Materials and Methods

Case selection—Female dogs that underwent cystoscopic-guided transection of the membrane separating unilateral or bilateral ectopic ureters from the urethra and bladder at the University of Georgia Veterinary Teaching Hospital or at VCA Veterinary Referral Associates in Gaithersburg, Md, by 1 of 2 board-certified surgeons (MGR or CAR) between May 2005 and May 2008 were eligible for inclusion in the study. Data retrieved from medical records of dogs included in the study consisted of age, weight, preoperative laboratory data (CBC, biochemical profile, and urinalysis, if performed), results of cystoscopic examination, details of the surgical procedure, laser settings and duration, and duration of anesthesia and surgery.

Cystoscopic-guided transection—Patient-specific protocols developed on the basis of results of preoperative evaluations were used for induction of anesthesia. In all dogs, anesthesia was maintained with isoflurane in oxygen. Antimicrobials were administered perioperatively, unless dogs were already being treated with antimicrobials because of urinary tract infection identified prior to cystoscopy. Following induction of anesthesia, dogs were positioned in dorsal recumbency for retrograde cystoscopy and vaginoscopy. The lower urinary tract was examined with a 1.9-, 2.7-, or 4.0-mm rigid cystoscope with passive flow of saline (0.9% NaCl) solution through the endoscope. Both ureteral orifices were identified, and the reproductive and urinary tracts were evaluated for the presence of other abnormalities. Ureter size was evaluated subjectively, and any ureter that was at least twice the expected diameter was classified as hydroureter. Cystoscopic-guided transection of tissue separating the ectopic segment of the ureter from the urethra and bladder was performed with a diode laser or radiofrequency surgical device. The diode laser tip (400 to 800 μm in diameter) was blackened, and the tissue separating the ectopic segment of the ureter from the urethra and bladder was incised, with a laser setting of 12 to 20 W applied in a continuous manner. To blacken the laser tip, the fiber was placed in contact with a sterile wooden tongue depressor. The laser tip was blackened to reduce the risk of noncontact laser injury and to concentrate laser energy at the fiber-tissue interface during the transection procedure. Alternatively, a polypropylene catheter (3.5 or 5F) or guide wire was used to identify the ureteral lumen and to protect the dorsal and lateral walls of the ureter during laser use. The cystoscope was directed medially to maintain contact between the laser tip and the medial wall of the ureter to prevent accidental incision of the lateral ureteral wall. The tissue was incised beginning at the ureteral orifice distally and extending cranially into the bladder lumen (Figures 1 and 2).

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Cystoscopic appearance of the urethra in a 2-year-old spayed female Siberian Husky with urinary incontinence. A—Bilateral intramural ectopic ureters were present with the dilated right ectopic ureter entering the urethra just inside the vestibulourethral junction and the left entering just caudal to the vesicourethral junction. In this image, the right ectopic ureter is below the urethra and the left ectopic ureter cannot be seen. B—The membrane between the urethra and ectopic ureter is being incised with a diode laser, with laser energy delivered through a glass fiber. Owing to the size of the hydroureter, a guide was not used. C—Appearance following completion of cystoscopic-guided laser transection of tissue between the intramural portion of the right ectopic ureter and the urethra and bladder. Notice that the ureteral stoma is now positioned within the bladder. The larger opening is the bladder outflow tract and the lower opening is the right ureter. D—Cystoscopic appearance followed transection of a band at the vestibulovaginal junction. The urethral opening is above and the vagina is below.

Citation: Journal of the American Veterinary Medical Association 237, 2; 10.2460/javma.237.2.191

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Cystoscopic appearance of the urethra in a 1-year-old female English Bulldog with a history of urinary incontinence. The dog is positioned in dorsal recumbency. A—Bilateral ectopic ureters were present, with the right and left ureteral openings (RtEU and LtEU) located in the cranial 3 cm of the vesicourethral junction. The entrance of the urethra into the bladder (US) had a fibrous stricture, preventing passage of a 2.7-mm cystoscope into the bladder. B—Cystoscopic appearance during transection of the tissue between the intramural portion of the right ectopic ureter and the urethra and bladder with a diode laser. A metal guide wire was used to define the lumen of the ectopic ureter during transection.

Citation: Journal of the American Veterinary Medical Association 237, 2; 10.2460/javma.237.2.191

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Patients were allowed to recover from anesthesia in the intensive care unit and were given fluids IV (60 mL/kg/d [27 mL/lb/d]). Postoperative pain was managed according to individual patient needs. All patients were provided with postoperative analgesia, with most patients receiving an opioid, an NSAID, or both.

Follow-up—Success of the surgical procedure was determined by use of telephone interviews conducted after patient discharge from the hospital. A standard questionnaire^a was used for all interviews. Clients were asked questions related to patient health and degree of continence. Outcome of the surgical procedure was graded by the client on a scale from 1 to 5, where a score of 1 was defined as complete resolution of urinary incontinence without any medication; a score of 2 was defined as resolution of urinary incontinence in a dog receiving PPA; a score of 3 was defined as substantial improvement in urinary continence (ie, only 1 or 2 episodes of urine leakage each week); a score of 4 was defined as slight improvement in urinary continence (ie, a decrease in the volume or frequency of urine leakage); and a score of 5 was defined as no improvement in urinary continence. For purposes of the present study, dogs assigned a grade of 1 or 2 were considered to have had a successful outcome.

Results

Sixteen female dogs were included in the study. Median age at the time of surgery was 10.5 months (range, 3 months to 10 years). Client telephone interviews were conducted 1 to 36 months (median, 10.5 months) after patient discharge.

Cystoscopic-guided transection was achieved by use of a diode laser in 15 patients and by use of a radiofrequency surgical device in 1 patient. Contrast cystourethrography with iohexol mixed with saline solution (50:50 ratio) was attempted in 1 dog, and the ureteral path was documented in the operating theater immediately before laser treatment in this dog. Two dogs received submucosal collagen injections immediately following laser division because of an excessively large urethral diameter.

In 9 dogs, urinary tract infection was diagnosed prior to cystoscopic-guided transection of ectopic ureters. Four of these dogs were receiving antimicrobials prior to cystoscopy; the remaining 5 dogs were treated with antimicrobials during and after surgery. Five patients each received hydromorphone (0.05 to 0.1 mg/kg [0.023 to 0.045 mg/lb], IV, q 4 h) or buprenorphine (0.005 to 0.01 mg/kg [0.0023 to 0.0045 mg/lb], IV, q 4 to 6 h) in the immediate postoperative period. Three patients received carprofen (2.2 mg/kg [1 mg/lb], SC, once) during anesthetic recovery. Six patients received deracoxib (2.2 mg/kg, PO, q 24 h) and 3 received carprofen (2.2 mg/kg, PO, q 12 h) for 3 to 8 days after surgery. Six patients received codeine (1 mg/kg [0.45 mg/lb], PO, q 6 h) for 7 to 8 days after surgery.

Outcome was not assessed in the 2 dogs that received submucosal collagen injections immediately following cystoscopic-guided transaction or in 1 dog that subsequently underwent unilateral nephrectomy because of hydronephrosis. Outcome was graded by the owners as 1 (resolution of urinary incontinence without medication) in 4 dogs, as 2 (resolution of urinary incontinence while receiving PPA) in 5 dogs, as 3 (substantial improvement in urinary continence) in 3 dogs, and as 4 (slight improvement in urinary continence) in 1 dog.

Ureteral ectopia was unilateral in 3 patients and bilateral in 13. All ectopic ureteral openings were located in the urethra. Thirteen dogs had additional urogenital anomalies, including bilateral hydroureter (n = 6), unilateral hydroureter (6), a persistent band at the vestibulovaginal junction (6), and a stricture at the vesicourethral junction (1; some dogs had > 1 abnormality).

Total procedure time (including submucosal collagen injections, if performed) was recorded for 11 patients and ranged from 15 to 120 minutes (median, 50 minutes). The first 6 procedures for which total procedure time was recorded had a median duration of 64 minutes (range, 40 to 120 minutes). For the final 5 procedures, median total procedure time was 30 minutes (range, 15 to 79 minutes). Total duration of laser use was recorded in 9 patients and ranged from 18 to 210 seconds (median, 96 seconds).

Complete transection of the membrane separating the ectopic portion of the ureter from the urethra and bladder was accomplished in all but 4 patients. All 4 dogs in which complete transection was not possible had bilateral ureteral ectopia, and one of the ureters in each dog was not fully transected because of difficulties in evaluating the ureteral orifice or the course of the ureter. In one of these patients, cystoscopy was repeated 3 months later and laser transection of the previously untreated ureter was successfully performed. After transection of the second ureter, this patient was assigned an outcome grade of 2. Of the remaining 3 patients in which ablation of only 1 ureter was accomplished, 2 were assigned an outcome grade of 1 and the other was assigned a grade of 2.

Discussion

Results of the present study suggested that cystoscopic-guided transection may be an acceptable alternative to traditional surgical correction of ectopic ureter in dogs. The proportion of dogs with a successful outcome in the present study was similar to proportions reported in previous studies^{1,2,4,10,11,12} involving dogs undergoing surgical correction. In addition, most complications associated with the cystoscopic procedure in the present study were minor and easily managed. Characteristics of the patient population in the present study were similar to those in previous reports^1,5,13 describing the diagnosis and treatment of ectopic ureters.

In the present study, 4 dogs had complete resolution of urinary incontinence with cystoscopic-guided transection alone, but an additional 5 dogs had complete resolution with a combination of cystoscopic-guided transection and PPA administration. This was similar to findings reported when ureteroneocystostomy or neoureterostomy was performed.^2,13 Although 9 of 13 dogs in the present study for which outcome could be assessed had persistent postoperative incontinence, this was also similar to findings in studies^1,2,4,10,11 in which ureteral ectopia was corrected with traditional surgical methods.

A recent study⁸ examining the use of cystoscopic-guided laser ablation of ectopic ureters in male dogs reported that all dogs were continent following surgery. It is difficult to compare the outcome of this procedure in male and female dogs because of the longer external urethral sphincter in male dogs. Further studies evaluating larger numbers of male patients would provide greater insight into the relationship between urethral sphincter length and outcome following correction of ureteral ectopia.

Previous authors have suggested that patients with normal ureteral diameters could be expected to have a better outcome following traditional surgical correction than patients with hydroureter; however, that did not appear to be the case in the present study. Although imaging of the urinary tract following correction of ectopic ureters is not routinely reported in the literature, some studies^2,8 report improvement or reversal of hydroureter following surgical correction. On the other hand, there have also been reports^2,3 of hydroureter developing or worsening following surgery. We believe that in female dogs undergoing correction of ureteral ectopia, the degree of postoperative continence is most strongly associated with the degree of competence of the urethral sphincter. However, all ectopic openings were within the urethra in the patients in the present study. Therefore, we could not determine whether location of the ectopic orifice was associated with outcome.

Laparotomy and ventral cystotomy to allow direct visualization of the trigone, bladder neck, and urethra have long been considered the gold standard for the diagnosis of ectopic ureters in dogs.^6,12 Recently, however, the use of cystoscopy for diagnosis and characterization of ectopic ureters has gained popularity because it allows direct visualization of the lower urinary tract and localization of the ectopic ureteral orifice.^6,7 A previous study¹² of 25 dogs found agreement between cystoscopic and surgical findings in all patients. Whereas the results of treatment in the patients in the present report were similar to results of previous studies^1,2,14 in which traditional surgical correction of intramural ectopic ureters was performed, we believe that cystoscopy provides multiple benefits over more-invasive surgical procedures and avoids risks associated with open abdominal surgery. On the other hand, there are certain risks associated with cystoscopic-guided laser transection, including ureteral or urethral tearing resulting in uroretroperitoneum or uroabdomen and bleeding and recanalization.⁸ None of these complications were identified in the present study, and in our experience, small ureteral and urethral tears can be managed conservatively with temporary catheterization. Larger tears would likely require surgical repair.¹⁵

The most important factor limiting the widespread use of cystoscopic-guided transection is the need for specialized equipment and surgeon training. Costs associated with obtaining and maintaining a cystoscope and a diode laser or radiofrequency equipment make this procedure impractical for most general veterinary practices. Substantial costs can also be associated with laser safety training and equipment.

An important shortcoming of using cystoscopy to diagnose ureteral ectopia in dogs is the inability to examine the upper urinary tract. Dogs with ectopic ureters may have concurrent renal anomalies, including unilateral renal agenesis, hydronephrosis, or pyelonephritis.^2,6,8,16,17 Performing abdominal ultrasonography prior to cystoscopy could help identify these abnormalities and suggest a need for further diagnostic testing, such as excretory urography. Excretory urography and contrast cystourethrography were not routinely performed prior to laser ablation in the dogs in the present study because all dogs were assumed to have intramural ectopic ureters. During cystoscopic-guided transection, the course of the ureter was carefully evaluated to ensure that the ureter maintained a close association with the urethral lumen. Intraoperative contrast cystourethrography was performed in 1 patient to confirm that the ectopic segment of each ureter was intramural because this was not clear during cystoscopy. We recommend performing additional diagnostic imaging if the course of the ureter appears to diverge from the urethral lumen to avoid transection of urethral mucosa that is not associated with the ectopic segment of the ureter.

The cause of the hydronephrosis that developed post-operatively in 1 dog in the present study was unknown, although the surgeon (CAR) hypothesized that inflammation caused by laser incision may have caused ureteral stricture. Other potential causes of hydronephrosis include abnormal ureteral peristalsis, partial obstruction, and infection.² Hydronephrosis was not identified prior to cystoscopic-guided transection on excretory urograms nor was hydroureter evident during cystoscopy. In this patient, nephrectomy was performed by the referring veterinarian, and the kidney was not submitted for histologic examination. Therefore, the etiology of the hydronephrosis could not be confirmed. Although hydronephrosis requiring nephrectomy is a serious complication, it has been reported² in up to 8% (4/49) of cases following extravesicular ureteral transplantation for correction of ureteral ectopia. Further studies with larger patient numbers are necessary to accurately assess the etiology and risk of hydronephrosis following cystoscopic-guided transection.

There were 2 patients in the present study that had complete resolution of urinary incontinence following correction of only 1 ectopic ureter, a finding that has been reported² previously. In both of these patients, the orifice of the untreated ureter was within the cranial aspect of the urethra, which may have allowed retrograde passage of urine into the bladder.

Early in this case series, 2 patients received submucosal collagen injections at the time of cystoscopic-guided laser transection of ectopic ureters. At the present time, we believe that this practice is not indicated because the injected collagen may leak from the incised urethral mucosa into the urethral lumen.

The steep learning curve associated with cystoscopy and laser use makes the procedure described in the present report technically demanding. Although the outcome did not appear to improve in cases treated later in the series, median procedure time was shorter for dogs treated later in the series than for dogs treated earlier. Additionally, a polypropylene catheter or guide wire was inserted in the ureteral orifice during the procedure more often in cases treated later in the series. The catheter or guide wire served both to protect the dorsal and lateral ureteral walls and to aid in assessment of the intramural portion of the ectopic ureteral segment. No guide wire was used in 3 of the 4 cases in which complete ablation of 1 ureter was not achieved. Use of a metal guide wire is preferable to use of a polypropylene catheter to prevent damage to the dorsal and lateral ureteral walls when the diode laser is being used in contact mode. A catheter can be damaged by the laser, and use of an anodized metal guide wire reduces the likelihood of tissue injury from laser reflection.

A persistent vestibulovaginal band was identified in 6 of 16 patients in the present study. This band was routinely transected during cystoscopy because there is speculation that it provides dorsal traction to the urethral meatus and may contribute to incontinence. Further studies evaluating urinary continence before and after transection of this band are necessary to evaluate the clinical importance of transection of this band.

Major limitations of the present study were the small case numbers and the retrospective nature of data acquisition. Other limitations included the learning curve for the cystoscopic procedure, collection of outcome information from clients regarding urinary continence in their pets, and the fact that only 1 patient underwent intraoperative contrast urethrocystography.

Although the need for specialized equipment and advanced training limits the practical application of cystoscopic-guided transection, we believe that this procedure provides distinct advantages over traditional surgical correction. Similar outcomes may be expected, and most complications associated with cystoscopic procedures in the present study were minor and easily managed.