
• ↓ Urine volume
• Urinary stasis

Question 2

most common sites to find renal stones

Answer 2

• Pelviureteric junction
• Crossing the iliac vessels at the pelvic brim
• Under the vas or uterine artery
• Vesicoureteric junction

Question 3

renal stone types

Answer 3

1. Calcium oxalate: 75%
2. Triple phosphate (struvite): 15%
3. Urate: 5%
4. Cystine: 1%

Question 4

Calcium Oxalate stones ass with?

Answer 4

crohns

Question 5

What are struvate stones ass with?

Answer 5

proteus infection

Question 6

X ray appearance of Urate and cystine stones

Answer 6

Urate radiolucent

Cystine radiofaint

Question 7

factors associated with formation of renal stones

Answer 7

• Dehydration
• Hypercalcaemia: 1O HPT, immobilisation
• ↑ oxalate excretion
• UTIs
• Hyperuricaemia: e.g. gout
• Urinary tract abnormalities: e.g. bladder diverticulae
• Drugs

Question 8

Drugs leading to stones formation

Answer 8

furosemide

thiasides

Question 9

Food with high amounts of oxalates

Answer 9

strawberries

tea

chocolate

Question 10

General presentation of renal stones

Answer 10

• bladder or urethral obstruction
• UTI
• Haematuria
• sterile pyuria

Question 11

features of ureteric colic

Answer 11

• Severe loin pain radiating to the groin
• Assoc. with n/v
• Pt. cannot lie still

Question 12

Features of bladder or urethral obstruction

Answer 12

Storage/voiding sx

Suprapubic pain radiating → tip of penis or in labia

Pain and haematuria worse at the end of micturition

Question 13

Blood investigations for renal stones

Answer 13

Ca

PO4

Urate

Question 14

Imaging for renal stones

Answer 14

• Kidney, Ureter, Bladder (KUB) X-ray/CT
• Ultrasound
• Intravenous Urogram (IVU)

Question 15

usefulness of KUB X-ray

Answer 15

• 90% of stones radio-opaque
• Urate stones are radiolucent, cysteine stones are faint

Question 16

what does ultrasound help to identify?

Answer 16

hydronephrosis

Question 17

usefulness of CT-KUB

Answer 17

• 99% of stones visible- GOLD standard

Question 18

features of Intravenous Urogram (IVU)

Answer 18

• 600x radiation dose of KUB- IV contrast injected and control, immediate and serialfilms taken until contrast @ level of obstruction

Question 19

Abnormal findings of Intravenous Urogram

Answer 19

• Failure of flow to the bladder
• Standing column of contrast
• Clubbing of the calyces: back pressure
• Delayed, dense nephrogram: no flow from kidney

Question 20

contraindications to Intravenous Urogram

Answer 20

• Contrast allergy
• Severe asthma
• Metformin
• Pregnancy

Question 21

functional scans for renal stones

Answer 21

• DMSA: dimercaptosuccinic acid

(DTPA: diethylenetriamene penta-acetic acid

or MAG-3)

Question 22

prevention of renal stones

Answer 22

• Drink plenty
• Treat UTIs rapidly
• ↓ oxalate intake: chocolate, tea, strawberries

Question 23

Initial treatment of renal stones

Answer 23

1. Analgesia
2. Fluids
3. Abx if infection: e.g cefuroxime 1.5mg IV TDS

Question 24

Conservative management of renal stones

Answer 24

90-95% pass spontaneously

Can discharge pt. c¯ analgesia

Sieve urine to collect stone for out-patient analysis

Question 25

indications for medical expulsive therapy (MET)

Answer 25

- stone 5-10mm - stone expected to pass NOT USED ANYMORE

Question 26

drugs used in medical expulsive therapy

Answer 26

- Nifedipine or tamsulosin- ± prednisolone - Most pass w/i 48h, 80% w/i 30d

Question 27

Indications for active stone removal

Answer 27

- Low likelihood of spontaneous passage: e.g. \>10mm - Persistent obstruction - Renal insufficiency - Infection

Question 28

methods of active stone removal

Answer 28

- Extracorporeal Shockwave Lithotripsy (SWL) - Ureterorenoscopy (URS) + Dormier Basket Removal - Percutaneous Nephrolithotomy (PNL) - laparoscopic or open surgery (rare)

Question 29

Side effects of Extracorporeal Shockwave Lithotripsy (SWL)

Answer 29

renal injury may → ↑BP

Question 30

Contraindications to Extracorporeal Shockwave Lithotripsy (SWL)

Answer 30

pregnancy AAA Bleeding diathesis

Question 31

Treatment of patient who is febrile with renal obstruction

Answer 31

- Surgical emergency - Percutaneous nephrostomy or ureteric stent - IV Abx: e.g. cefuroxime 1.5g IV TDS

Question 32

Treatment for stone in renal pelvis

Answer 32

- \>20mm = PNL or URS - \<20mm = SWL

Question 33

Treatment for stone in proximal ureter

Answer 33

- \>10mm = URS or SWL - \<10mm = SWL

Question 34

Treatment for stone in distal ureter

Answer 34

- \>10mm = URS - \<10mm = URS or SWL