Urology

Question 1

Calcium stones

Answer 1

• Seventy-five per cent of all urinary calculi.

* Usually combined with oxalate or phosphate, are sharp, and may cause symptoms, even when small.

Question 2

Triple phosphate stones (‘struvite stones’)

Answer 2

• Compounds of magnesium, ammonium, and calcium phosphate.
• Fifteen per cent of all calculi.
• Commonly occur against a background of chronic urinary infection and may grow rapidly.
• ‘Staghorn’ calculi (fill the calyceal system) are a form of struvite.

Question 3

Uric acid stones

Answer 3

• As a consequence of high levels of uric acid in the urine.

* Five per cent of all urinary stones; radiolucent.

Question 4

Cystine stones

.

Answer 4

• Relatively rare; 1–2% of all cases.

* Difficult to treat due to extremely hard consistency

Question 5

Clinical features of renal tract stones

Answer 5

• ‘Ureteric/renal colic’. Severe, intermittent, stabbing pain radiating from loin to groin.
• Microscopic or, rarely, frank haematuria.
• Systemic symptoms such as nausea, vomiting, tachycardia, pyrexia.
• Loin or renal angle tenderness due to infection or inflammation.
• Iliac fossa tenderness if the calculus has passed into the distal ureter.

Question 6

Acute treatment of renal stones

Answer 6

• Analgesia, e.g. diclofenac 100mg PR; antiemetic, e.g. metoclopramide 10mg IV; IV fluids.
• Small stones (<0.5cm) may be managed expectantly as most will pass spontaneously.
• Emergency treatment with percutaneous nephrostomy and/or ureteric stent insertion is necessary if either pain or obstruction is persistent.

Question 7

Prevention of recurrence of renal stones

Answer 7

• Increase oral fluid intake and reduce calcium intake.
• Correct metabolic abnormalities.
• Treat infection promptly.
• Urinary alkalization, e.g. sodium bicarbonate 5–10g/24h PO in water (mainly for cystine and urate stones).
• Thiazide diuretics (for idiopathic hypercalciuria).

Question 8

Elective treatment of renal tract stones

Answer 8

• Extracorporeal shock wave lithotripsy (ESWL).
• Percutaneous nephrolithotomy (PCNL).
• Endoscopic treatment.: Ureteroscope is inserted and the stone visualized.
• Open nephrolithotomy/ureterolithotomy

Question 9

Treatment of ureteric obstruction

Answer 9

Emergency presentation
• Emergency treatment is indicated if there are signs of infection, established renal failure, uncontrollable symptoms.
• Treatment is drainage of the kidney via a percutaneous nephrostomy or retrograde ureteric stent.

Elective presentation
• Definitive treatment is directed at the underlying cause. Possible interventions include:
• Treatments of calculi
• Ureteric stenting (unilateral or bilateral).
• Ureterolysis and ureteric transfer (for retroperitoneal fibrosis).
• Prostatic resection.
• Bladder drainage using a urethral or suprapubic catheter.

Question 10

Causes of unilateral hydronephrosis

Answer 10

• All causes of unilateral obstruction may cause bilateral hydronephrosis.
• Congenital posterior urethral valve.
• Congenital or acquired urethral stricture.
• Benign enlargement of the prostate.
• Locally advanced prostate cancer.
• Large bladder tumours.
• Gravid uterus.

Question 11

Causes of bilateral hydronephrosis

Answer 11

Extramural.
• Aberrant vessels at the PUJ.

• Extrinsic tumour. Carcinoma of the cervix, prostate, large bowel, or retroperitoneal endometriosis.
• Idiopathic retroperitoneal fibrosis.
• Post-radiation fibrosis.
• Retrocaval ureter.
• Abdominal aortic aneurysm.

Intramural.
• Transitional cell carcinoma of the renal pelvis or ureter.

• Urinary calculi.
• Ureteric stricture.
• Aperistaltic segment. Almost always congenital.