Combined Use of Intravesicular Ureteroneocystostomy Techniques to Correct Ureteral Ectopia in a Male Cat

Introduction

Ureteral ectopia, the result of abnormal embryogenesis, is the most common cause of congenital urinary incontinence in the cat.^1–7 Although ectopic ureters are considered uncommon in dogs, they are considered extremely rare in cats, with < 25 feline cases reported in the veterinary literature.^1,2,4,6,8 Several differences in this congenital anomaly exist between cats and dogs. Unlike dogs, where females are 20 times more likely to be affected, an approximately equal sex predisposition in cats has been reported.^2,4,6,8 The observed higher prevalence of this condition in female canines compared with males is likely a result of the increased manifestation of urinary incontinence in the female sex.^4,7 This is a result of female ectopic ureteral termination sites, such as the vagina or vestibule, which tend to occur in locations not controlled by a sphincter mechanism.⁴ Termination sites in male dogs that occur proximal to the external urethral sphincter do not result in urinary incontinence.⁴ The male urethra is also capable of allowing retrograde filling of the bladder as a result of better opposition of distal flow of urine due to its increased length.⁷ Ectopic ureters in cats are most commonly identified as extramural, which again differs from dogs in which the intramural variety predominates.^6,8,9 Finally, cats are reported to have bilateral ureteral ectopia, whereas unilateral ectopia predominates in dogs.⁵

Neoureterostomy, ureteroneocystostomy, and ureteronephrectomy are surgical techniques that have been performed for correction of ectopic ureters in cats depending on the type (intra- versus extramural) and presence of other urinary tract abnormalities.^2,3 Ureteral surgery in cats can be extremely challenging as the diameter of a normal lumen is ∼ 0.4 mm.^10–12 Moreover, the ureteral wall is very muscular, which can lead to spasm after manipulation and a reduction in lumen size.^10–12 Ureteral reimplantation in feline renal transplantation is performed using an operating microscope, which provides 5–22 times magnification, but requires advanced training and familiarity with specialized equipment.¹³ The purpose of this report is to describe the combined use of two intravesicular ureteroneocystostomy techniques for surgical correction of bilateral extramural ectopic ureters in a male cat without the use of an operating microscope. An intravesicular mucosal apposition (modified Leadbetter-Politano) and “drop-in” ureteroneocystostomies were performed on the left and right ureter, respectively.

Case Report

A 2 yr old castrated male Himalayan was referred to the Ontario Veterinary College Health Sciences Centre for further evaluation of urinary incontinence. According to the cat’s owners, urine leakage and frequent licking of the perineal region had been present since birth. A 2 wk trial of phenylpropanolamine (1 mg/kg q 8 hr) 1 mo prior to presentation did not improve clinical signs.

On presentation, the cat was quiet but alert and vital parameters were within normal limits. Severe urine scald and secondary dermatitis were noted around the prepuce, perineum, and caudal aspect of the hind limbs. Abdominal palpation revealed an enlarged left kidney.

Further evaluation of urinary incontinence included blood work, urinalysis, urine bacterial culture and sensitivity, and abdominal ultrasonography. Complete blood cell count and serum biochemical analysis results were unremarkable. Urinalysis of a sample obtained by cystocentesis revealed an appropriate urine specific gravity (1.047) and presence of occasional leukocytes and blood (3+). Urine bacterial culture did not yield any growth.

Abdominal ultrasound revealed marked hydronephrosis of the left kidney and marked left hydroureter (∼ 4 mm in diameter). The left ureter was visualized terminating in the urethra ∼ 2 cm caudal to the neck of the bladder. Examination of the right kidney did not reveal any abnormalities. The right ureter could not be visualized (most likely due to its small size) and furosemide^a (1 mg/kg) was administered IV in an attempt to observe urine jets from its termination into the lower urinary tract. Repeat ultrasonography of the lower urinary tract revealed urine jets from both the left and right ureters entering the urethra and retrograde urine flow into the bladder. A diagnosis of bilateral, extramural ureteral ectopia with associated left hydroureter and left hydronephrosis was tentatively made. Prior to surgical intervention, advanced imaging (either contrast enhanced computed tomography or IV urography) was recommended to definitively characterize the termination of the right ureter, but was declined by the owners.

Surgical options discussed with the owners included ureteroneocystostomy of the left ureter and evaluation of the termination of the right ureter with possible surgical intervention required if it was ectopic. Concerns of an increased complication rate with surgical correction of the right ureter, if required, were related to its likely normal size and the fact that the majority of ureteral surgeries in cats with normal sized ureters (i.e., renal transplantation) are performed with an operating microscope using microsurgical techniques.^10,13

The following day, the cat was routinely anesthetized and an exploratory celiotomy was performed. Bilateral, extramural ectopic ureters were visualized at the time of surgery (Figure 1). A ventral cystotomy was performed and the left ureter was ligated and transected at the site of insertion into the urethra. An intravesicular, mucosal apposition (modified Leadbetter-Politano) ureteroneocystostomy was performed.^10,13 Briefly, a mucosal incision was made in the bladder wall and a curved mosquito hemostat was passed through the serosa. A stay suture (4-0 polydioxanone)^b placed in the left ureter was grasped with the hemostat, and the ureter was drawn into the bladder. The ureter was then spatulated and sutured to the bladder mucosa using five simple interrupted sutures with 6-0 polydioxanone. A 3.5-French (Fr) feeding tube^c was temporarily placed in the ureteral lumen to improve visualization and maintain patency while sutures were placed.

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Despite the potential increased risk of complications associated with surgical reimplantation of the right ureter, right ureteronephrectomy was not performed because left renal function was potentially reduced and urinary incontinence would presumably continue if the right ureter was left in an ectopic location. The right ureter was ligated and transected at its termination on the urethra. A drop-in ureteroneocystostomy was performed.^11,14 Briefly, a mucosal incision was made in the bladder wall and a curved mosquito hemostat was used to pass through the serosa. A stay suture (6-0 polydioxanone) placed in the periureteral tissue of the right ureter was grasped with the a hemostat and the ureter was drawn into the bladder. A strand of suture (2-0 polydioxanone) was temporarily placed within the lumen of the right ureter to maintain patency and one transmural suture (6-0 polydioxanone) from the ureter to the bladder mucosa was placed leaving ∼ 0.5 cm of the distal ureter free within the bladder lumen. Another single suture (6-0 polydioxanone) was placed from the serosal surface of the bladder to the ureter.

The cystotomy was closed in a simple continuous pattern followed by a routine closure of the celiotomy. The cat recovered uneventfully from anesthesia and was monitored in the intensive care unit postoperatively. A transurethral urinary catheter was placed postoperatively to monitor urine output. Systemic analgesia was provided with an IV constant rate infusion of fentanyl^d (2–6 µg/kg/hr) and meloxicam^e (0.1 mg/kg IV q 24 hr).

The following morning, the patient failed to produce an appropriate amount of urine (< 1 mL/kg/hr). Physical examination revealed a distended abdomen and uroabdomen was suspected. Abdominal ultrasonography revealed a large amount of free peritoneal fluid with no identifiable urinary bladder. Abdominocentesis was performed and yielded blood-tinged, straw-colored fluid. Electrolytes were evaluated at that time and potassium was 5.1 mmol/L (3.6–5.2 mmol/L). Uroabdomen was presumed and repeat celiotomy was recommended to evaluate the ureteral reimplantation sites. Serum biochemical analysis was performed prior to surgical re-exploration and azotemia was identified (urea was 17.7 mmol/L; reference range, 6–12 mmol/L and creatinine was 447 μmol/L; reference range, 50–190 μmol/L).

The cat was routinely anesthetized and the previous celiotomy incision was reopened. A marked amount of fluid was found within the peritoneal cavity and samples were collected for bacterial culture and sensitivity analysis. There was no evidence of urine leakage from the previous cystotomy incision. The incision was reopened and the ureteral reimplantation sites were evaluated. The right ureter remained present within the bladder lumen and was catheterized using 2-0 polydioxanone to confirm its patency. Urine was seen emptying into the bladder lumen from the right ureter. Upon evaluation of the left ureteroneocystostomy, a defect was visualized. Retrograde catheterization of the ureter confirmed a 2 mm defect between interrupted sutures, which allowed urine leakage into the peritoneal space. One simple interrupted suture using 5-0 polydioxanone was placed to close the defect from the serosal surface of the bladder. A 3.5-Fr transurethral ureteral catheter was placed in the left ureter. The cystotomy site was closed as before, and prior to routine closure of the celiotomy site, a 7 mm hubless, silicone, flat, closed suction drain^f was placed. The cat recovered from anesthesia without complications and was monitored in the intensive care unit postoperatively.

The following day, the cat was bright and alert, vital parameters were normal, and urine production from the urinary catheter (measured while the cat was receiving half-strength hypotonic IV fluid therapy^g at a maintenance rate of 12 mL/hr) was appropriate. The abdominal drain had minimal production (∼ 0.5 mL/kg/hr) and was removed 48 hr later. The urinary catheter was prematurely removed 48 hr postoperatively by the cat and stranguria was noted. Urethral spasm was suspected and phenoxybenzamine^h (0.7 mg/kg q 12 hr) was initiated to decrease urethral resistance.

Forty-eight hr postoperatively, serum biochemical analysis revealed moderate azotemia (urea was 20.2 mmol/L and creatinine was 506 µmol/L). Urine specific gravity was 1.009. Postrenal azotemia was suspected secondary to previous ureteral obstruction and uroabdomen. The cat remained appetent and was drinking normally. Seventy-two hr postoperatively, serum creatinine was 300 µmol/L and the cat was urinating appropriately in a litter box. Mild urinary incontinence was noted.

The cat was discharged to the care of his owners with amoxicillin trihydrate/clavulanate potassiumⁱ (18 mg/kg [62.5 mg] q 12 hr) for 7 days, and instructions to administer 15 mL/kg of subcutaneous fluids^j q 24 hr until re-evaluation.

The owners returned for re-evaluation with the cat 2 wk postoperatively. The cat was not receiving any medication, and the owners reported frequent but continent urination in the litter box. The previously noted urine scald and secondary dermatitis were markedly improved. Ultrasonographic examination exhibited mild dilation of the right renal pelvis and ureter. The left ureter and renal pelvis remained dilated but had not significantly changed in size since the time of initial ultrasonographic examination. Serum biochemical analysis revealed urea (9.1 mmol/L) and creatinine (180 µmol/L) levels to be within normal limits. Repeat abdominal ultrasonography was recommended in 2 wk (4 wk postoperatively); however, the cat was not returned for re-evaluation. During a telephone conversation 6 mo following surgery, the cat remained continent and was clinically normal.

Discussion

To the authors’ knowledge, this is the first clinical report of the combined use of intravesicular ureteroneocystostomy techniques to correct bilateral extramural ectopic ureters in a male cat. An intravesicular mucosal apposition technique on the left ectopic ureter was chosen, considering its dilation (∼ 4 mm) made the procedure technically easier.^10,13 Left ureteronephrectomy was not contemplated as it was felt that surgical reimplantation of the left ureter would be successful and that renal and ureteral function could be maintained (or improved), considering the hydronephrosis and hydroureter were mild. Although right ureteronephrectomy would have been technically less challenging and associated with fewer complications postoperatively, the study authors chose to perform a drop-in ureteroneocystostomy on the normal-sized right ectopic ureter because left renal function was not assessed preoperatively.^10,11 The drop-in technique was selected because it can be performed on very small ureters, such as the right ureter in the cat described in this case, which was normal in size (∼ 0.5 mm) and does not require the use of an operating microscope.^10,11 Furthermore, leaving the right ureter in an ectopic location to minimize the risk of postoperative complications associated with ureteral reimplantation was not elected because the cat would most likely have remained incontinent.

The drop-in ureteroneocystostomy technique, performed in this case on the right undilated ectopic ureter, was developed for cats undergoing renal transplant as a solution to the technical challenges and complications encountered when performing ureteroneocystostomy procedures described for humans and dogs.^10,11 The drop-in technique does not involve the use of an operating microscope, and it has been shown that a short segment of ureter within the bladder will be covered with bladder epithelium during healing.¹¹ Unfortunately, the drop-in ureteroneocystostomy was associated with ureteral obstruction in 7 of 11 cats undergoing renal transplant when the technique was initially performed.¹¹ The lack of mucosa-to-mucosa apposition resulted in exposure of the periureteral tissues and bladder submucosa to urine potentially leading to inflammation and granuloma formation.^10,13,14 Ureteral obstruction is most commonly detected 2 wk following reimplantation via ultrasonography.¹⁰ The requirement of a second surgery to correct ureteral obstruction in cats that had undergone renal transplant increased morbidity and mortality, hospitalization time, and cost for owners. Another complication with the drop-in ureteroneocystostomy is hemorrhage from the ureteral artery.^10,13,14 The ureteral artery cannot always be ligated at time of reimplantation, and subsequent hematoma formation can occur within the urinary bladder leading to persistent hematuria.¹⁰ Some transplant patients have even required whole blood transfusions.¹⁰ Neither excessive hemorrhage nor hematuria were noted in the patient described in this report.

Kochin et al. (1993) described a microsurgical technique adopted from rats in an attempt to decrease obstructive complications associated with the drop-in ureteroneocystostomy.¹¹ Microsurgical modification did not decrease the incidence of ureteral obstruction.¹¹ In 1996, an intravesicular mucosal apposition technique (modified Leadbetter-Politano) was described for ureteroneocystostomy using microsurgical techniques in cats undergoing renal transplant.¹⁰ That technique was recommended for ureteral reimplantation in cats undergoing renal transplant as ureteral obstruction was not seen in six consecutive cases likely due to the mucosa-to-mucosa apposition at the reimplantation site.¹⁰ Most recently, Mehl et al. (2005) described the use of an extravesicular, simple interrupted, mucosal apposition ureteroneocystostomy technique for ureteral reimplantation in cats.¹³ That technique removes the need for a ventral cystotomy and bladder eversion, which can result in increased edema and postoperative inflammation at the reimplantation site leading to mild-to-moderate ureteral obstruction.¹³ The drawback of the techniques described above for ureteroneocystostomy of a normal-sized feline ureter is the requirement for training and familiarity with microsurgical techniques using an operating microscope.

In the cat described in this report, uroabdomen was diagnosed 24 hr postoperatively. The authors suspected a complication related to the right ureteroneocystostomy given the previously reported high complication rate with the drop-in technique, although it was deemed too early for ureteral obstruction secondary to granuloma formation at the reimplantation site. At that point, left renal function was still uncertain due to the hydronephrosis and the possibility of having to perform right ureteronephrectomy was concerning. Furthermore, as uroabdomen was an acute complication there was likely insufficient time for the right ureter to dilate secondary to obstruction, which would have made an intravesicular mucosal apposition technique for ureteroneocystostomy technically easier.¹³ The second exploratory celiotomy unexpectedly revealed a complication with the left ureteroneocystostomy site. Evaluation of the right ureteroneocystostomy site, where the drop-in technique was performed, revealed a patent ureter and no evidence of urine leakage, but with evidence of ureteral mucosal migration.

As previously discussed, complications related to ureteral reimplantation in cats have commonly been reported. The authors suspect that leaking of urine around the left ureteroneocystostomy was secondary to increased distance either between the simple interrupted sutures or because of an insufficient number of simple interrupted sutures when the ureteroneocystostomy site was created. The left ureteroneocystostomy was performed using a previously published description and the authors suspect that leakage between ureteroneocystostomy sutures might not have occurred if a 3.5-Fr transurethral ureteral catheter had been placed, providing a conduit for urine drainage.¹⁰ Steffey and Brockman (2004) reported the use of a 5-Fr transcystic ureteral catheter following ureteral obstruction after ureteroneocystostomy.⁶ Those authors suggested that this type of catheter was superior to the transurethral ureteral catheter as its size and stiffness prevented expulsion of the ureteral portion of the catheter into the urinary bladder.⁶ Following re-exploration of the cat’s left ureteroneocystostomy site, a single suture was placed in the location of the defect and a transurethral ureteral catheter was placed to maintain bladder decompression and span the ureteroneocystostomy site.

In the cat described in this report, the presence of postoperative azotemia and right renal pelvic and ureteral dilation 2 wk following ureteroneocystostomy were expected findings.^11,13 The postoperative azotemia was likely representative of postrenal azotemia from ureteral obstruction as the patient was well hydrated and was not azotemic preoperatively.¹³ However, a renal component may have concurrently existed from either mild, undetected interstitial nephritis or decompensation of the left hydronephrotic kidney.¹³ Similarly to what has been reported in studies using dogs, reduced renal blood flow and glomerular filtration rate may have contributed to the azotemia observed postoperatively in the cat described in this report.^15,16 Renal pelvic and ureteral dilation is reported following both intra- and extravesicular ureteroneocystostomy techniques and is believed to be secondary to partial obstruction at the reimplantation site.¹³ In a study performed by Mehl et al. (2005), lower serum creatinine levels postoperatively were observed with an extravesicular ureteroneocystostomy technique compared with intravesicular techniques. That finding was likely because the extravesicular technique does not require bladder eversion, which can lead to inflammation at the ureteroneocystostomy site and some degree of ureteral obstruction.¹³ Based on those findings, the authors of that study concluded that an extravesicular approach is the method of choice for reimplantation of undilated feline ureters.¹³

In the cat described in this report, a drop-in technique was performed on the right ectopic ureter, which subjects the periureteral tissues and bladder submucosa to urine, resulting in inflammation and potentially renal pelvic and ureteral dilation, which was present ultrasonographically 2 wk postoperatively.^10,13,14 Based on the improving serum biochemical analysis performed 2 wk postoperatively, the authors suspect that the ureteral obstruction was resolving. The persistence of left-sided dilation of the ureter and renal pelvis identified postoperatively in this cat were also anticipated.^3,13 Following the relief of ureteral obstruction, Mehl et al. (2005) determined that postoperative renal pelvic dilation was slower to resolve compared with the duration of elevated serum creatinine.¹³ Complete postoperative resolution of hydroureter following successful surgical correction of ureteral ectopia may not occur.^3,8 Despite the presence of pronounced hydroureter and hydronephrosis preoperatively, good short- to intermediate-term prognosis has been reported.⁶ Unfortunately, follow-up serum biochemical analysis or ultrasonographic evaluation of the urinary tract could not be performed beyond 2 wk postoperatively to document renal function and normalization in renal pelvic and ureteral dilation; however, the cat remained clinically normal 6 mo following surgery.

Although extravesicular ureteroneocystostomy would have been ideal for ureteral reimplantation in the cat described in this case, the authors do not commonly perform microsurgical techniques with an operating microscope. A drop-in ureteroneocystostomy was performed on the undilated right ectopic ureter without the use of an operating microscope, because an alternative operative maneuver (aside from right ureteronephrectomy) was not present. A successful outcome was achieved in this case despite the high incidence of complications previously reported when the drop-in technique was performed in cats undergoing renal transplant and may be considered for treatment of undilated ectopic ureters when experience with microsurgical instrumentation is not available.^10,11,13,14

Excretory urography, pneumocystography, retrograde vaginography, urethrography, ultrasonography, computed tomography, MRI, cystoscopy, or combinations of those methods have been used to diagnose ureteral ectopia in dogs and cats.^2,7,9 With the use of those techniques, a definitive diagnosis of ectopic ureter, their termination site and concurrent abnormalities of the urinary tract can be made.^2,3 Computed tomography has been reported as a noninvasive technique for diagnosis of ectopic ureters in dogs; however, has yet to be reported for diagnosis of ectopic ureters in cats.¹⁷ The use of advanced imaging in the cat described in this case may have been helpful to definitively diagnose the right ectopic ureter preoperatively and plan for microsurgical ureteroneocystostomy, avoiding the potential complications associated with drop-in ureteroneocystostomy technique.

Conclusion

Bilateral, extramural, ectopic ureters terminating in the urethra distal to the bladder neck were identified in a 2 yr old castrated male Himalayan with a history of urinary incontinence since birth. An intravesicular, mucosal appositional technique was used to transplant the left dilated ureter into the bladder. A drop-in ureteroneocystostomy was performed on the right undilated ureter. The combined use of two different intravesicular ureteroneocystostomy techniques without the use of an operating microscope, avoiding unilateral ureteronephrectomy, was successful in this case. A drop-in ureteroneocystostomy may be considered when performing surgical correction of an undilated extramural ectopic ureter in cats when experience with microsurgical instrumentation is not available. Advanced imaging to definitively diagnose the termination site of both ureters may allow for preoperative planning of microsurgical techniques for ureteroneocystostomy in cats.