Diagnosis and Management of Ureteroceles in Two Female Dogs
Two intact female dogs were examined for refractory pollakiuria and stranguria. One of these two dogs also exhibited urinary incontinence. Ectopic ureteroceles were diagnosed via ultrasonography and cystoscopy in both dogs. Both dogs were taken to surgery for ureterocele resection and neoureterostomy, resulting in complete resolution of clinical signs. Although uncommonly reported in the veterinary literature, ectopic ureteroceles can be associated with recurrent lower urinary tract infection with and without urinary incontinence. With a correct diagnosis and appropriate treatment, prognosis for ectopic ureteroceles can be good provided there is not a concurrent significant loss of renal function.
Introduction
A ureterocele is defined as a cystic dilation of the submucosal segment of the distal ureter, often protruding into the bladder lumen.1 Ureteroceles may be located within the bladder, urethra, or both.1 Although not commonly described in the veterinary literature, ureteroceles can contribute to lower urinary tract disease (i.e., stranguria, pollakiuria, recurrent urinary tract infections) and also progressive loss of renal function. The purpose of this report is to describe the presentation, diagnostic plan, and treatment of ectopic ureteroceles in two intact female dogs.
Case Report
Case 1
A 4 mo old intact female cocker spaniel was presented for evaluation of a cystic structure located in the urinary bladder as detected by ultrasound by the referring veterinarian. The dog had a history of urinary incontinence that had been unresponsive to antibiotics. On presentation to Georgia Veterinary Specialists, physical examination was normal with the exception of an intermittent grade 1 out of 6 left apical systolic heart murmur and urine staining around the perineum. Packed cell volume, total solids, and a serum chemistry profile were evaluated. All results were within normal limits. A urine sample obtained by cystocentesis revealed urine with a yellow, hazy appearance, a specific gravity of 1.055, 1+ blood, a pH of 8.0, 2–5 white blood cells per high-power field (HPF), 20–30 red blood cells per HPF, rare bacteria noted (<8 per HPF), and amorphous debris present. Results of an aerobic urine culture performed from the same urine sample revealed Klebsiella pneumoniae with 1,000–10,000 colony-forming units (CFU)/mL. Results from susceptibility testing revealed resistance to ampicillin, carbenicillin, and ticarcillin. The organism was susceptible to the other antibiotics evaluated as part of the routine sensitivity panel (i.e., amikacin, augmentin, ceftazidime, ceftiofur, cephalothin, chloramphenicol, ciprofloxacin, enrofloxacin, gentamicin, nitrofurantoin, piperacillin, tetracycline, tobramycin, and tribrissen). Abdominal ultrasound was performed revealing marked dilation of the left renal pelvis and ureter (0.95 cm; reference range, 0.1–0.38 cm). A round, thin-walled structure containing anechoic fluid was found in the trigone region of the bladder (Figure 1). Immediately cranial to this structure, a focal, round dilation of the terminal left ureter was also noted. No other abnormalities were noted. Findings were consistent with left-sided pyelectasia, hydroureter, and suspected left-sided ureterocele. The dog was discharged and prescribed amoxicillin trihydrate/clavulanate potassiuma 125 mg per os (PO) q 12 hr for treatment of the urinary tract infection.
Citation: Journal of the American Animal Hospital Association 47, 2; 10.5326/JAAHA-MS-5618
Antibiotic therapy was continued for 4 wk until the dog presented again for cystoscopy. The vestibule appeared very hyperemic with follicular changes to the mucosa. A persistent paramesonephric remnant was identified (Figure 2). Moderate purulent discharge was seen from the vaginal opening. The urethra was noted to be hyperemic and very friable as the scope was advanced into the proximal bladder. The right ureteral orifice was identified in the normal anatomic location and urine was seen exiting this orifice. Extraluminal compression on the left dorsal bladder wall was noted, likely caused by the ureterocele previously identified on ultrasound exam. The left ureteral orifice could not be identified in this region of the bladder. The remaining bladder was examined and appeared hyperemic with increased vascularity. After examination of the bladder, the left ectopic ureteral orifice was identified in the distal urethra. The cystoscopic diagnosis was that of left ectopic ureterocele with termination in the distal urethra. A urine sample was obtained from the cystoscopy effluent during initial bladder entry and submitted for aerobic culture and sensitivity.
Citation: Journal of the American Animal Hospital Association 47, 2; 10.5326/JAAHA-MS-5618
A caudal ventral midline laparotomy was performed revealing the left ureter and renal pelvis to be markedly dilated. A ventral cystostomy was performed. The right ureteral orifice appeared within normal limits. The left ureteral orifice could not be identified in the bladder. The intramural portion of the ureter within the bladder was markedly dilated (i.e., a ureterocele). An incision was made into the dilated, intramural portion of the left ureter to create a new opening into the bladder (neoureterostomy). The portion of the ureter distal to the new opening was resected as far distally as possible and the mucosa closed with interrupted sutures using 5–0 polydioxanoneb. The ureter mucosa was anastamosed to the bladder mucosa with 5–0 polydioxanone. The bladder mucosa was closed over the resected ectopic ureter with 4–0 monocrylc. The bladder wall was closed in a routine manner with 4–0 monocryl. An indwelling foley catheter was placed to provide postoperative urinary drainage. A routine ovariohysterectomy was performed at the same time, then the abdomen was closed. No postoperative complications were noted and the urinary catheter was removed 2 days after surgery. Normal urinations were observed and the dog was then discharged and treated with tramadold 25 mg PO q 8 hr for 5 days as needed for pain relief, deracoxibe 12.5 mg PO q 24 hr for 5 days to decrease inflammation, and amoxicillin trihydrate/clavulanate potassiuma 125 mg orally q 12 hr for 7 days for possible urinary tract infection.
Urine culture results from the urine obtained during the cystoscopy were consistent with K. pneumoniae with greater than 100,000 CFU/mL. Due to persistent infection, the amoxicillin trihydrate/clavulanate potassium was discontinued 3 days after discharge from the hospital, and the dog was then prescribed trimethoprim-sulfadiazinef 480 mg PO q 12 hr. Recommendations were made to repeat the urine culture in approximately 7–10 days while the dog was still being treated with antibacterial medication, but the owner did not return for the recommended follow-up evaluation.
Approximately 1 yr from the date of surgery, telephone communication with the owner revealed that the dog was clinically normal, with no signs of urinary incontinence or other signs of lower urinary tract disease. The owners reported that the incontinence took approximately 1 to 2 wk to resolve after the time of surgery, but that the dog has been completely normal since that time.
Case 2
A 6 yr old intact female Labrador retriever was presented for evaluation of stranguria, pollakiuria, and urinating in the house. The dog had been unresponsive to empirical antibiotic therapy. No prior test results were provided for review and no urinary incontinence was noted by the owners.
On presentation, no significant abnormalities were noted on physical exam. The patient did urinate during the physical exam and voiding was associated with normal posturing, normal urine stream, and no incontinence. The urine was noted to be very malodorous. Results of a complete blood cell count, blood chemistry, and T4 concentration were unremarkable. A urine sample was obtained via cystocentesis and routine urinalysis and aerobic urine culture were performed. Urinalysis revealed urine with a clear and yellow appearance, a specific gravity of 1.015, a pH of 8.8, trace protein, 1+ blood, 3–6 white blood cells (with clumps noted) per HPF, and 2+ bacteria. No other abnormalities were noted. Aerobic urine culture isolated Corynebacterium spp. with greater than 30,000 CFU/mL. Abdominal ultrasound revealed a large (7.0 cm × 3.3 cm) cyst-like structure within the right dorsal urinary bladder in the region of the trigone. The structure consisted of a thin, echogenic wall surrounding anechoic fluid. The right ureter was identified dorsal and to the right of the urinary bladder. The ureter was tortuous and dilated (up to 1.1 cm in diameter) before tunneling into the dorsal urinary bladder submucosa and terminating in the cystic structure. The pelvis of the right kidney was dilated with anechoic fluid measuring approximately 1.0 cm in width. The proximal ureter measured 1.0 cm in diameter immediately adjacent to the right kidney. The left kidney and ureter were sonographically normal as was the rest of the abdomen. A sonographic interpretation of a right-sided ureterocele; right hydroureter; and mild, right-sided pyelectasia was made. Routine abdominal radiographs were performed prior to a glomerular filtration rate (GFR) evaluation and no abnormalities were noted.
Nuclear scintigraphy to evaluate GFR was then performed by injecting 3.5 mCi of technetium 99 DTPAg intravenously and acquiring dynamic images using a gamma camera and low energy collimator with the patient in dorsal recumbency for 6 min. Quantitative analysis could not be performed due to equipment malfunction, but morphologic data were obtained for the urinary system and both kidneys were interpreted as having a similar GFR as they had similar counts for the first 4 min postinjection. Subjectively, there was increased radioactivity in the right kidney compared with the left kidney in images acquired after 4 min due to radiopharmaceutical pooling in the dilated right renal pelvis and proximal right ureter. Morphologic findings were consistent with mild hydronephrosis and right hydroureter secondary to either ureteral obstruction or pyelonephritis.
A global GFR analysis was then performed to quantify overall renal function. This was achieved by injecting 89.5 mCi of technetium 99 DTPA intravenously then collecting serial serum samples. Counts of radioactivity were obtained in a well counter to derive a curve for calculation of total glomerular filtration. The global GFR was calculated to be 1.76 mL/min/kg (reference range, 1.92–3.5 mL/min/kg), which was consistent with renal insufficiency. Given the similar counts from the images obtained earlier, bilateral renal insufficiency was suspected.
The dog was treated with amoxicillin trihydrate/clavulanate potassiuma (375 mg PO q 12 hr) and the dog was discharged with plans to perform cystoscopy and surgery in the future. Within 1 week of treatment, the owners reported that the stranguria and pollakiuria had completely resolved. The dog was re-evaluated 1 mo after the original time of presentation. Urine culture was negative at that time and the dog was then lost to follow-up.
Approximately 1 yr later, the owners reported return of stranguria and pollakiuria. Clinical signs responded to antibiotics initially but returned once antibiotics were discontinued. A physical examination performed at that time revealed no significant abnormalities. A complete blood count and T4 concentration were normal. Blood chemistry revealed hypercholesterolemia (401 mg/dL, reference range, 80–315 mg/dL), hypernatremia (156 mEq/L; reference range, 143–153 mEq/L), and hypokalemia (3.2 mEq/L; reference range, 4.2–5.4 mEq/L). A urine sample was obtained via cystocentesis for submission of routine urinalysis and aerobic urine culture. Urinalysis revealed urine with a clear and yellow appearance, a specific gravity of 1.015, pH of 7.0, and trace bacteria. No other abnormalities were noted. Aerobic urine culture was negative. Abdominal ultrasound was again performed revealing an essentially unchanged, thin-walled, spherical structure filled with anechoic fluid within the lumen of the urinary bladder. The cystic structure, measuring 4.8 cm × 3.4 cm, had slightly decreased in size compared with the prior exam but now appeared to occlude the urinary bladder neck, filling the caudal urinary bladder lumen. Immediately adjacent to the cystic structure was a mildly dilated ureter with a diameter of 7.0 mm within the submucosa of the dorsal bladder wall. Compared with the previous images, the diameter of the right ureter had markedly decreased and was no longer visible along the majority of its length. The pyelectasia previously seen within the right renal pelvis was no longer present and both kidneys now appeared sonographically normal. The remainder of the abdomen was again sonographically unremarkable. Findings were consistent with persistent right-sided ureterocele, partially resolved right hydroureter, and resolved right pyelectasia.
Cystoscopy performed under general anesthesia revealed a normal vestibule and normal cingulum. The right ureteral orifice was found to be ectopic, located caudal to its normal location at the junction of the bladder and urethra (Figure 3). Severe dilation of the terminal ureter (ureterocele) could be visualized through the ureteral orifice (Figure 4). Extraluminal compression on the dorsal bladder wall was noted, likely caused by the ureterocele. The left ureteral orifice was also found to be ectopic, located in the dorsal wall of the proximal third of the urethra (Figure 5). The remainder of the bladder appeared within normal limits.
Citation: Journal of the American Animal Hospital Association 47, 2; 10.5326/JAAHA-MS-5618
Citation: Journal of the American Animal Hospital Association 47, 2; 10.5326/JAAHA-MS-5618
Citation: Journal of the American Animal Hospital Association 47, 2; 10.5326/JAAHA-MS-5618
Following cystoscopy, a caudal ventral midline laparotomy was performed. A ventral cystostomy was performed where both ureteral openings originated from a submucosal dilation encompassing most of the trigone of the bladder. Each ureteral opening was probed in a retrograde manner with red rubber catheters. The catheters were inserted into the ureteral openings and both catheters were found to enter into separate sides of the ureterocele. The ureteroceles were dissected from the bladder mucosa from their ectopic urethral opening to the level of their opening in the proximal bladder. A small amount of mucosa around each ureteral opening in the bladder wall was preserved (Figure 6). An indwelling foley catheter was placed to provide postoperative urinary drainage. Routine closure of the bladder wall and abdomen was performed. Histopathology of the bladder wall associated with the ureterocele revealed widespread submucosal edema with moderate to marked acute hemorrhage and multifocal, clear, cystic, dilated spaces occasionally lined by endothelium. No postoperative complications were noted. The urinary catheter was removed 1 day after surgery and the dog was urinating normally at that time. The dog was then discharged with a prescription for cephalexinh 500 mg PO q 12 hr for 14 days.
Citation: Journal of the American Animal Hospital Association 47, 2; 10.5326/JAAHA-MS-5618
Approximately 3 mo from the date of surgery, the owner reported that the dog was clinically normal, with no signs of stranguria or pollakiuria or other signs of lower urinary tract disease. The owners were again contacted approximately 3 yr after the surgery for follow-up information. The owners reported that the dog was still doing very well with no signs of lower urinary tract disease or other problems since the time of surgery.
Discussion
There have been several classification systems for ureteroceles proposed in human medicine. Stephens (1968) developed a system based on the size and location of the ureteric orifice, with four different categories being defined.2 These categories were defined as stenotic (narrow orifice within the bladder), sphincteric (wide orifice within the internal sphincter), sphinctero-stenotic (narrow orifice within the internal sphincter), and caeco-ureterocele (blind-ending ureterocele extending down the urethra).2 The majority of ureteroceles in humans involve a duplex collecting system (i.e., the kidney is divided into upper and lower poles, each drained by a separate renal pelvis and ureter). Churchill et al. (1992) went on to describe a grading system based on the total amount of renal tissue or renal units at risk for damage from obstruction or high-grade reflux. With grade 1 disease, only the ureterocele segment was affected. Grade 2 disease involved both segments of the affected kidney. In grade 3 disease, both kidneys were affected.3,4 The most frequently used system in humans, established by the American Academy of Pediatrics, classifies ureteroceles as intravesical (entirely within bladder) or ectopic (some portion situated permanently at the bladder neck or in the urethra).5 A classification system for dogs has been proposed using a modification of the Churchill functional classification system. This proposed system uses the functional classification used by Churchill et al., but also uses a grading system that takes into account the location of the ureterocele (i.e., intravesical versus ectopic); however, no system has been universally accepted in veterinary medicine.6
The etiology of ureterocele formation is unknown, but multiple theories exist.1 Many suspect that ureteroceles occur secondary to obstruction of the terminal ureter. It has been suggested that the anomaly may be caused by a persistent membrane (i.e., Chwalla membrane) with resulting obstruction at the fusion point between the mesonephric duct and urogenital channel.7 This could potentially explain ureteroceles that had a stenotic ureteral orifice, but does not explain ureteroceles with a patulous (distended) orifice within the urethra, as seen in two of the three ureteroceles described in this report. In case 1, the ureterocele terminated in the distal urethra with a large, patent opening. A similar finding was seen in the terminus of the right ureterocele described in case 2. Unlike obstruction of the ureter (which leads to diffuse dilatation and thinning of the ureter), ureteroceles involve a cystic dilation of the intravesicular ureter alone with excessive ureterocele musculature present.1 Tanagho (1972) went on to suggest that ureterocele formation may be related to the timing of absorption of the mesonephric (Wolffian) duct into the urogenital sinus, thus allowing the ingrowth of an abnormal amount of mesenchyme, leading to muscular dilatation. No single theory exists that explains all ureterocele formation.8
Ureteroceles have been commonly reported in humans, with the incidence at autopsy as high as 1 in 500. Clinically significant ureteroceles in humans are much less common, with an incidence in children of 1 in 5,000–12,000.9 Ureteroceles appear to be much more common in females (four to six times more frequent), and ectopic ureteroceles are four times more common than intravesicular ureteroceles.10,11 The majority of clinically significant ureteroceles occur in children and involve a duplex system and ectopic ureteral orifice.1 Alternatively, when ureteroceles are identified in adults, they are usually intravesicular, involve a single system (only one ureter), and usually do not cause kidney dysfunction or other significant clinical signs.12,13 Many presenting clinical symptoms for ureteroceles in humans have been reported including hematuria, urinary tract infections, obstructive voiding symptoms, urinary retention, and urinary incontinence.14
Ureteroceles have been described in small animals, but only a small number of cases have been reported. From 1971 to 2006, 18 cases have been described in the veterinary literature.15 This relatively low incidence rate may be attributed to the lack of clinical abnormalities often associated with ureteroceles. As previously discussed, the majority of human ureteroceles are diagnosed during routine ultrasound (pre- and postnatal), a procedure not typically performed in veterinary medicine. Unlike humans where duplex kidneys are commonly reported with ureteroceles, all ureteroceles reported in animals have involved a single system kidney.15 Clinical signs commonly reported with ureteroceles in dogs have included urinary incontinence, stranguria, pollakiuria, and dysuria.16 The dog in case 1 presented for evaluation of urinary incontinence, likely due to the ectopic nature of the ureterocele that was subsequently diagnosed. In case 2, the dog was evaluated for recurrent signs of lower urinary tract infection. The chronic infections this dog experienced were likely due to urine retention caused by the obstructive nature of the ureteroceles present. As seen on ultrasound, the ureteroceles occupied a large portion of the trigone region of the bladder, likely causing partial outflow obstruction of the urethra. It is interesting to note that this dog showed no signs of urinary incontinence, even though bilateral ectopic ureteroceles were later diagnosed. This is likely due to the very proximal location where the ureteroceles terminated into the urethra. The dog described in case 2 likely still retained enough urethral tone distally to remain continent.
There have been multiple imaging modalities described for the diagnosis of ureteroceles in veterinary medicine, including abdominal ultrasonography and abdominal radiography (i.e., excretory urogram and retrograde contrast cystogram).6,15 The cases described in this report differ from previously reported cases in that cystoscopy (in place of contrast radiography) was used to correctly diagnose the ectopic ureteroceles. Cystoscopy in female dogs has recently been shown to be a more reliable diagnostic tool in the diagnosis of ureteral ectopia as compared with excretory urography and contrast urethrography.17 In case 1, cystoscopy was performed to determine if the ectopic ureterocele was intravesical or ectopic. Since cystoscopy is a relatively short procedure that does not involve the use of contrast agents, the dog was able to be taken to surgery immediately following the procedure, thus allowing for a shorter hospitalization period. In case 2, the dog was first diagnosed with a unilateral ureterocele based on the results of abdominal ultrasonography. During cystoscopy, it was discovered that the patient had bilaterally ectopic ureters (later determined to be ureteroceles). Had this cystoscopy procedure not been performed, the patient's subsequent surgical procedure may have been prolonged or even incorrectly performed, not knowing that the patient had bilateral ectopia.
Numerous procedures have been described for the treatment of ureteroceles in dogs including ureteronephrectomy, endoscopic incision, neoureterostomy, neoureterocystostomy, ureterocelectomy, and ureterocele omentalization.15,18–24 The surgical procedures described in this report were similar to cases previously reported. Both dogs did extremely well postoperatively, with complete resolution of their clinical signs. The dogs in this report did not return for follow-up imaging after surgery so it is unknown if the initial pyelectasia and hydronephrosis described in each patient ever resolved. The dog in case 2, after treatment with antibiotics, did have resolution of pyelectasia based on ultrasound prior to surgery, suggesting that some of these initial findings could have been associated with concurrent urinary tract infection; however, a reduction in GFR was documented in the dog in case 2, suggesting some permanent changes associated with loss of renal function.
Conclusion
The cases described in this report and previous reports indicate that, although uncommon, ectopic ureteroceles can be associated with recurrent lower urinary tract infection with and without urinary incontinence. With a correct diagnosis and the appropriate surgery, prognosis for ectopic ureteroceles can be good provided there is not a concurrent significant loss of renal function.
Ultrasound image of the ureterocele diagnosed in case 1.
Cystoscopic view of the cingulum obtained of case 1. A: The left ectopic ureteral orifice in the dorsal wall of the terminal urethra. B: The terminal urethra. C: The persistent band of tissue spanning the vaginal opening (also known as a persistent paramesonephric remnant).
Cystoscopic view of the ectopic right ureteral orifice in case 2 (A) in the dorsal wall of the urethra (B). Note the position just distal to the junction of bladder and urethra (C).
Cystoscopic view of the patulous ectopic right ureteral orifice (A) leading into the right sided ureterocele in case 2.
Cystoscopic view of the ectopic left ureteral orifice (A) in the dorsal wall of the urethra in case 2.
Intraoperative view of the bladder lumen in case 2. The bladder was incised, exposing the mucosal surface of the dorsal bladder wall. Note the bladder mucosa (A) that was preserved during ureterocele excision. Red rubber catheters were inserted into the external ureteral orifices, which had been moved to their normal anatomic location in the trigone.
Contributor Notes
T. Green's present affiliation is Small Animal Medicine and Surgery Department, St. George's University School of Veterinary Medicine, Grenada, West Indies.
J. Arble's present affiliation is Veterinary Imaging Consultants, Parker, CO.
