Urinary tract calculi

Question 1

What are the three classic locations that renal stones are deposited at?

Answer 1

The renal pelvis
As the ureter passes the pelvic brim
As the ureter enters the bladder

Question 2

What are the different types of urinary tract stones? do they show up on x ray and what causes them?

Answer 2

• calcium oxalate (75%) - Spikey, radio-opaque - caused by hypercalcuria
• Magnesium ammonium phosphate (struvite) (15%) - Staghorn radioopaque - caused by UTI often associated with chronic infections
• Calcium phosphate (10%) - smooth, radioopaque - caused by low urine pH
• Urate (5-10%) - radiolucent - caused by high urea in urine

Question 3

What are the presenting features of urinary tract stones?

Answer 3

Pain - excruciating loin to groin with N and V - lower ureter may refer to the scrotum or bladder
Infection - can coexist - increased risk if voiding impaired
Haematuria
Proteinuria
Anuria

Question 4

What tests should be done for urinary tract stones?

Answer 4

Bloods - FBC, U and E, Calcium, glucose, bicarb
Urine dip for blood and protein
MSU - culture and sensitivity
Can test urine for specific cause of stone

Question 5

What is the treatment of urinary tract stones?

Answer 5

Initially analgesia (PR diclofenac) with fluids (IV if not tolerated orally)
Antibiotics if infection
Stones <5mm in lower ureter mainly pass spontenously
>5mm may need medical therapy e.g. alpha blocker tamsulosin
If this does not work in 48hrs then consider extracorporeal shockwave lithotripsy (US)
If this does not work then can do percutaneous nephrolithotomy

Question 6

What are the indications for urgent surgical intervention in renal stones? how is this treated?

Answer 6

If there is infection and obstruction as this kills glomeruli
Treat with percutaneous nephrostomy or ureteric stent

Question 7

How are urinary tract obstructions usually classified? give some examples?

Answer 7

Luminal e.g. stones, clots, tumour
Mural e.g. strictures, neuromuscular dysfunction
Extramural e.g. abdominal mass, retroperitoneal fibrosis

Question 8

What investigations should be done for urinary tract obstruction?

Answer 8

Blood, urine dip and MC and S

Ultrasound - if any hydropnephrosis or hydroureter then do CT to work out level of obstruction

Question 9

What is the treatment of upper urinary tract obstruction?

Answer 9

Nephrostomy or ureteric stent

Question 10

What are some of the problems of ureteric stenting?

Answer 10

Stent related pain
Bladder trigone irritation
Haematuria
Fever
infection
Tissue inflammation

Question 11

Best way to prevent stones?

Answer 11

Increase fluid intake