Urinary Tract Calculi

Question 1

What are urinary tract calculi formed from.

Answer 1

Crystal aggregates.

Question 2

Where do renal stones for.

Answer 2

Stones form in the collecting ducts and may be deposited anywhere from the renal pelvis to the urethra.

Question 3

What are the three classical locations for renal stones to get stuck. (3)

Answer 3

Pelviureteric junction.
Pelvic brim.
Vesicoureteric junction.

Question 4

What is the lifetime incidence of renal stones.

Answer 4

15%.

Question 5

What is the peak age for renal stones to develop.

Answer 5

20-40.

Question 6

What is the male:female ratio for renal stones.

Answer 6

3:1.

Question 7

What type of renal stones are there. (7)

Answer 7

Calcium oxalate (75%). 
Magnesium ammonium phosphate (struvite/triple phosphate) 15%. 
Urate (5%). 
Hydroxyapatite (5%). 
Brushite. 
Cystine (1%). 
Mixed.

Question 8

What are the typical presentations of renal stones. (13)

Answer 8

Asymptomatic, 
Renal colic. 
Renal obstruction. 
Obstruction of mid-ureter. 
Obstruction of lower ureter. 
Obstruction in bladder or urethra. 
UTI. 
Haematuria. 
Proteinuria. 
Sterile pyuria. 
Pyonephritis. 
Pyonephrosis. 
Anuria.

Question 9

What are the features of renal colic. (3)

Answer 9

Loin to groin pain.
Nausea/vomiting.
Patient cannot lie still (differentiates from peritonitis).

Question 10

What are the features of renal obstruction. (3)

Answer 10

Felt in the loin (between rib 12 and lateral edge of lumbar muscle).
Not colicky, more like nerve irritation.
Worse with specific movement, pressure on the specific location.

Question 11

What are the features of obstruction of mid ureter.

Answer 11

The pain mimics that of diverticulitis/appendicitis.

Question 12

What are the features of obstruction of lower ureter by a renal stone. (2)

Answer 12

May lead to symptoms of bladder irritability.

Pain in scrotum, penile tip or labia majora.

Question 13

What are the features of obstruction in bladder or urethra caused by a renal stone. (4)

Answer 13

Pelvic pain.
Dysuria.
Strangury (desire to void, but inability to do so).
Interrupted flow.

Question 14

What are the features of pyelonephritis. (5)

Answer 14

Fever. 
Rigors. 
Loid pain. 
Nausea. 
Vomiting.

Question 15

What is pyonephrosis.

Answer 15

Infected hydronephrosis.

Question 16

What are the features on examination of a patient with renal stones. (3)

Answer 16

No tenderness on palpation.

May be renal angle tenderness (especially to percussion if there is retroperitoneal inflammation).

Question 17

What blood tests are usually done in a patient with renal stones. (7)

Answer 17

FBC. 
UandEs. 
Calcium. 
Phosphate. 
Glucose. 
Bicarbonate. 
Urate.

Question 18

What is the usual result of a urine dipstick in a patient with renal stones.

Answer 18

Positive for blood (90%).

Question 19

Why is an MSandC done in suspected renal stones.

Answer 19

To rule out infective cause of pain (eg UTI).

Question 20

What is the imagine technique of choice for detecting a renal stone.

Answer 20

Spiral non contrast CT (99% of stones are visible).

Question 21

If a KUB XR is done in a patient with suspected renal stones, where do you look on the film for the stones.

Answer 21

Along the ureters for calcification over the transverse processes of the vertebral bodies.

Question 22

What is the initial management for a patient with renal stones. (3)

Answer 22

Analgesia (diclofenac PR is the best pan relief).
IV fluids.
Antibiotics (cefuroxime or gentamicin) if infected.

Question 23

What is the management for stones

Answer 23

90-95% will pass spontaneously.

Increase fluid intake.

Question 24

What is the management for stones >5mm which are causing pain and not resolving. (6)

Answer 24

Medical expulsion therapy:
Nifedipine PO or alpha blocker promote expulsion and reduce analgesia requirements.
Start treatment at presentation.
Most will pass within 48h (>80% after 30 days).
ESWL if

Question 25

What is ESWL.

Answer 25

Uses ultrasound waves to shatter the stone.

Question 26

What are the potential side effects of ESWL. (3)

Answer 26

Renal injury.
DM.
Raised BP.

Question 27

What are the indications for urgent intervention in the case of renal stones. (6)

Answer 27

Presence of infection and obstruction. 
Urosepsis. 
Intractable pain or vomiting. 
Impending ARF. 
Obstruction in a solitary kidney. 
Bilateral obstructing stones.

Question 28

What are some general methods for preventing renal stones. (2)

Answer 28

Drink a lot of water.

NORMAL dietary calcium intake.

Question 29

What will a calcium oxalate stone look like on XR. (2)

Answer 29

Spiky.

Radio-opaque.

Question 30

What will a calcium phosphate stone look like on XR. (3)

Answer 30

Smooth.
May be large.
Radio-opaque.

Question 31

What will a magnesium ammonium phosphate stone look like on XR. (3)

Answer 31

Large.
Horny ‘staghorn’.
Radio-opaque.

Question 32

What will a urate renal stone look like on XR. (3)

Answer 32

Smooth.
Brown.
Radiolucent.

Question 33

What will a cystine stone look like on XR. (3)

Answer 33

Yellow.
Crystalline.
Semi-opaque.

Question 34

What are some risk factors for renal stone development. (7)

Answer 34

Diet (foods rich in oxalate will increase stone formation).
Medications (diuretics, antacids, aspirin, allopurinol).
Recurrent UTIs.
Metabolic abnormalities (hypercalciuria, hypercalcaemia, cystinuria, hyperoxaluria, renal tubular acidosis).
Urinary tract abnormalities (horeshoe kidney, spnge kidney).
Foreign bodies (stents, catheters).
Positive FH.

Question 35

What are the signs of an infection above a renal stone. (3)

Answer 35

Fever.
Loin tenderness.
Pyuria.