Feline urinary diversion procedures (Proceedings)


Feline urinary diversion procedures (Proceedings)

Nov 01, 2010

Urine diversion techniques are performed to temporarily or permanently divert urine from its normal anatomic course from the kidney through the ureter to the bladder and finally through the urethra. Veterinarians are most familiar with temporary urine diversion (urethral catheters) that are often used to stabilize animals that are sick as a result of metabolic changes associated with urinary tract obstruction. Temporary diversion (peritoneal drainage) may also be used as a bridge to more definitive surgical procedures such as repair of a ruptured urinary bladder.

Permanent urinary diversion is performed as a surgical procedure to redirect or reconstruct portions of the urinary tract that have been damaged by trauma or neoplastic involvement or for palliation of recurring urethral obstruction. Most permanent procedures performed in animals have been to circumvent areas of the urethra prone to obstruction with calculi or mucus plugs.

Temporary Diversion
      A. Urethral
      1. Useful for maintaining patency of urethra in obstructed animals, measurement of urine production in animals with renal disease, and as stents to allow uroepithelium to migrate over tears or lacerations to the urethra.
      2. Soft rubber or silicone preferable to polypropylene and should be connected to a "closed" urinary system.
      3. We do NOT routinely administer antibiotics to animals with indwelling catheters (selection for hospital/resistant pathogens) BUT we do urine culture and sensitivity when we remove the catheters.
      B. Prepubic urinary diversion
Tube Cystostomy is an easily performed urinary diversion procedure that allows drainage of urine from animals where indwelling urethral catheters cannot be passed. Has also proven useful as a palliative procedure for those animals with neoplastic disease of the bladder/urethra.
      1. Identical procedure to "feeding tube gastrostomy" tube placement but using the bladder.
      2. Place a purse-string suture in the rostral 13/rd of the ventral bladder wall using absorbable suture.
      3. Make a stab incision in the middle of the purse-string and insert a Foley or Pezzar catheter into the bladder (AFTER passing it through the abdominal wall first) and tighten the purse-string.
      4. Place a "pexy" suture both cranially and caudally between the bladder wall and the abdominal wall using absorbable suture.
      5. Connect the catheter to a closed urinary collection system.

Perineal Urethrostomy (PU)
Attempts at PU in the feline were made initially in the 1950's by Carbone. Initial attempts failed because of the lack of recognition that the obstruction occurred in the penile urethra and initial urethrostomy techniques excised only the distal portion of the penile urethra. Over the next 15-20 years, surgery evolved/improved and the classic Wilson-Harrison urethrostomy was described in 1974. Other variations of the technique have been described but the basic principals remain unchanged. MANY PU's were performed in the 1970's and 1980's and continue to be performed today although total numbers have decreased due to dietary management used with Feline Urologic Syndrome (FUS). A report from the U. of Minnesota described the frequency of this disease (FUS) as declining from 40 cases/1000 cats evaluated in the 1980's to 20 cases/1000 cats evaluated in the 1990's. Similarly, the frequency of urethrostomy decreased from 19/1000 cats in the 1980's to 2 casaes/1000 cats in the 1990's. There is some evidence that the prevalence of calcium oxalate stones in cats have increased over the past 10 years probably due to popular acidifying diets.

A. Indications/Rule outs for PU
     • -Repeated obstruction due to FUS/FLUTD
     • -Surgery is economically feasible when one considers the economics of repeated obstruction
     • -Regardless of underlying cause (many have been postulated), obstruction tends to occur in the penile urethra. Various exacerbating causes have been described including stress, low water consumption, diet, obesity, etc. Bacterial infection is RARELY a contributing factor to the disease unless the animal has been previously catheterized thus antibiotic usage does NOT influence the disease process.
     • -Radiographs contrast procedures are indicated to rule out cystic/urethral calculi prior to performing urethrostomy