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