Cystic Calculi

Question 1

Two other names for cystic calculi

Answer 1

uroliths

bladder stones

Question 2

What uroliths are most common?

Answer 2

calcium oxalate

struvite (aka magnesium ammonium phosphate, triple phosphate)

Question 3

How do cystic calculi form?

Answer 3

Start out as simple crystal nidus

Question 4

What can cause the formation of a simple crystal nidus?

Answer 4

excessive excretion of crystal-forming substance (mineral or certain proteins) into the urine and/or change of urine pH

Question 5

What happens if a simple crystal nidus remains in the urine?

Answer 5

more mineral and protein build upon it turning it into a stone

Question 6

How do stones affect lower UT?

Answer 6

• can pass through just fine if small enough
• partial or complete obstruction of urethra if they get stuck
• direct damage to bladder mucosa causing local inflammation and possible hemorrhage
• decreased defense of bladder which increases risk of bacterial infection
• chronic irritation and inflammation may result in hyperplasia of bladder wall

Question 7

Clinical sign of stones and the reason

Answer 7

• same as lower UT Dz (hematuria, dysuria, stranguira, pollakiuria)
• result from constant irritation and inflammation of urinary bladder wall by the mechanical presence of the stones

Question 8

How is diagnostic imaging useful to confirm presence of stones?

Answer 8

Rads

• detects stones >3mm in diameter to indicate size and number
• ammonium urate stones are radiolucent

Ultrasound
-can ID almost every urolith regardless of composition, number, and size

Question 9

Medical management options

Answer 9

• dietary manipulation of urine pH to a level that will not support super-saturation of minerals in the urine
• dissolution of stones (if struvite) with dietary change
• control of bacterial cystitis if present
• removal of stones via voiding urohydropulsion or via catheter retrieval

Question 10

Surgical management

Answer 10

• Cystotomy +/- urethrostomy manually removes stones

- does not treat underlying cause via just Sx management

Question 11

What post-op procedures should follow Sx removal of stones?

Answer 11

• immediate post-op rads to confirm stone removed
• recovered urolith submitted to lab for complete analysis including culture and determination of mineral composition
• development of medical management plan after getting results

Question 12

Basic medical management recommendations for struvite

Answer 12

• likes basic environment, so promote a more acidic pH (6-6.5)
• restrict dietary protein
• increase water intake
• treat any bacterial UTI that is present

-if dissolving thru diet change, monitor P with rads or US to make sure stones are decreasing in size and aren’t getting stuck in urethra

Question 13

Basic medical management recommendation for calcium oxalate

Answer 13

• prefers acidic environment, so change diet to promote a more neutral pH (6.5-7)
• not dissolvable with dietary management
• don’t feed excessive calcium
• increase water intake