Urology

Question 1

What is a Tc-DMSA scan

Answer 1

Static renal scintigraphy
DSMA dye is taken up by the functioning tubules
Shows areas of scarring/ infarction or masses
Also shows areal of congenital abnormalities - small kidney with globally reduced uptake
Can be used to estimate GFR

Question 2

What is a MAG3 Renogram / DTPA

Answer 2

both renal scintigraphy studies
Dye is given which binds to albumin and is excreted by the kidney. When the concentration of MAG3 in the blood and excretion via the kidney is equal = produces a time curve = renogram.
This can be used to determine if there is any split function between the kidneys
DTPA = filtered by the glomeruli and gives a perfusion index to evaluate excretion

Overall MAG3 has high renal extraction and preferred agent fort imaging

Question 3

What is a retrograde Ureterography scan

Answer 3

Looks at any filling defects / reflux / stones

Question 4

Radiolucent stones

Answer 4

Uric acid
Drugs - acyclovir

Question 5

Causes of Oxalate stones

Answer 5

Malabsorption / short bowel syndrome
Ethynyl glycol
Vitamin C

Question 6

Stones associated with malabsorption

Answer 6

Calcium oxalate
Acidic
White /pale stones
Appear multicoloured biferfrignece under polarized light, appear fan / rhomboid shaped

Question 7

Stones associated with obesity

Answer 7

Uric acid stones
Acidic, translucent
Diamond / needle shaped, positive birefringence under polarized light

Note - aciclovir crystals also appear needle shaped and positive under polarized light

Question 8

Cysteine stones

Answer 8

Hexagonal. acidic
Occur in fanconis / positive FHx - occur in young patients
Tx - Tiopronium or D-penicillamine

Question 9

Struvate stones

Answer 9

Staghorn
Alkaline stone
AKA ammonium magnesium stone
Occur from recurrent infection - proteus and Klebsella

Question 10

Acidic versus alkaline stones

Answer 10

Acidic
-Calcium oxalate
-Uric acid
-Cysteine

Alkaline
-Calcium phosphate
-Struvate

Question 11

Stone seen in RTA 1

Answer 11

Calcium phosphate
Needle shaped
Alkaline stones

Question 12

Treatment of stones

Answer 12

Lifestyle changes - drink water, reduced salt, low protein
Thiazide diuretic - indapamide
Potassium citrate to alkaline the urine

treatment of oxalate stones - increase calcium intake

Question 13

Indication for prophylactic antibiotics in UTI

Answer 13

Asymptomatic recurrent UTI - no benefit in treating

If UTI related to sexual activity - trimethoprim or nitro are options
Other unknown causes for recurrent UTI - Tx with monthly rotation of nitro/ trimethoprim / cefalexin
Give prophylaxis for 1 year then review

Question 14

Indication for surgical treatment of stones

Answer 14

If <10mm then for medical expulsive therapy
If 10-20 then for Extracorporeal shockwave lithotrispsy (ESWL)
If >20 then for percutaneous nephroplithotomy (PCNL)

Note - mean density of >800HU less likely to be fragmented and may need flexible ureteroscopy to collect the stone if <20mm

Question 15

Idiopathic hypercalcinuria

Answer 15

Autosomal dominant, strong FHx
Causes recurrent stones in young children and parents

Question 16

Management of calcium oxalate stones

Answer 16

Increase calcium intake = helps bind to intestinal oxalate and reduce stone formation

Question 17

Treatment of mixed oxalate and uric acid stones

Answer 17

Reduce protein intake

Question 18

Tests used to look at renal function

Answer 18

Static renal cortical imaging - DMSA - look for scarring and differences in renal function
Dynamic renal imaging - DTPA, MAG3

Question 19

Differences between MAG 3 and DTPA

Answer 19

MAG 3 = can look at renal function, blockages / split function. It cant measure GFR though as its cleared by tubular secretion

DTPA = Can be used to measure GFR as its cleared by the glomeruli. Used for renal performance measure in potential kidney donors

Question 20

Cause of medullary and cortical stones

Answer 20

hyperoxaluria/ oxalosis

Question 21

Commonest composition of idiopathic stones

Answer 21

Calcium Oxalate