Urinary System Flashcards
Define: nephrotomy
cut into the kidney
Define: partial nephrectomy
remove part of the kidney
Define: nephroureterectomy
remove the kidney and ureter
Define: pyelolithotomy
remove stones from the renal pelvis
Define: nephrostomy tube
placing a tube into the kidney
Define: lithotripsy
a treatment using US shock waves to break stones/calculi into small particles
What is the arterial and venous supply of the kidney?
Renal artery comes from aorta
Renal vein drains to CdVC
At renal hilus –> split into dorsal and ventral branches –> interlobular branches which DO NOT cross midline
What are the most common nephroliths?
41% Ca oxalate
What clinical signs are associated with nephroliths?
Nonspecific: depression, anorexia, hematuria, pain
Possible uremia and hydronephrosis
How do you diagnose nephroliths?
Survey radiographs / US
What parameters do you use to determine the best management for nephroliths?
- Type of calculi
- Anatomical location
- Clinical effects
o If asymptomatic may just monitor renal function and imaging
o Removal damages kidney (20-50% reduction in function), but improper medical management can make condition worse
When is surgery for nephroliths indicated?
Obstruction
Infection associated with the calculi
What are the four main treatment options for nephroliths?
Medical management
Lithotripsy
Nephrolithotomy
Pyelolithotomy
How do you perform a nephrolithotomy? (10 steps)
- Ventral midline celiotomy
- Retract mesocolon or mesoduodenum
- Dissect retroperitoneal fat to isolate vessels
- Temporarily (20 minutes) occlude blood supply to kidney using rumel tourniquet or bulldog vascular clamp
- Mobilize kidney
- Make a sagittal incision and identify stone
- Remove stone manually
- Submit for analysis and culture renal pelvis
- Flush renal pelvis and ureter with heparinized saline
- Catheterize ureter to ensure patency
What instruments can you use to occlude renal vessels?
Rumel tourniquet (careful not to damage endothelium, high risk of thromboembolism) Bulldog vascular clamp
How long can you occlude the renal vessels for?
20 minutes
How do you close the surgical site in a nephrolithotomy?
Sutureless closure: hold for 5 minutes to form fibrin seal, then suture capsule only
Replace kidney in renal fossa and nephropexy to prevent renal torsion
What are the advantages of a pyelolithotomy over a nephrolithotmy and when would this be indicated?
Preferred if stone is located in renal pelvis and/or there is dilation of the pelvis
Does not require occlusion of blood supply, does not damage nephrons
How is a pyelolithotomy performed?
Longitudinal incision at renal pelvis
Removal of stone
Closure of pelvis
What is the post-operative management of a nephrolithotomy?
- Post-op radiogrpahs – look for additional calculi
- Monitor PCV, central venous pressure (hydration), urine output, and renal enzymes/electrolytes
- Provide diuresis – helps maintain renal perfusion and minimize clot formation
How can you diagnose renal trauma?
o Contrast excretory urography
o Exploratory celiotomy
o Ultrasound
How do you manage renal trauma?
- Minor trauma – conservative treatment
o Bruising or subcapsular hematoma
2. Moderate trauma – surgical intervention o Capsular/parenchymal tears o Extravasated urine/blood o Hemostatic agents/partial nephrectomy o Omental patching
- Major trauma
o Extensive parenchymal or vascular damage can lead to hemorrhagic shock and death
o If parenchyma is shattered consider partial nephrectomy or nephroureterectomy (evaluate contralateral kidney function first)
How is a nephroureterectomy performed?
- Mobilize kidney
- Identify vessels and ligate separately
- Separate and ligate ureter and vesicoureteral junction
What are the (4) indications for performing a nephroureterectomy?
- Severe infection or trauma
- Obstructive calculi with persistent hydronephrosis
- Neoplasia
- Transplant
Why would you perform a partial nephrectomy and what are the disadvantages over a nephroureterectomy?
- Indications: Compromised GFR in contralateral kidney in the face of trauma, focal hemorrhage, neoplasia
- Advantages – preserves renal function
- Disadvantages – higher incidence of post-operative hemorrhage, technically more difficult
How do you perform a partial nephrectomy?
- Occlude blood supply
- Incise and peel back capsule
- Pass suture with straight needle, dividing kidney in thirds
- Tighten sutures to occlude and remove diseased tissue
- Loosen tourniquet
- Close capsule
What is hydronephrosis?
Progressive dilatation of the renal pelvis and atrophy of the renal parenchyma
What are the clinical signs of hydronephrosis?
Unilateral: abdominal distension with palpable mass
Bilateral: severe azotemia and death
How is hydronephrosis diagnosed?
Abdominal rads / excretory urogram / US
How is hydronephrosis treated?
- Eliminate cause
- Evaluate function
5 week obstruction = may regain 25% - Nephroureterectomy for non-functional or severe parenchymal damage
What is the surgical treatment for severe/advanced pyelonephritis?
Nephroureterectomy
How are animals infected with the giant kidney worm?
Fish or frog consumption
What are the clinical signs of giant kidney worm infection, and how is it diagnosed?
Destruction of renal parenchyma –> kidney failure
Often diagnosed on necropsy, may be visualized on US/rads
How is the giant kidney worm treated surgically?
Nephrectomy or nephrotomy depending on severity of infection
What are the most common benign and malignant renal tumors in the dog and cat?
Benign: renal adenoma (both)
Malignant: renal carcinoma (canine), renal lymphoma (feline)
How are renal carcinomas managed?
Nephroureterectomy and chemo
How is renal lymphoma managed?
Medically or surgically (nephroureterectomy) depending on staging
Describe the development, signalment, and prognosis of nephroblastomas
Congenital neoplasia that occurs as part of the developing kidney.
Affects young dogs and cats.
MST 6 months
What are 4 indications for renal biopsy?
Suspected neoplasia
Nephrotic syndrome
Renal cortex disease
Non-diagnosed ARF (*not indicated in CRF b/c will not change prognosis)
What are the techniques available for renal biopsy?
o Percutaneous (small dogs and cats): secure kidney against abdominal wall – blind technique o US guided (preferred method): advance needle into prepared area penetrate capsule can identify target lesions o Keyhole: modified surgical flank approach secure kidney to incision introduce biopsy needle o Laparoscopic-assisted: forceps hold kidney skin incision needle placement through incision o Wedge or incisional: ventral midline celiotomy occlude renal vessels crescent shaped sample (5-10mm long, 5mm deep in cortex) close with mattress suture
What are the risks and contraindications to renal biopsy?
o Severe hemorrhage (d/t hypertension, NSAID within 5 days, coagulopathy, poor technique), hematuria (usually resolves 2-3 days), hydronephrosis (ureteral obstruction from clot)
o Contraindicated in coagulopathies (obtain clotting profiles), hypertension (risk of hemorrhage), severe chronic hydronephrosis (just do nephroureterectomy)
What are the indications of a renal transplant?
• irreversible acute renal failure, decompensated chronic renal failure, polycystic disease
What are the screening parameters for renal transplant?
CBC, chemistry (renal function – may require diuresis to get to acceptable level), U/A and culture, abdominal radiographs / US / echo, FeLV/FIV/Toxo screens
What are the considerations when selecting renal transplant?
• cost, frequent visits, immunosuppression (lifelong drug suppression)
What is the prognosis for renal transplant patients?
MST ~2 years, but 23% do not survive to discharge
Define: neoureterocystotomy
making a new ureteral opening into the bladder
Define: neoureterostomy
transplantation of ureter into another place
Define: nephroureterectomy
removal of ureter and kidney
Define: ureterotomy
incision into ureter (and subsequent closure)
Defin: ureteroureterostomy
transplantation of one ureter into another ureter/into itself
What is an ectopic ureter?
Failure of one or both ureters to terminate in the normal location (level of trigone)
What is the breed, sex, age and clinical signs of ectopic ureter?
- Breeds: Siberian Husky, Lab/Golden, West Highland Terrier
- Sex: female canines (rare in cats)
- Age: young
- CS: incontinence, failure to house train, UTI, urine scalding
How do you diagnose and classify ectopic ureter and what is the most common type?
• Dx: Primarily excretory urography +/- pneumocystography and fluoroscopy
o Alternatively: image enhanced CT, ultrasound, and cystoscopy (visualization of abnormal uretal orifice)
• Extramural classification (less common) – enters and exists in abnormal location (into neck, urethra, or vagina)
• Intramural classification (most common) – enters normally but exits abnormally
How do you treat ectopic ureter?
- Neouretrocystostomy
♣ End to side – reimplantation of ureter for extramural EU (not as common)
• Cystostomy incision ligation and transection of ureter where it enters urethra stab incision into bladder transplantation into normal location spatulate (open up ureteral entrance) and suture
♣ Side to side – intravesicular diversion for intramural EU
• Cystostomy incision identify ureter slit incision at normal location suture mucosa to mucosa catheterize and ligate remove catheter and tighten sutures dissect out ureteral remnant - Laser transection of wall between EU and bladder or urethra
♣ Scope placed into urethra/bladder identify abnormality obliterate wall underlying ureter until urine allowed to flow normally
♣ Cannot remove remnant ureter that may contribute to incontinence
What is the prognosis after treatment of ectopic ureters?
Incontinence improves in 60%, 90% improvement when phenylpropanolamine (PPA) added
What is a ureterocele?
persistent membrane in embryonic development and dilation of distal ureter
What are the two types of ureteroceles?
Intravesicular (normal) or ectopic (neck/urethera)
What are the clinical signs associated with ureteroceles?
UTI, incontinence, azotemia if obstructed
How are ureteroceles diagnosed?
IV urography with contrast media
How are ureteroceles treated?
Intravesicular –> uretrocelectomy (removal of persistent membrane only)
Ectopic –> neoureterocystotomy with uretocelectomy
What is the #1 cause of ureteral trauma?
Iatrogenic
How is ureteral trauma diagnosed?
uroretroperitoneum/uroabdomen visualized with radiographs and/or IV urography
What are the criteria to determine treatment of ureteral trauma?
Time, location, severity
What are the treatment options for ureteral trauma?
- ureteroureterostomy (uretral anastomosis) - procedure of choice for proximal ureter damage
- neoureterocystotomy (ureteral reimplantation)
What two methods are available for urinary diversion after ureteral surgery?
Ureteral stent
Nephrostomy tube
What procedures can be used if you have loss of length of the distal or proximal ureter in the case of ureteral trauma?
- Transureteroureterostomy – used when proximal ureteral length is insufficient to reach the bladder but long enough to cross midline
o Bring ureteral segment across midline and anastomosis to other ureter - Renal descensus
o Mobilize kidney and suture caudally to lumbar musculature - Nephrocystopexy
o Suturing kidney to the cranial edge of the bladder - Psoas hitch
o Fixes the bladder in a more cranial position - Bladder wall flap – used with significant loss of distal ureter
o Elevate bladder flap implant ureter to end of flap suture flap in a tube and close defect
o Significantly decreases bladder volume
What is the most common indication for ureteral surgery?
Ureterolithiasis
What are the clinical signs of ureterolithiasis?
usually asymptomatic unless complete obstruction (UTI, hematuria, anorexia, lethargy, pain)
How is ureterolithiasis diagnosed?
plain radiographs (CaOx and struvites)
What are the indications for surgical treatment of ureterolithiasis?
o Complete obstruction
o Azotemia
o Pyelonephritis
o After 2 weeks of unsuccessful medical treatment
What are the presurgical considerations for ureterolithiasis?
o Cannot predict how long ureter obstructed (cannot predict how well kidney will recover)
o Most cats have preexisting interstitial nephritis unrelated to obstruction
o If azotemic with unilateral obstruction has bilateral renal disease
o High complication rate with surgery
What are the surgical treatment options for ureterolithiasis?
- Cystotomy and retrograde flushing and removal via pyelithotomy
- Ureterotomy (if stone cannot be moved)
♣ Longitudinal incison lavage ureter transverse or longitudinal closure nephrostomy drainage
What are the advantages and disadvantages of ureteral stenting?
- Advantages – decreased morbidity, shorter hospitalization, less complications
- Disadvantages – specialized equipment, steep learning curve
What are the indications for ureteral stenting?
stones, tumor, stricture, blood clot
What is the non-surgical technique for ureteral stenting?
Endoscopic:
ureteral orifice visualized by endoscope guide wire and catheter placed into ureteral orifice identify ureteral pelvis ureteral stent placed, aided by pusher catheter
♣ Requires patient >8kg
What are the surgical techniques for ureteral stenting?
Dogs: cystotomy incision similar guide wire procedure (no pusher catheter required)
Cats, usually placed antegrade through renal parenchyma
How is Subcutaneous Ureteral Bypass (SUB) performed?
Kidney mobilized large-gauge catheter placed into renal pelvis cuff sutured into kidney similar catheter placed in bladder flush every 3-6 months
Flow is from the kidney through shunting port into bladder (bypassing ureter)
Define: cystotomy
cutting into the bladder
Define: cystectomy
cutting a piece of the bladder wall out
Define: cystostomy
surgical creation of an opening into the bladder
Define: cystopexy
attachment of the bladder to the abdominal wall
Describe the anatomy of the bladder, the nerve supply and vascular supply
- Attached by ventral ligament (cut during cystotomy) and lateral ligaments (contain distal ureters, avoid during surgery)
- Trigone = region between urethral and ureteral openings
- Nerve supply: hypogastric n (sympathetic) and pelvic n (parasympathetic)
- Blood supply: caudal vesicular and prostatic/vaginal arteries
What is the urachus and why is it important?
embryonic conduit providing communication between bladder and allantoic sac, problematic if it does not atrophy normally at birth
What are the 4 types of urachal abnormalities? Which is the most common?
- Persistent urachus (patent urachal canal) - most common
- Vesicouracheal diverticulum (external opening is closed, but bladder attachment is patent)
- Urachal cyst (secreting urachal epithelium persists, usually in an isolated segment)
- Urachal sinus (persistent distal urachas remains open)
What are the clinical signs, diagnosis, and treatment of a persistent urachas?
CS: urine dribbling from umbilicus, omphalitis (inflammation of umbilicus), ventral abdominal dermatitis, UTIs
Dx: place contrast in umbilicus
Tx: surgical removal of urachal tube
What are the clinical signs, diagnosis, and treatment of a vesicouracheal diverticulum?
CS: predisposes to uroliths and UTIs
Dx: positive contrast cystography
Tx: partial cystectomy and diverticulectomy
What are the clinical signs and treatment of a urachal cyst?
CS: usually asymptomatic
Tx: surgical excision if CS develop
What are the clinical signs and treatment of a urachal sinus?
CS: omphalitis
Tx: surgical excision
What are some causes of bladder rupture?
Trauma, severe cystitis, neoplasia, urethral obstruction, iatrogenic (cystocentesis, catheterization, manual expression, dehiscence after surgery)
*In any trauma case consider bladder rupture until R/O
T/F: bladder rupture can be ruled out by palpation of the bladder, normal urination, or urine retrieval by catheter
FALSE
What is the progression of clinical signs associated with bladder rupture, and how can it be diagnosed?
Acute CS: (may be asymptomatic), hematuria/anuria, abdominal pain
Progression of signs: dehydration, acidosis, azotemia, hyperkalemia, death in 47-90 hours
Diagnosis:
- Rads - free abdominal fluid, absence of bladder, decreased serosal detail
- US - free fluid, concurrent injuries, helps determine source of injury
- Positive contrast urethrocystogram (most reliable) - leakage of contrast material in abdomen, highlights intestinal loops
- Abdominocentesis - creatinine and potassium in peritoneal fluid > serum creatinine + potassium
How is bladder rupture treated?
Surgical repair immediately if stable (fluids and abdominocentesis to stabilize)
Urinary diversion: urethral catheter/tube cystostomy to help minimize urine accumulation
Exploratory laparotomy: debride tear and necrotic tissue –> close bladder wall –> omentalize/serosal patching catheterize urethra to prevent complete distension
What are the indications for a tube cystostomy?
Any need for urinary diversion
Examples: stabilization of patients with LUT obstruction, bladder/urethral trauma or surgery, neurologic bladders
How is a tube cystostomy performed?
Ventral midline incision
Stab incision into bladder
Insertion of 6-16 Foley/mushroom tip catheter
Purse-string attachment of catheter through abdominal wall
Cystopexy
What are the complications associated with a tube cystotomy?
Inadvertent tube removal Breakage of mushroom tip Fistula formation after removal Urine leakage around tube Hematuria
What are the indications for a cystopexy (3)?
Tube cystotomy
Perineal hernia
Urinary incontinence associated with pelvic bladder
How is a cystopexy performed?
Cranial traction of bladder
Attach bladder wall to abdominal wall with two lines of sutures
What are the two most common types of cystic calculi?
Struvite and Ca Oxalate
What are the clinical signs associated with cystic calculi?
Palpation of large thickened bladder, UTI
How are cystic calculi diagnosed?
Plain radiographs can confirm >90% of cases
Cysteine and urates are radiolucent - pneumocystography, double-contrast cystography, or US
What are the 4 non-surgical treatment options for cystic calculi, and what are the considerations with each?
- Voiding hydropulsion: patient must be small and stones must be smaller than urethral diameter
o Under anesthesia, distend bladder with saline, hold patient upright, express bladder - Transurethral cystoscopy: scope inserted into urethra graspers on scope remove stones
o Stones must be small, urethra must be able to accept scope, not useful for many stones, expensive equipment - Dietary modification: struvites only
o Incorrect diet can worsen condition, cannot be obstructed, wall take a long time - Electrohydraulic lithotripsy: passage of cystoscope, electrode wire and spark generator breaks stones
o Expensive, not readily available, risk of obstruction if not broken down enough
When is surgery indicated for cystic calculi?
Obstruction
No medical options
Other retrieval methods failed
Describe the procedure for removal of cystic calculi from approach to closure including appropriate suture options, patterns, and closure techniques
Ventral approach to bladder is preferred d/t increased exposure of bladder neck and visualization of ureteral orifices
In males, drape prepuce and scrotum in field
- Caudal ventral midline approach
- Isolate bladder and use stay sutures (2 lateral, 1 apex) for manipulation
- Place moistened lap sponges around bladder
- Empty bladder using compression or small needle+syringe
- Stab incision at apex (choose avascular area) and extend incision with scissors (long enough for thorough evaluation) 6. Evert walls for full inspection and remove calculi with instrument
- Pass urethral catheter and flush to ensure patency
- Submit urine stones and mucosal tissue for C/S
Closure should be water tight, sutures should not penetrate lumen, ureters should not be impinged, submucosa (layer of strength) MUST be engaged, serosa-to-serosa contact is desired (encourages fibrin seal)
o 3-0 PDS (monofilament absorbable) is usually preferred, but many sutures acceptable
o Suture patterns:
♣ 1. One or two layer inverting pattern (Cushing Lembert)
• Ensures water-tight closure, not ideal if edematous or if loss of mucosa (makes smaller)
♣ 2. Simple continuous in submucosa Cushing
♣ 3. One or two layer appositional pattern (simple cont. in submucosa simple cont. in seromuscular)
After closure, leak test bladder post op radiographs
What is polypoid cystitis?
Non-neoplastic growth of polyps in the bladder mucosa
Resembles TCC
How is polypoid cystitis diagnosed?
US or cystoscope is presumptive
Biopsy confirms
How is polypoid cystitis treated? What is the prognosis?
Simple resection
Good prognosis
What is the most common bladder tumor and most common urinary tract tumor in both the dog and cat?
Dog: TCC most common bladder and UT tumor
Cat: TCC most common bladder tumor, renal lymphoma most comon UT tumor
How does TCC differ in the dog vs. cat?
Dogs: trigone area
Cats: apex
What is the typical signalment of TCC in both the dog and cat?
What are some predisposing factors?
Dog: older females, Scottish terriers
Cats: middle-aged males
Predisposed by obesity, insecticide exposure, herbicides, cyclophosphamide
What are the clinical signs and physical exam findings in TCC?
CS: straining, hematuria
PE: palpable abdominal mass, painful abdomen, weight loss
Signs of metastatic disease (lungs/bones): sublumbar lymphadenopathy, coughing/dyspnea, lameness
How is TCC diagnosed?
- Avoid FNA!
1. Urine cytology – 30% of tumors will exfoliate cells
2. Cystoscopy – very diagnostic, can visualize and biopsy mass
3. Plain rads – visualize sublumbar lymphadenopathy / bone metastasis, but neoplasia itself difficult to see
4. Positive contrast cystography – filling defect and mass-like effect in bladder
5. US – very sensitive, determines degree of bladder invasiveness, evaluates abdomen for mets/LN involvement
6. Transurethral biopsy via rectum
What is the Bladder Tumor Antigen Test?
What are its advantages and disadvantages?
Latex agglutination dipstick test for TCC
Best used as a routine screening test for older patients
High incidence of false positives d/t hematuria, proteinuria, or infection
How is TCC treated and what are the considerations of treatment?
Chemotherapy (piroxicam, cisplatin, mitoxantrone) +/- surgery
MST 4-6 months, surgery does not extend MST but may give chemo more time work
Partial cystectomy with >1cm borders (rarely able to get all of tumor)
If tumor involves trigone may require salvage procedures to continue successful urination (uretocolonic / ureterouterine anastomosis)
What is hypospadias and how is it managed?
Underdevelopment of the penile urethra (most common developmental abnormality of male genitalia)
o Urethral orifice can occur anywhere along the penis
o Boston terriers predisposed
o Often asymptomatic
If symptomatic, reconstruction procedure
What is urethral prolapse, what are the predisposing causes, and what are the clinical signs?
Protrusion of urethral mucosa through orifice
Predisposition: o Young male brachycephalic dogs o Etiology (unknown) – sexual excitement, dyspnea, infection
Clinical signs: bleeding from prepuce, licking, red-purple mass
What are the criteria for treatment of urethral prolapse?
Asymptomatic: reduce with aid of large catheter, place purse string suture, leave for 5 days
Symptomatic (excessive bleeding, ulcerated mucosa, necrosis, or failure of conservative management): more aggressive treatment
What are the surgical treatment options for urethral prolapse?
- Urethropexy:
Resect urethral mucosa
Place groove director into urethra
Plase 3 full thickness sutures through penile wall and urethra - Resection and anastomosis:
Place catheter
Penile tourniquet to keep penis extruded and control bleeding
180 degree incision to prevent mucosal retraction
Suture and complete resection
What are adjunct treatments to consider with urethral prolapse?
Castration
Surgical correction of airway to decrease straining in brachycephalic breeds
What causes urethral obstruction in dogs and cats and where is obstruction most common?
Cats: mucus plugs (most common – distal 1/3 of urethra), crystals/stones, neoplasia, strictions
Dogs: calculi – ischial arch or just caudal to os-penis
How do you diagnose urethral obstruction, and what are the goals of treatment?
CS: straining to urinate, may be anuric, large palpable bladder
Dx: plain radiographs (radiopaque calculi, large distended bladder), US, contrast urethrogrpahy
Goals: preserve renal function, treat UTI, prevent recurrence
o Give fluids for azotemia!
How do you temporarily relieve urethral obstruction in a dog or cat due to calculi?
- Catheter placement – FELINE
o Plug generally at the very end of urethra –> catheterize with Tomcat catheter/slippery sam + saline - Hydropropulsion (retrograde) – CANINE
o Palpate stone (rectal) –> compress urethra –> pass large-bore catheter to level of obstruction –> pinch off terminal urethral orifice –> inject saline to distend distal urethra, pushing it back into bladder
3.Cystocentesis
Define: urethrotomy
removal of stone directly from urethra
What are the indications for urethrotomy in a dog?
Calculi where hydropropulsion unsuccessful
What is the preferred location for canine urethrotomy and how is a urethrotomy performed? What are the methods available for closure?
Prescrotal urethrotomy preferred
Drape wide (abdomen, prepuce, scrotum)
Urethral catheter to the level of obstruction
Ventral midline incision between base of scrotum and caudal penis
Retract retractor penis muscle
Incise urethra
Remove calculi and flush urethra
Closure methods:
o 4/0 or 5/0 monofilament absorbable
o Second intention healing (leave catheter in and allow to heal over catheter) – less risk of stricture, may face profuse hemorrhage, must hospitalize until hemorrhage ceases
Why is perineal urethrotomy and urethrostomy a less preferred procedure in the dog?
When might it be indicated?
Avoided due to difficulty of procedure (urethra deeper than in prescrotal urethrotomy) and increased risk of infection
Indicated for calculi lodged between scrotum and ischial arch
Procedure:
Anal purse string, urethral catheter
Midline incision between scrotum and anus
Separate bulbospongiosum and incise corpus spongiosum
Urethrostomy
What is a urethrostomy? When is it indicated?
Surgical formation of a permanent opening of the urethra at a new site
Indications:
Permanent damage to the distal urethra
Recurrent urethral obstruction
Obstruction that cannot be retropulsed or removed by urethrotomy
What are the preferred locations for urethrostomy in a dog and cat and why?
Dogs: scrotal - preferred because urethral is more superficial and relatively wide
Cats: perineal or antepubic
In a scrotal urethrostomy, what structures should be draped in your surgical field?
Abdomen, scrotum, and prepuce
In a scrotal urethrostomy, how long should the urethral incision be?
2.5-4cm
5-8x urethral diameter
In a scrotal urethrostomy, what is the most appropriate suturing method?
4/0 or 5/0 absorbable monofilament suture
Ensure to accurately appose skin and mucosa
What are the complications with a scrotal urethrostomy?
Urine leakage into SQ tissue if skin and mucosa are not apposed at closure
Hemorrhage, dehiscence, urine scald, stricture, UTI
What is a disadvantage of a canine prescrotal urethrostomy?
Higher incidence of urine scald
When is a perineal urethrostomy in a cat indicated and what are the goals of the procedure?
A salvage procedure to treat FLUTDS and calculi in male cats
Indicated with frequent obstructions, strictures, or trauma
o Note: increases incidence of bacterial cystitis and does not prevent FLUTDS
Goals of sx:
- Adequate mobilization of urethra
- Preserve urethral branches of the internal pudendal nerve with minimal dorsal dissection
- Creation of a wide urethral orifice
What gland/area of the urethra do you dissect to when performing a perineal urethrostomy in a cat and how can you check the urethral orifice is wide enough?
Dissect to BBU gland
Ensure adequate width with mosquito hemostat to hinge
What are the complications of a perineal urethrostomy in a cat and how can you minimize the complications?
- Hemorrhage (usually resolves over time)
- UTI (common due to anatomical alterations of defense mechanism)
- Stricture (d/t improper surgical technique, may be revised with 2nd procedure and may require antepubic urethrostomy)
- SQ urine leakage (d/t improper suturing or urethral tear)
Treat with indwelling 8 French catheter 5-7 days - Perineal hernia (rare)
- Urinary incontinence (rare) – dorsal dissection causing disruption of pudendal nerves
- Urethrorectal fistula (poor surgical technique)
When is an antepubic urethrostomy indicated, where is it performed in female/male dogs/cats, and what are the complications?
Creation of a urethrostomy on the ventral body wall cranial to the pubis
• Indicated with recurrent pelvic urethral obstruction or failed perineal urethrostomy that cannot be revised
Complications: urine scalding, UTI, incontinence
Performed ventral midline in female dogs and all cats / Parapreputial in male dogs
What are the clinical signs of urethral trauma, how do you diagnose it, and how do you manage it?
CS: hematuria, stranguria, SQ or abdominal fluid accumulation, signs of azotemia
Dx: positive contrast urethrogram (plain rads are not diagnostic)
Incomplete or small lacerations will heal with urinary diversion or uretheral catheter/cystotomy tube
o Duration of catheterization is dependent on severity – minimum 3 weeks
o Catheterization increases stricture formation
Complete rupture requires anastomosis or repair with urinary diversion
What are the causes of urethral strictures, when do patients show clinical signs, how do you diagnose it, and how do you treat it?
Etiology (usually traumatic): urethral sx, trauma by uroliths, iatrogenic (catheterization), healing after minor trauma
> 60% narrowing before CS
Dx: urethrogram or cystoscopy
Treat if CS: urethral dilators, balloon dilation, resection and anastomosis, proximal urethrostomy
