Surgery of the Urinary Tract Flashcards
Green LO What metabolic derangements besides azotemia are commonly seen and may need to be corrected prior to surgery in animals with chronic or acute kidney injury? List 6
- Azotemia
- Hyperphosphatemia
- Metabolic acidosis (from uremia)
- Anemia due to decreased EPO
- Oliguria or polyuria
- Dehydration
- Electrolyte abnormalities
- Hypercoagulability in protein losing disease (due to antithrombin III loss)
- Infection
Why is chromic gut a poor choice for suture material?
- Increased inflammatory reaction
- Poor predictability of breakdown
Why is absorbable suture recommended for surgery in the urinary tract?
- Monofilament has less tissue drag
- Non-absorbable may provide a nidus for calculi formation
Green LO WHat is normal urine production for a hydrated animal on IVF?
- > 2 mL/kg/hr
How does the kidney heal?
- Parenchyma - scar tissue with few adverse consequences
- Loss of nephrons
- Pelvis and collecting ducts can lead to structures
What part of the kidney do you want to avoid with surgery?
- Medulla
Green LO Healing of the ureters
- Strictures and leakage are COMMON
Green LO Healing of the bladder
- Heals quickly and COMPLETELY
Green LO Healing of the urethra
- Defects (not transection) heals by 2nd intention in 7-10 days but only with urinary diversion
Green LO Why is nonabsorbable suture contraindicated in the urinary tract?
- Nidus formation is major
How does urine affect wound healing?
- Increased inflammation
- Increased risk of stricture formation
- Potential for delayed wound healing
What is it important to obtain with urinary tract surgery to avoid urine complicating wounds?
- A water tight seal!
Green LO How common are complications to renal biopsy?
- 13-19% complication rate
- Cats are more likely than dogs (I think due to size)
Green LO Which groups of patients are more likely to experience complications after renal biopsy? List 3
- Animals under 5 kg (cats!)
- Older patients
- Patients with severe azotemia
Clicker question: Renal biopsies should not be performed indiscriminately. Which of the following is NOT a good indication for biopsy?
A. Differentiation of protein-losing glomerular diseases
B. Differentiation of ARF from CRF
C. Determination of treatment response in protein-losing disease
D. Staging of chronic kidney disease
D. Staging of chronic kidney disease!
Renal biopsy technique options
- FNA
- Needle biopsy (True-cut)
- Wedge
When to do FNA of the kidney?
- Suspect neoplasia or pyelonephritis
- Closed or ultrasound guided
More about needle biopsy (Tru-cut) for kidney
- Percutaneous
- Laparascopic or open surgery will result in better quality
Wedge biopsy of kidney - how to do? when indicated?
- Open only
- RARELY indicated
Green LO What three diagnostic tests should be performed on renal biopsies?
- Biggest/best piece in formalin; view with light microscopy
- Frozen: immunofluorescent or histochemical microscopy
- Fixative for electron microscopy
- Ask for kits from the lab
Green LO In which patients are renal biopsy contraindicated? List 5 distinct and one relative contraindication
- Coagulopathies
- Uncontrolled hypertension
- Pyelonephritis
- Cysts
- Obstructive uropathy
- Relative is animals under 5 kg
Indications for renal biopsy
- Persistent proteinuria, glomerular disease
Green LO Which clinical pathological finding is most often associated with the need for a renal biopsy?
- Proteinuria
At what common renal condition is renal biopsies not indicated (but not necessarily contraindicated)?
- Chronic kidney disease
Green LO What type of biopsy needle is recommended for renal biopsy?
- Tru-cut spring-loaded needle
Green LO How is the biopsy needle oriented?
- See images
- Basically stay in the cortex
- It’s a very shallow angle
Green LO What are common reasons that obtained renal biopsies are non-diagnostic? List 5
- Placed the biopsy needle too deep (few glomeruli or transect an arcuate vessel)
- Wrong angle
- Inadequate amount of cortical tissue
- Need two more???
Green LO Mention 2 serious complications occurring due to malpositioned biopsy needles?
- Transection of an arcuate vessel (went too deep)
2. If you take a biopsy near the renal pelvis, you can cause extravasation of urine
Blue LO Before nephrectomy, what diagnostic test is not readily available, but the only way to ensure the patient will tolerate losing the kidney?
- Assessment of GFR to demonstrate function
- GFR markers (inulin clearance, SDMA, etc.) do not show individual renal contribution
- Renal nuclear scintigraphy can help you distinguish individual kidney function
Blue LO Which tests can give a good indication that the remaining kidney is functional?
- Ultrasound with doppler or contrast IV pyelogram
- This indicates function but does not how function
Blue LO Know how to perform an “air” nephrectomy. Surgical performance key words
- Open the retroperitoneal space (start laterally) to expose the artery first. Identify all branches and double ligate with absorbable suture close to the abdominal aorta to ensure that all branches have been ligated. Consider transfixation suture if the artery is larger than 3-4 mm in diameter.
- Identify and ligate the renal vessels (artery first, then vein)
- Dissect the ureter as it comes out of the bladder wall
- Submit for histopathology and culture
Renal calculi - when are they found
- Often found incidentally during workup for cystic calculi
Blue LO What are the clinical signs of nephroureteroliths in dogs?
- May present with hematuria
- May present with renal or ureteral obstruction/azotemia
Blue LO Why do nephroliths pose a treatment dilemma for clinicians?
- Clinically silent
- Affected animals may have pain, fever, and/or renal failure attributable to urinary outflow obstruction, fibrosis, or infection
- Clinical signs of ureteroliths may be nonspecific and discovered incidentally
Blue LO When should removal of nephroliths be considered?
- Increasing size (follow nephroliths 3 months later)
- Associated pyelonephritis
- Evidence of obstruction (hydronephrosis)
- Severe hematuria
- The presence ALONE s not an indication for surgery
BLACK LO Which are the two surgery types for removal of nephroliths while keeping the kidney?
- Nephrolithotomy
- Pyelithotomy (preferred technique)
Black Description of nephrolithotomy
- Temporary vascular occlusion
- Midline longitudinal nephrotomy
- Digital apposition/capsular closure
- Leads to 30-50% reduction in renal function (transient)
- Minimally invasive technique also described
Blue LO Four indications for nephrectomy?
- End-stage hydronephrosis
- Renal neoplasia
- Uncontrolled primary renal hemorrhage
- End-stage pyelonephritis
Blue LO Which diagnostic test shows high sensitivity in detection of nephroureteroliths?
- Ultrasound is much more sensitive than abdominal radiograph
Green LO What is the difference between chronic kidney disease and chronic renal failure?
- Chronic kidney disease refers to patients with a permanent loss of functioning nephrons that have had renal damage, with or without a decreased GFR for at least 3 months, or that have had a 50% reduction of GFR for at least 3 months
- Chronic renal failure is a progressive disease that occurs in patients with CKD with significant clinical signs (PU/PD, weight loss, decreased appetite) and lab findings (azotemia, anemia, proteinuria)
Green LO Why is it easy to confuse acute with chronic kidney injury?
- Animals with CRF or CKD can become acutely worse if reasons for acute injury are superimposed upon the chronic condition (i.e. acute on chronic kidney failure)
Green LO What diagnostic tests are used to stage chronic kidney disease? List 3 PE findings or diagnostic tests (just the test not the levels)
Step 1: Fasting plasma creatinine assessed on at least 2 occasions in the stable patient
Step 2: Substaged based on proteinuria and blood pressure
Blue LO What are the 3 major complications to renal surgery?
- Hemorrhage (check PCV post-op)
- Renal failure
- Urinary leakage (measure by abdominocentesis and subsequent comparison of fluid and serum creatinine)
Blue LO What are the 2 major complications to ureteral surgery?
- Ureteral blockage
2. Urinary leakage
Blue LO Which type of nephrolith/ureterolith has increased over the last 20 years?
- Calcium oxalate
Blue LO How often are nephro or ureteroliths bilateral?
- 25% of affected cats and 20% of dogs
Blue LO Why should nephroliths not always be removed?
- Removal of uninfected stones from the kidney may result in more damage than is caused by the stones themselves
- Medical therapy may help dissolve
- Need to know renal function in the affected and contralateral kidney
- Animal’s overall health
What are the clinical signs of ureteroliths in cats?
- Hematuria is often the clinical sign noted in cats with nephrolithiasis
Blue LO In which cases can nephrectomy be considered for nephroliths? List 4.
- Nephrectomy is indicated in non-functional kidneys
- NOT SURE THE OTHER FOUR probably ask someone
Blue LO How do you decide between nephrectomy versus stone removal?
- I think this would basically be if the kidney is functional or not
Blue LO WHat is the inherent risk of removing the kidney for obstructive nephroureteroliths. List 2.
- 20-25% are bilateral, or there could be recurrence.
- If you’re not sure if the contralateral kidney is functional, you could push the animal into overt renal failure
What is an ectopic ureter? Where do they typically enter?
- Abnormal development of ureteral openings
- Bypass bladder trigone
- Enter urethra or (rarely) vagina
Blue LO What is the most common age of ectopic ureters?
- Female dogs usually at a young age (10 months)
- Males tend to be a bit older (12-24 months)
Blue LO What is the most common sex associated with ectopic ureters?
- Females predisposed (10-20:1)
Blue LO What are the common clinical signs associated with ectopic ureters?
- Congenital incontinence
- Recurrent UTI
Blue LO Explain why ectopic ureter cannot be ruled out in animals with normal urination volumes or only intermittent incontinence
- Affected dogs with ectopic ureters opening near the sphincter may have some response to medical management, mimicking dogs with acquired urinary incontinence.
What are the most common forms of ectopic ureters?
- Intramural ectopic ureters
Where do intramural ectopic ureters form?
- Serosal surface of the bladder trigone
- Passes submucosally into the urethra
Where do extramural ectopic ureters enter?
- Bypass bladder neck and go directly into the urethra or vagina
Prognosis for ectopic ureter correction
- 50% have resolution of clinical signs
- 50% have some degree of residual incontinence either due to failure to occlude te distal ureter OR urethral sphincter mechanism incompetence**
How long to allow recovery of function after correction of an ectopic ureter?
- 2-3 months to evaluate recovery
- Rule out USMI
What drugs to consider if still incontinent after correction of ectopic ureter?
- Phenylpropanolamine (PPA) with or without diethylstilbestrol
Green LO Are uroabdomen and urinary obstruction considered medical or surgical emergencies?
- MEDICAL emergencies
- Immediate surgery is contraindicated
- Non-emergency surgery when stabilized
Green LO What electrolyte abnormality associated with uroabdomen and urinary obstruction needs to be corrected before anesthesia, and why?
- Hyperkalemia!
- Causes bradycardia, tall tented t waves, possible atrial standstill
- Absent or flattened P waves
- Prolongation of the P-R interval
Green LO What are the pathophysiological consequences of plasma potassium concentrations exceeding 7 mEq/L and with 9 mEq/L?
- 7 mEq/L: irregular idioventricular rhythm
- 9 mEq/L: atrial standstill
Green LO How do you treat hyperkalemia in urethral obstruction?
List two treatment strategies.
- Mild to moderate may be treated with IV fluids (LRS, Normosol-R and 0.9% saline are effective)
- Elimination of the obstruction (e.g. urethral catheterization or decompressive cystocentesis). Can do retrohydropropulsion, retrograde catheterization.
Green LO How do you treat hyperkalemia in uroabdomen?
List two treatment strategies.
- Abdominal drainage. Retrograde catheterization.
- IV fluid therapy (0.9% saline, LRS, Normosol-R)
Green LO In addition to fluid therapy, how can life-threatening hyperkalemia be treated and how often are these treatments indicated?
- Dilute by giving physiologic 0.9% saline solution IV, or, once the obstruction is relieved, LRS IV
- If necessary to lower potassium immediately give sodium bicarbonate or regular insulin plus dextrose
- If hyperkalemia is immediately life threatening, may give 10% calcium gluconate for transient cardiac protection. Give slowly (over 5-10 min) while monitoring the patient’s ECG
- Provide intubation and controlled hyperventilation to rapidly reduce respiratory acidosis
Green LO What are the two strategies of timing for antibiotic treatment in cystic or urethral calculi?
- Ideally want antibiotics in place prior to surgery based on C&S results
- If no culture, obtain intra-op, and start IV antibiotics after obtaining the sample of the bladder wall and stone
- Intra-op culture is not necessary with positive pre-op culture
- Stone analysis should always be performed
Green LO Which intraoperatively obtained samples are more likely to yield bacterial growth if urine cultures have been negative? List 2.
- Bladder wall
- The stone itself
When might you suspect uroabdomen clinically?
- Lack of urination following injury
- But don’t rule out bladder rupture in animals that urinate normal volumes
Green LO Which diagnostic procedures may detect uroabdomen in vehicular trauma patients?
- Radiographs
- FAST scan
- Positive contrast cystourethrogram with retrograde flush
Green LO Why is fluid and serum creatinine helpful in the diagnosis of uroabdomen but not fluid and serum BUN?
- BUN equilibrates over membranes and is immediately reabsorbed
- Creatinine does not get reabsorbed
Green LO How is a uroabdomen diagnosed on fluid analysis?
- Creatinine in abdominal fluid is at least twice as high as that in peripheral blood
- Suggestive is if creatinine is >1 but <2
- Suggestive if potassium is higher in abdominal fluid than in peripheral blood
Green LO What is the most common cause of uroabdomen?
- Bladder rupture
- May occur spontaneously or by a blunt or penetrating abdominal trauma
Green LO When should surgery ideally be performed?
- Ideally once the patient is stabilized
- Retrograde catheterization
- +/- Peritoneal drainage
- IV fluids
Green LO If surgery needs to be delayed, which treatments need to be initiated in the interim?
- IVF
- Retrograde catheterization
- +//- peritoneal drainage
Green LO Be able to performan “air” retrohydropulsion in a male dog. Note key words to remember teh steps of the procedure.
- Distend urethra in pelvic canal with a finger in the rectum distal to the stoen
- Lube mixed with sterile water
- Lidocaine jelly (max imum of 2 mg/kG)
- Flush the urethra
Clicker Q Is a traumatic uroabdomen considered a medical or surgical emergency?
A. Medical; immediate med management is imperative. Surgery can wait.
B. Surgical: go to surgery without delay. 12 hour delay would be detrimental.
C. Neither. Ask owner to come in during regular hours.
A.
Anesthesia in retrohydropropulsion in cats vs dogs
- Cats: Propofol or coccygeal block
- Dogs: Anesthesia
Air retrohydropropulsion in cats
- Straighten penis (traction)
- Saline + water based lube
- Pulsatile infusion
- If large bladder, decompress first with cystocentesis
Where are three locations that stones get stuck in the dog?
- Os penis!**
- Prostatic urethra
- At the curve as the urethra reflects cranially
Healing potential of the bladder (more detail)
- How long does it take? What % of strength?
- Bladder heals to 100% strength in <21 days
Urethra healing
- Heals by 2nd intention if not completely transected and urine is diverted for 7-10 days
Green LO Why is nonabsorbable suture not recommended for the bladder?
MAY act as a nidus for stone formation
Green LO What suture pattern is sufficient for cystotomy closure?
- Single layer appositional closure
- Pressure test
- Appositional thought to be better than inverting, because it heals faster
Green LO What inadvertent error may occur while suturing a thin walled bladder and how serious is the consequence thought to be?
- Suture in the lumen
- Common in thin-walled bladders, but it is not believed to be associated with formation of calculus if absorbable monofilament suture is used
Green LO Which suture type is recommended for bladder and urethra?
- Absorbable monofilament
Common indications for urinary bladder surgery
- Bladder rupture
- vehicular trauma
- Necrotic bladder
- Urinary cystic calculi
- Neoplasia (depending on type)
Forgiveness of urethral surgery
- Non-forgiving (need perfect apposition and tissue handling)
Black LO What are the two most common complications of urethral wound repair?
- Stricture
- Leakage
Black LO How can partial defects heal?
- By second intention
- same with urethrotomy
- Just need a urinary diversion for 7-10 days either by u-cath or cystotomy tube
Describe cystotomy tube placement Green
- Midline celiotomy
- Purse string in the bladder
- Mushroom tipped catheter
- 4 suture pexy
Order of pexy sutures for cystotomy tube placement (maybe need clarification but need to know this)
- Dorsal
- Caudal
- Cranial
- Ventral
Place all as stay sutures. Tie when they are all in place, in the order above.
Green LO How are small urethral lacerations treated?
- I think they can heal by second intention??
- Just need to place a urethral catheter or tube cystostomy for 7-10 days
Black LO How is complete transection of the urethra treated?
- Ask
- I’m not sure
- I’m guessing urethrostomy and probably something to shorten the prepuce??? I DK
Green LO Be able to perform an “air” cystotomy
- Open
- Pack off with exclusion drapes
- Stay sutures in the cranial pole and laterally
- Ventral incision - ensure adequate exposure (at least 50% of the bladder)
- Stay on the bladder midline, as indicated by the median ligament
- SImple continuous closure (or with second inverting layer
- Urinary catheterization - pre vs intra op; flush retrograde into the bladder
- Leak test
Green LO What is the risk if you come off midline when doing a cystotomy?
- Cutting into a ureter!
Describe retrograde intraop catheterization in females.
- Take a red rubber into the bladder and out the urethra
- Then you have the vulva prepped and in the field
- Pull another catheter through the red rubber and blow up the foley bulb
What are your top four differentials for hematuria, pollakiuria, and stranguria?
- UTI
- Uroliths
- Neoplasia
- Trauma
Green LO How do you repair a ruptured bladder?
- Bladder rupture generally occurs near the apex
- Small ruptures may heal if the bladder is kept decompressed
Green LO Which two stone types are radio-opaque?
- Struvite and calcium oxalate
Green LO Which 2 stone types are the least radiopaque?
- Urate
- Cysteine
Green LO Which are common clinical signs of calculi? List 3.
- Hematuria
- Pollakiuria
- Stranguria
Signalment for oxalates
- Common
- Miniature schnauzers
- Cats
- Hypercalcemia
- Obesity
Signalment for struvite
- Common
- Associated with UTI in dogs but not in cats
Signalment for urate calculi
- Shunts/Dalmatians
Signalment for cystine calculi
- Dogs
- Rare in cats
Green LO Signalment for silicate stones
- German and Australian shepherds
- labs
Green LO Which disorder in many breeds lead to patients prone to form urate calculi?
- Portosystemic shunts
Green LO Which are the two most common canine uroliths?
- Struvite and calcium oxalate
Green LO What other types of uroliths besides calcium oxalate and struvite are there?
- Silicates
- Urate
- Cysteine
Green LO Which laboratory workup should be performed in animals with calculi? List 4.
- Abdominal palpation (UTI vs obstruction)
- CBC/Chem/UA
- Urine culture and sensitivity
Green LO How can radiolucent calculi be diagnosed?
- Ultrasound
- Double contrast cystography and/or retrograde urethrography
Green LO What samples are you obtaining intraoperatively for cystotomy for stone removal and for which analysis?
- Stone (culture if not obtained; stone analysis always)
- Bladder wall (for culture if not obtained)
What % of stones get left behind?
20%
Green LO What is the rationale for postop radiographs?
- Want to ensure no stones were left behind
- This helps because reoccurrence is quite common, so you want to protect yourself
Describe the air cystotomy modifications for calculi removal.
- Adequate exposure (50%) - open on midline by identifying the median ligament of the bladder
- Remove all visible stones
- Retrograde flush through the urethra (3 times clean)
- Manipulate the catheter to “feel” for urethral stones
- Postop radiographs
- Follow up exam and urine analysis
Green LO Which 3 stone types cannot be medically dissolved and thus always require surgery?
- Calcium oxalate
- Calcium phosphate
- Silicate stones
Green LO Why may surgery be the treatment of choice also for stone types which are medically dissolvable? List 4 reasons
- Cost
- Need for frequent rechecks
- Possible urethral obstruction in males
- Poor owner compliance with maintaining a suitable dietary regimen
Green LO For male dogs where frequent reoccurrence of uroliths is anticipated, such as in Dalmatians, which surgeries may be advantageous to combine?
- Cystotomy plus scrotal urethrostomy
