Clinical Outcomes of Surgically Managed Ectopic Ureters in 33 DogsS
Factors that predict postoperative continence and incontinence were evaluated in 33 female dogs with surgically corrected ectopic ureters. The current study found that intramural or extramural, left- or right-sided, and unilateral or bilateral ectopic ureters were not significant factors influencing postoperative incontinence in affected dogs. The presence of either hydroureter or urinary tract infection was also not significantly associated with postoperative incontinence. Dogs with ectopic ureters that were incontinent postsurgically tended to remain unresolved.
Introduction
Ectopic ureter is a congenital abnormality in which the ureteral orifice terminates at a position other than the trigone of the urinary bladder. This anomaly arises from the abnormal origin and migration of the ureteral bud along the mesonephric duct.1 In males, termination of the ureter has been reported in the vas deferens, seminal vesicles, and urethra, whereas in females, it has been noted to terminate in the cervix, uterus, oviduct, and urethra.2 The presence of an ectopic ureter is often associated with other urinary tract anomalies, including renal aplasia, renal hypoplasia, ureterocele, hydronephrosis, hydroureter, ureterovesicular abnormalities, pelvic bladder, and urethral sphincter mechanism incompetence.2
An ectopic ureter is classified as either intramural or extramural based on the course of the ureter to its terminal orifice. An intramural ectopic ureter is defined as a ureter that courses through the mucosal and submucosal layers of the bladder to exit in the bladder neck, urethra, or vagina. The formation of ureteral troughs, fenestrations, and branching may also be present.3 An extramural ectopic ureter is defined as a ureter that completely bypasses the bladder to enter the bladder neck, vagina, vestibule, uterus, or urethra.
Clinical presentation of dogs with an ectopic ureter is most often related to either continuous or intermittent urinary incontinence since birth or purchase, with most patients <1 yr of age. Studies have identified certain breeds that are over-represented with ectopic ureters, including the Siberian husky, golden retriever, Labrador retriever, Newfoundland, poodle, fox terrier, and Skye terrier.3–10 The incidence in female dogs are reportedly 20× more prevalent than males.11 An epidemiologic study by Hayes (1974) revealed a ratio of 25:1 females versus males being diagnosed with ectopic ureters from 100,000 dogs.9 Ectopic ureters in cats are rare, with only 24 cases described in the veterinary literature.12
Diagnosis of an ectopic ureter has involved using different methods and/or combinations of imaging studies, including excretory urography, pneumocystography, retrograde vaginography, urethrography, ultrasonography, computed tomography (CT), and magnetic resonance imaging.3,4,13,14 The use of cystoscopy or advanced imaging is superior to other established imaging studies in determining the definitive diagnosis of ectopic ureter, its morphology, and other congenital abnormalities of the urogenital tract.3,14
Surgical correction of an ectopic ureter involves one of three techniques: neoureterostomy (i.e., creation of a new stoma in the region of the trigone of the bladder), neoureterocystostomy (i.e., reimplantation of the ureter into the bladder), or nephroureterectomy (i.e., excision of the affected kidney and its ureter). Evaluation of a functional contralateral kidney is required if a nephroureterectomy is indicated.
The current study examined 33 dogs with surgically treated ectopic ureters and their postoperative outcomes. The type and location of the ectopic ureter, method of surgical correction, and postoperative outcome (i.e., continent or incontinent) were evaluated.
Materials and Methods
Case Selection
Medical records of patients diagnosed with an ectopic ureter at the Veterinary Teaching Hospital (VTH), Virginia-Maryland Regional College of Veterinary Medicine from 1986 to 2007 were retrospectively reviewed. The selection criteria included dogs that were surgically treated for ectopic ureter(s) and that received postoperative client communications by recheck examination at the VTH, a completed questionnaire by the owner, or telephone inquiries (see Supplementary Appendix). In total, 33 dogs matched these criteria.
Medical Records Review
Medical records were reviewed for signalment, presenting complaint(s), duration of clinical signs, results of diagnostic procedures, method of surgical repair, and postoperative medication. Follow-up client communication specifically assessed urinary continence based either on recheck examination at the VTH or a standardized questionnaire completed by mail or telephone conversation.
The diagnostic procedures performed were survey and contrast radiography (i.e., nephrography, excretory urography, and cystography), ultrasonography, cystoscopy, and surgery. The ectopic ureter was classified as right, left, or bilateral. The type of ectopic ureter was classified as either intramural or extramural. Urogenital abnormalities, such as urinary tract infection and hydroureter, were recorded. The use of urodynamic studies, such as urethral pressure profilometry, was also evaluated.
Surgical techniques used in the correction of ectopic ureters were neoureterostomy, neoureterocystostomy, and nephrectomy with ureterectomy. Other surgical procedures conducted at the time of ureteral correction included ovariohysterectomy, colposuspension, episiotomy, cystopexy, and partial vaginectomy.
The outcome of surgical treatment was assessed by the presence or absence of urinary incontinence postsurgically. Incontinence was based on the owner's perception of any episode of involuntary control of urination, whether at rest, excitement, or stress. The use of postoperative medication such as phenylpropanolamine and estrogen for treatment of urinary incontinence was also recorded.
Surgical repair of ectopic ureters was performed by board certified surgeons or supervised surgical residents. Intramural ectopic ureters were corrected by neoureterostomy and extramural ectopic ureters were corrected by neoureterocystostomy. The presence of unilateral renal dysplasia or significant renal pathology dictated nephroureterectomy.
In all cases, a ventral midline celiotomy was performed, followed by a complete abdominal exploration. Surgical identification of an intramural ectopic opening was performed by one of three methods: preoperative retrograde ureteral catheterization by cystoscopy; direct visualization of the ectopic opening; or intraoperative distension of the ureteral lumen by digital occlusion of the urethra and ureter. An incision was then made through the bladder mucosa into the ureteral lumen in the area of the trigone of the bladder. The ureteral mucosa and bladder mucosa were apposed using a simple interrupted pattern with absorbable, monofilament sutures. One of two methods was used to occlude the distal ureteral segment: (1) circumferential sutures were placed around the distal segment of the ureter as a mass ligation technique; or (2) the distal ureteral segment was ligated proximally near the new stoma and excised as distally as possible.
An extramural ectopic ureter was ligated and transected as close to its distal attachment as possible. The terminal end of the ureter was spatulated and reimplanted in an avascular area of the trigone of the bladder. Absorbable, monofilament sutures were used in a simple interrupted pattern to anastomose the ureteral mucosa to the bladder mucosa. A nephroureterectomy was performed by elevating the affected kidney from the surrounding mesentery and sublumbar attachments. The renal artery and vein were identified and ligated. The associated ureter was ligated as close to the bladder wall as possible and resected with the kidney.
Statistical Analysis
Multiple factors were analyzed to determine associations with the presence or absence of urinary incontinence. These included: anatomic location (left or right); type (intramural or extramural); unilateral or bilateral ectopic ureter; the surgical technique performed (i.e., neoureterostomy, neoureterocystostomy, or nephroureterectomy); the presence of a urinary tract infection; the presence of hydroureter; and follow-up client communication <12 mo or >12 mo. Frequencies of categorical variables associated with clinical features and treatment responses were compared using χ2 test of independence. Statistical calculations were considered significant if P≤0.05.
Results
Fifty cases of ectopic ureters were diagnosed at the VTH in a 21 year period, consisting of 49 dogs and 1 cat. Cases were excluded based on absent client follow-up communication (6/50), no surgical treatment (5/50), missing medical records (4/50), wrong species (1/50), and death in the immediate postsurgical period (1/50). Ultimately, 33 dogs met the inclusion criteria.
All dogs included in the study were female comprising 10 different breeds. The Labrador retriever represented 54% of cases (18/33). Other breeds included the Siberian husky (3/33), golden retriever (2/33), Newfoundland (2/33), bulldog (2/33), and one each of: Chesapeake terrier; Lakeland terrier; rottweiler, Tibetan spaniel; Irish wolfhound; and mixed-breed. Median age at presentation was 5 mo (range, 1 mo to 4 yr) and median body weight was 20 kg (range, 3–55 kg).
The primary complaint on presentation was urinary incontinence since birth or purchase in 75% (25/33) of cases. Twenty-one percent (7/33) presented for urinary tract infections and 15% (5/33) presented for both urinary incontinence and urinary tract infection. One dog was referred specifically for azotemia detected prior to routine ovariohysterectomy and another for recurrent urinary tract infections with a cystic structure identified during a routine ovariohysterectomy.
Eighteen cases had follow-up client communication <12 mo and 15 cases had follow-up client communication >12 mo postoperatively. In the group with a follow-up time <12 mo, 66% (12/18) of cases remained incontinent. Fifteen of these cases were re-examined at the VTH. The remaining three cases completed a questionnaire by mail or telephone. Sixty percent (9/15) of cases with follow-up communication >12 mo postsurgically were incontinent (Table 1). Three of these cases were re-evaluated at the VTH. The median follow-up time was 6 mo (range, 7 days to 8.25 yr). There was no significant association with follow-up period postsurgically and the incidence of urinary incontinence (P=0.69). The overall incidence of incontinence postsurgically was 58% (19/33).
Seventy-three percent (24/33) of affected dogs had a positive urinary culture preoperatively. Escherichia coli was the predominate organism isolated in 54% of dogs (13/24). Other isolated bacteria included Proteus spp. (6/24), Pseudomonas aeruginosa (3/24), Enterococcus spp. (2/24), and Staphylococcus intermedius (1/24). Two dogs had a mixed bacterial population. Fifty percent (12/24) of dogs with preoperative urinary tract infections remained incontinent postsurgically. There was no significant association with the presence of urinary tract infection and postoperative urinary incontinence (P=0.15).
Identification of ectopic ureters included the use of various diagnostic imaging studies: contrast radiography (7/33, Figure 1); cystoscopy (3/33, Figures 2A–C); contrast radiography and cystoscopy (4/33); cystoscopy and ultrasonography (5/33); ultrasonography and contrast radiography (3/33); and all three combinations (11/33). Urodynamic studies, such as urethral pressure profilometry, were performed in five patients, but these results were not statistically assessed based on limited results. Nonetheless, all five of these patients had maximal urethral closure pressures of 15–21 cm H2O. Three of these cases became continent postsurgically.
Citation: Journal of the American Animal Hospital Association 47, 3; 10.5326/JAAHA-MS-5495
Citation: Journal of the American Animal Hospital Association 47, 3; 10.5326/JAAHA-MS-5495
A unilateral ectopic ureter was identified in 60% (20/33) of cases, with 50% (10/20) remaining incontinent postoperatively. Bilateral ectopic ureters were identified in 40% (13/33) of cases, with 69% (9/13) remaining incontinent postoperatively. Two cases with bilateral ectopic ureters had one intramural and a contralateral extramural ureter. Both cases remained incontinent postsurgically. All other bilateral ectopic ureters were intramural. The presence of either unilateral or bilateral ectopic ureter(s) did not significantly affect postsurgical incontinence (P=0.27). A unilateral left ectopic ureter was identified in 75% (15/20) of cases, with 53% (8/15) remaining incontinent postoperatively. A unilateral right ectopic ureter was identified in 25% (5/20) of cases, with 40% (2/5) remaining incontinent postoperatively (Table 2). There was no significant difference in postsurgical incontinence between animals affected with either a unilateral left or right ectopic ureter (P=0.60).
An intramural ectopic ureter was diagnosed in 87% (40/46) of affected ureters. Fifty-two percent (24/40) were incontinent postsurgically. Thirteen percent (6/46) of affected ureters were diagnosed as an extramural ectopic ureter, with 9% (4/46) remaining incontinent postsurgically (Table 2). A statistically significant association was not found with either an intramural or extramural ectopic ureter and postsurgical incontinence (P=0.75).
A neoureterostomy was performed on 74% (34/46) of the ectopic ureters identified, with 67% (23/34) of cases remaining incontinent following surgery (9 of these cases underwent bilateral neoureterostomy). A neoureterocystostomy was performed on 11% (5/46) of affected ureters, with 60% (3/5) of cases remaining incontinent following surgery. The remaining 15% (7/46) of the cases had a nephroureterectomy performed, with 43% (3/7) remaining incontinent following surgery (Table 3). The indications for nephroureterectomy included: renal dysplasia (2/7); severe hydronephrosis (2/7); hydroureter with ureterocele (2/7); and hydroureter with nephrolith and ureterolith (1/7). One case underwent a neoureterostomy and a contralateral neoureterocystostomy, with continence achieved. Two cases underwent neoureterostomy and contralateral nephroureterectomy, but both remained incontinent postsurgically. There was no significant difference between surgical procedure performed and postoperative outcome (P=0.46).
Urinary incontinence was assessed for cases that underwent a neoureterostomy with the distal ureteral segment either ligated (only) or ligated and excised as distally as possible. There were 47% (16/34) of distal ureteral segments that were ligated and 63% (10/16) were incontinent postoperatively. Twenty-six percent (9/34) had the distal ureteral segment ligated and excised as distally as possible, with 67% (6/9) remaining incontinent postoperatively. There was no statistical analysis performed as nine cases had incomplete surgical reports.
The presence of at least one hydroureter was identified in 57% (19/33) of cases. Fifty-eight percent (11/19) of these cases were incontinent postsurgically. Six cases had bilateral hydroureters (Table 4). The presence of a hydroureter was not significantly associated with postoperative incontinence (P=0.96). Other urogenital abnormalities observed intraoperatively included: a pelvic bladder (2/33); cystine nephroliths (1/33); pyelonephritis (2/33); hydronephrosis (10/33); ureterocele (2/33); renal medullary cyst (1/33); vaginal stricture (1/33); and vaginal cyst (1/33). Cases that remained incontinent postsurgically after identification of these anomalies included one dog with a pelvic bladder and another with a ureterocele.
Concurrent surgical procedures performed at the time of surgical correction for the ectopic ureter(s) included: colposuspension (2/33); ovariohysterectomy (6/33); episiotomy (1/33); cystopexy (1/33); and partial vaginectomy (1/33). Two cases that underwent colposuspension and four cases that underwent ovariohysterectomy remained incontinent postsurgically.
Ten dogs received medication for postoperative urinary incontinence, including phenylpropanolamine (9/10) and estrogen (1/10). Three dogs achieved continence while on medication postsurgically. The dosage and duration of medical therapy were not assessed due to incomplete medical records.
Discussion
Although ectopic ureters are the most common cause of incontinence in the juvenile animal, its reported prevalence is only 0.016–0.045%.8,9,15 The median age at presentation ranges from 5–10 mo, which is similar to ages of the dogs included in the current study.3,8 A genetic etiology for ectopic ureters has been suggested due to overrepresentation of certain breeds. These include: the Siberian husky; toy poodle; West Highland white terrier; Labrador retriever; golden retriever; Shetland; fox terrier; and Skye terrier.4,6,9 Familial aggregations of ectopic ureters have been reported in Labrador retrievers and Siberian huskies.16 The apparent overrepresentation of Labrador retrievers in this study should be interpreted with consideration, as breed representation of the general hospital caseload was unavailable.
The presence of unilateral or bilateral ectopic ureters has previously been reported to have no association with postsurgical urinary incontinence, which was also observed in this study.3,17,18 Interestingly, one report relayed that incontinence improved or resolved in some dogs affected bilaterally that had only one ectopic ureter corrected.8 This demonstrates that some dogs can regain continence despite the presence of an ectopic ureter. Although more left-sided than right-sided ectopic ureters were identified in the present study, the anatomic side was not clinically significant to postsurgical outcome.
The influence of intramural versus extramural ectopic ureters in relation to urinary incontinence has not been well documented. In the current study, there was no association with the type of ectopic ureter and postsurgical outcome. The incidence of intramural ectopic ureters was reported more commonly than extramural ectopic ureters in the dog, which was supported by the current study.8 The difficulty in determining the course of an intramural ectopic ureter may have contributed to the lower incidence of this recorded type, leading to the ureter being mislabeled as extramural. Unfortunately, due to incomplete medical records and the lack of standardized diagnostic imaging performed, the exact termination sites could not be determined.
Various imaging procedures for identification of an ectopic ureter have been evaluated in previous studies. Excretory urography combined with pneumocystography have been suggested to increase diagnostic accuracy compared to excretory urography alone, as misdiagnoses have been reported due to superimposition of pelvic structures.3,4,13 Contrast radiographic studies were also reported to have substantial discordance from surgical findings.13 The use of cystoscopy has significantly improved the identification of ectopic ureteral openings and other anomalies, especially for evaluation of extramural ureters.3 Transurethral cystoscopy was useful for improved examination of the vestibule and identification of paramesonephric septal remnants, fenestrations, and urethral mucosal changes.3 More recently, Samii et al. (2004) proposed CT as the diagnostic modality of choice for identification of ectopic ureters.14 Contrast-enhanced CT was more useful and noninvasive than other imaging techniques, especially for determining the site of ureteral termination. In humans, CT with delayed contrast is the most sensitive test for diagnosis of ectopic ureters and termination of the ureteral orifice.11 Surgical exploration will be required to determine the type of ureter present when preoperative diagnostics are inconclusive. Due to the retrospective nature of this study, standardized preoperative imaging techniques could not be achieved, as this was primarily based on clinician preference, equipment availability, and clients' financial constraints.
Further evaluation is required to assess the role of urodynamic studies in patients with urinary incontinence. There is a wide variability in measurements of urethral pressure profiles in the dog, with one study showing a mean normal pressure of 23.9 mm Hg (32.5 cm H2O) in female dogs and 28.3 mm Hg (38.5 cm H2O) in male dogs.19 Another study had maximal urethral closure pressures of 17.7–62.6 cm H2O in healthy intact bitches, which is higher than the measurements of the current study (15–21 cm H2O).20 It should be taken into account that the values reported herein were preoperative measurements of incontinent bitches. Mayhew et al. (2006) reported a lower maximal urethral pressure in dogs that remained incontinent postsurgically compared with dogs that achieved continence.17
A comparison of the three surgical techniques in this study supported the reported rate of incontinence of 26–63% following surgical correction of ectopic ureters.4,5,7,8,17,18 Possible explanations for persistent incontinence postsurgically include: distal remnants of the ectopic ureter traversing the bladder neck and interfering with normal sphincter function; concomitant sphincter incompetence; recanalization of the distal ureteral segment; hypoplastic bladder; and vestibulovaginal stenosis. Ureteral branches that were not identified or treated at surgery can result in persistent urinary incontinence, thus excretory urography is recommended in dogs remaining incontinent after surgical correction.3,4 It is debatable whether ligation of the ureter without resection of the distal ureteral segment during a neoureterostomy would increase the risk of postsurgical incontinence. Comparisons of the two techniques did not find any significant difference in postsurgical incontinence.17,18 The main complications associated with neoureterocystostomy include stricture formation at the implantation site and vesicoureteric reflux.6,8 A nephroureterectomy would be indicated if significant renal pathology, such as severe hydronephrosis, hydroureter, or renal dysplasia, is present, provided that there is an adequately functional contralateral kidney. Fewer complications occur after nephroureterectomy than ureteral transplantation.8
The presence of hydroureter is reported to be the single most common abnormality associated with ectopic ureters (Figures 3 and 4).13,21 Postoperative development of hydroureter may be due to bladder wall edema and interference with normal ureteric peristalsis, leading to stricture at the implantation site or vesicoureteric reflux.6 The reversal of hydroureter appears less likely after extravesicular than intravesicular transplantation.8 Other urogenital anomalies, such as urinary tract infections, are shown to have no association with postoperative incontinence, as was observed in the current study.17 Use of antibiotics may play a role in alleviating the severity of clinical signs. Other medications including α-adrenergic agonists or hormonal supplements should be further studied to assess their influence on postsurgical outcome. Interestingly, short-term (<12 mo) or long-term (>12 mo) follow-up communications did not show significant differences in achieving continence following surgery. Dogs that appeared continent postsurgically may become incontinent with time. Radiographic examinations were not repeated routinely after surgery and this may have led to an underestimation of the number of postoperative complications.8
Citation: Journal of the American Animal Hospital Association 47, 3; 10.5326/JAAHA-MS-5495
Citation: Journal of the American Animal Hospital Association 47, 3; 10.5326/JAAHA-MS-5495
Conclusion
The strength of association of ectopic ureters in certain purebreed dogs and the lack of reported incidences in mixed-breeds supports the likelihood that familial genetics play a role in this congenital condition.16 Limitations of the current study include the subjectivity and length of follow-up communications and the small case numbers in determining the significance of specific factors that were studied. Other aspects that could be further assessed include: ureteral termination sites; the presence of ureteral troughs and fenestrations; and the use of concurrent medication for both urinary tract infections and urinary incontinence. This study found that the type and location of an ectopic ureter, the surgical technique performed, and the presence of hydroureter or urinary tract infections were not significant factors affecting postsurgical incontinence. Dogs that remain incontinent following surgery need careful re-evaluation to assure that correctable causes are ruled-out before prescribing lifelong medical therapy.5
Intravenous urogram. Note the abnormal termination of the ureter distal to the urinary bladder.
A: Cystoscopic image of the catheterization of an ectopic ureter. B: Cystoscopic image of an ectopic ureteral opening within the urethra, distal to the trigone of the bladder. C: Cystoscopic image of a paramesonephric remnant.
Intravenous urogram showing unilateral hydroureter and hydronephrosis.
Intraoperative photograph of a hydroureter and hydronephrosis.
Contributor Notes
L. Ho's present affiliation is Department of Veterinary Clinical Sciences, Louisiana State Univeristy, Baton Rouge, LA.
D. Waldron's present affiliation is the VCA Veterinary Care Animal Hospital and Referral Center, Albuquerque, NM.
The online version of this article (available at jaaha.org) contains a supplementary appendix.
