Urolithiasis Flashcards by jared Jensen

Where can urolithiasis

anywhere in the urinary system
-kidney
-ureters
-bladder
-urethra

more than one place

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How might you localize where urolithiasis occurs radiographically

Laterals
VD
Obliques
Buttshots

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What is the best tool to localize urolithiasis

Radiographs

can pick up
1) Magnesium ammonium phosphate (Struvite)
2) Calcium oxalate
3) Silicate
4) Ammonium urate?
5) Cystine?

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What 5 stones can you pick up radiographically

1) Magnesium ammonium phosphate (Struvite)
2) Calcium oxalate
3) Silicate

4) Ammonium urate?
5) Cystine?

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What are your options to visualize radiolucent stones

1) Ultrasound * - typically lower urinary
2) Positive and Double Contrast studies
3) UA- USG, bacteria, WBC, crystals
4) Urine culture
5) Bloodwork - r/p obstruction, azotemia, electrolytes
6) POCUS- free fluid and run creat/K+
7) Renal function tests - USG / GFR
8) ECG if hyperkalemic

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what stones are radiolucent

Urates

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What are the indications of urolithiasis for surgery *

1) Obstructions of urinary flow
2) Refractory to medical treatment (struvite, urate, cysteine)
-Silica, calcium oxalate, calcium phosphate
-Increasing size
3) Nephroliths and renal dysfunction
4) Anatomical defect
5) Owner compliance

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Most commonly, urolithiasis occurs in

the urethra or ureter as these are smaller tubes

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What stones might medical treatment via dissolution be favorable for

Struvite
Urate
Cysteine

if they are refractory then there is indication for surgery

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What stones are you unable to dissolve

Silica
Calcium oxalate
Calcium phosphate

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Nephroliths are only removed if

they cause active renal dysfunction

test for renal function
-BUN, creatinine
-USG
-Perfusion and GFR

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T/F: nephroliths always affect renal function

False

test for renal function
-BUN, creatinine
-USG
-Perfusion and GFR

if evidence is there then you might need to remove it

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Nephroliths might predispose a dog to

pyelonephritis

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What do you do for a patient with bilateral nephroliths

Stage it
-do best kidney first
3-4 weeks between surgeries

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What are the surgical options for nephroliths

1) Nephrotomy- incision into the kidney to remove the stone

2) Pyelolithotomy- incision into the renal pelvis to remove the nephrolith

3) Nephrectomy - not a good option

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Following nephrotomy, kidney function might be reduced to

10-50% (might be temporary or long-term)

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How do you perform nephrotomy

1) Occlusion of blood supply (temporary)
2) Incision on convex surface (greater curvature)
3) Flush ureter and renal pelvis
4) Suture renal capsule

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What are the effects of pyelolithotomy

Dilation of the renal pevlis

less effect on renal function as the renal blood supply is not occluded

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Why does a pyelolithotomy have less effects on renal function when compared to nephrotomy

because you do not need to occlude renal blood flow

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Nephroscopy can be done if

there is dilation of the renal pelvis

use 1.9mm scope in renal pelvis with saline

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When is surgery for ureteroliths indicated

1) If not improving after serial radiographs or ultrasounds

2) Complete renal obstruction as you get complete loss of renal function after 4 weeks and ureteral necrosis and stricture can occur

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What are the results of a complete ureteral obstruction

complete loss of renal function after 4 weeks

ureteral necrosis or stricture

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What are the surgical options for ureteroliths

1) Pyelolithotomy- go through the renal pelvis and flush

2) Ureterotomy +/- stent : incision into ureter

3) Reconstruct the ureter
-reimplantation +/- stent
-bladder tube

4) Subcutaneous Ureteral Bypass - not good option

5) Nephrectomy and ureterectomy - not a good option

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What is needed to do Pyelolithotomy

dilated renal pelvis and hydroureter

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What is a pyelolithotomy for ureter obstruction

where you make an incision into the renal pelvis (patient needs to have dilated renal pelvis and hydroureter) do retropulsion flush from bladder into renal pelvis

What species is Uretertomy +/- stent preferred in

Dogs > Cats cats dont tolerate pigtail stents - dysuric

Uretertomy +/- stent can be done for ureters with

only 1 or 2 stones

What are complications of surgery for ureteroliths

1) Uroabdomen commonly transient, just remove with drain 2) Swelling obstruction 3) Stricture - obstruction

What is ureter reconstruction

where you ligate section of ureter that has obstruction, cut off, and suture ureter back to bladder, resulting in shorter ureter not commonly done

What is Subcutaneous Ureteral Bypass (SUB)

a complete bypass where tubing is attached from kidney to connector to bladder life long medical management -infection -encrustation -migration -kinking port that goes outside allows you to flush and collect urine has to be flushed frequently for life

What are the risks from Subcutaneous Ureteral Bypass (SUB)

life long medical management -infection -encrustation -migration -kinking has to be flushed frequently for life

Nephrectomy + ureterectomy depends on

other kidney function multiple uroliths *Not a good option for urolithiasis

What are tips for retropulsion of urethral stones in dogs

-general anesthesia -large rigid catheter -gauze to grip penis (pinch) -sterile lubricant (lots of it) and saline -extra finger for a -rectal if needed -post procedure radiographs

where you flush stones from the urethra back into the bladder

retropulsion

retropulsion for urehtral stones works

90-95% of the time

Why it is recommended to do retropulsion of urethral stones with general sedation

sedation might work but general anesthesia is recommended to relax

What cather is recommended for retropulsion

Large rigid catheter

Why should you do post procedure radiographs after retropulsion for urethral stones

you cant always tell you got all of the stone with a catheter they like to hide in the ischial arch

What should you do if you cant do retropulsion of urethral stones

Urethrotomy: first time or Urethrostomy: multiple obstructions

T/F: most urethral calculi can be retropulsed into the bladder

True

Urethrotomy is for _______ while urethrostomy is for ________

UrethroTOMY: first time UrethroSTOMY: multiple (or cat)

T/F: you can do urethrotomy in cats

false- their urethra is too small to open and close again

Urethrostomy is indicated for

Dogs with multiple urethral obstructions or cats

Surgical procedure to make a large urethral opening

Urethrostomy

Surgical procedure to open urethra, take stone out, and close again

Urethrotomy

Why is a urethrostomy done in the scrotal area, as opposed to the pre-scotal area

-Large area -Superficial -tension free -limits hemorrhage -minimizes urine scale -dont necessarily have to remove penis

How does the approach for a urethrostomy differ in dogs vs cats

Dogs: Scrotal Urethrostomy Cats: Perineal Urethrostomy (PU)

What are the benefits of doing urethrostomy in cats with a perineal approach

1) Larger urethral opening 2) Minimizes tension 3) Dissect to the level of the bulbourethral glands (dogs dont have this) 4) Removes penis

When doing a Perineal Urethrostomy (PU) in cats you need to dissect down to the

Bublourethral glands

What approach is a cystotomy performed on

ventral cystostomy ideally stones are retropulsed into the bladder for removal

When doing a cystotomy, why is it important to start with a urinary catheter in place

so the stones dont go into the urethra during surgery

What approach is a cystotomy done in male dogs

caudal midline and parapreputial approach -deeper incision at linea alba

When doing cystotomy where do you want to incise the bladder

at the median ligament

When doing a cystotomy where are stay sutures placed

Apex and neck also helpful in side

When doing a cystotomy you make a stab incision and extend with scissors from the

neck to the apex

What should you do after removing stones when doing a cystotomy

1) Flush retrograde 2) Flush normograde both through the urethra this ensures you remove residual minerals go until you dont feel any gritty

How do you close a cystotomy

4-0 Monofilament rapidly absorbable suture Taper needle Full thickness bite 3mm apart and from edge submucosa = holding later simple continuous, appositional

What is the holding layer when doing a cystotomy

Submucosa

With cystotomy closure, full thickness defects gain 100% of normal strength in

14-21 days can use small monofilament that is rapidly absorbed ie Monocryl, Biosyn

When closing cystotomy, how far should your bites be

3mm apart and from edge

What needle should you use when suturing a cystotomy

Tapered (cutting makes bigger hole in bladder)

T/F: dont do full thickness closure in cystotomy

False - you need to go full thickness because you if you get the mucosa then you will get the submucosa (holding layer)

T/F: full thickness cystotomy suture closure results in long terms bladder mucosal changes

False - you should go full thickness to make sure you get the submucosa

What should you do after closure of cystotomy

Post-operative radiographs to confirm stones not present in the bladder or the urethra if you see stones, go back to surgery

After cystotomy, what post operative care should you do

-IV fluids, flush blood clots from the bladder / urethra -Opioids (PRN while hospitalized) -NSAIDs 5-7d -Gabapentin 7-10d -Buprenorphine (cats) +/- Prazosin if significant spasm or straing

What drug should you give if the patient is having significant spasm or straining after cystotomy

Prazosin

What diagnostics should you do for removed stones

Stone Analysis at Minnesota Urolith Center Culture - treat as needed Follow up medical management: diet and urine pH

How long should you wait to recheck after cystotomy

10-14 days follow up on stone analysis and make recommendations for further treatment, diet, diagnostics, and follow up

What are cystotomy complications

-Superficial incisional complications - 4% -Uroabdomen due to suture failure <1.5% -Self resolving hematuria and dysuria 37-50% -Incomplete urolith removal 14-20%