Introduction

A ureterocele is a congenital cystic dilatation of the terminal ureter that occurs rarely in small animals. The ureterocele may be completely within the urinary bladder (orthotopic) or may involve the bladder neck or urethra (ectopic), and it may create increased outflow resistance and partial urinary obstruction of the ipsilateral and/or contralateral ureter, resulting in hydroureter and hydronephrosis.^1,2 The aims of surgical treatment of ureteroceles are to preserve renal function, prevent urinary outflow obstruction of both ureters and the urinary bladder, and maintain continence.¹ Previous authors have reported ureterocelectomy with or without neoureterocystostomy for the treatment of ureteroceles via an open surgical approach.^1,3 However, the first-line treatment of ureteroceles in humans is by cystoscopic-guided laser ablation, a technique that offers a minimally invasive intervention with good reported outcomes and low rates of reoperation.^4,5

Case Report

A 7 mo old 20.5 kg female entire golden retriever was referred for evaluation of urinary incontinence. Nocturnal urinary incontinence was reported but urination patterns at all other times were normal. She was otherwise reported to be in excellent general health. Clinical examination identified a small and slightly recessed vulva but was otherwise unremarkable. The dog was hospitalized and routine hematology and biochemistry were performed. These identified mild lymphocytosis (5.00 × 10⁹/L [1.0–4.8 × 10⁹/L]) and mild elevations in phosphate (2.6 mmol/L [0.6–1.4 mmol/L]) and alkaline phosphatase (151 IU/L [14–105 IU/L), all considered most likely to be age-related features. The problem list at this time was the presence of urinary incontinence with a small recessed vulva, and with consideration of the signalment of the dog, the top differential diagnoses were ureteral ectopia (and other congenital urinary tract abnormality), urinary tract infection, urethral sphincter mechanism incompetence, and presence of a ureterocele. Neurological conditions of the bladder were considered less likely owing to normal micturition during the day. The dog was sedated with 2 μg/kg of IV dexmedetomidine^a and 0.2 mg/kg IV butorphanol^b for focal urinary tract ultrasonography and cystocentesis, performed by a European College of Veterinary Diagnostic Imaging board-certified specialist. Examination revealed severe bilateral pyelectasis with reduced renal corticomedullary distinction, with changes more marked on the right—the pyelectasis on the right was 2.3 cm in width with a loss of the normal pelvic shape and 1.1 cm on the left. There was marked distension (≤1.9 cm diameter) of the right ureter throughout its course with a broad opening into a large, ectopic ureterocele emptying into the urethra (Figures 1A, B). The left ureter was moderately distended (≤7.5 mm diameter) throughout its length; however, the ureteral papilla was not visualized. Urinalysis of a sample obtained by cystocentesis identified 10–15 white blood cells per high-power field with evidence of large numbers of intracellular rods and cultured Escherichia coli, sensitive to potentiated amoxycillin.

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Diagnosis of an intramural right ectopic ureterocele with bilateral ureteral distention and secondary complicated urinary tract infection was made. The dog was discharged with a planned 6 wk course of 20 mg/kg amoxicillin-clavulanate^c per os q 12 hr. Repeat urinalysis 1 wk later identified no further signs of urinary infection or inflammation.

On re-evaluation after 5 wk, the owner reported that the dog had been continent since the instigation of antibiotic therapy and no other urinary signs had been noted. Physical examination remained unremarkable. Repeat ultrasonography of the urinary tract revealed progression of the previously reported structural abnormalities, with worsening bilateral pyelectasis (right 2.8 cm, left 1.6 cm). Following administration of 1 mg/kg IV furosemide^d, it was possible to visualize ureteral peristalsis bilaterally. A urine jet was visible from the left ureteral papilla, located adjacent to the ureterocele in a normal location but suggesting that the right-sided ureterocele may be obstructing drainage of the contralateral left ureter. Renal biochemical parameters remained within normal limits. The dog was discharged with instructions to complete the prescribed antibiotic course, prior to surgical assessment.

Six days later, the dog was admitted to the hospital for cystoscopic lower urinary tract evaluation and was reported to have remained continent over this time. The dog was premedicated with 1.5 μg/kg dexmedetomidine^a and 0.2 mg/kg methadone^e administered IV. General anesthesia was induced with IV propofol^f given to effect and maintained using isoflurane^g in oxygen. Throughout anesthesia the patient was monitored with electrocardiography, noninvasive blood pressure monitoring, capnography, esophageal temperature probe, and pulse oximetry. Hartmann’s solution^h was administered at 4 mL/kg/hr, and three boluses of fentanylⁱ 1–2 μg/kg were given IV as a response to intraoperative tachycardia and hypertension. The patient was positioned in dorsal recumbency and the perineum aseptically prepared to facilitate exploration of the lower urinary tract, using a Stryker 1288HD camera system and a 2.7 mm, 30° rigid cystoscope with side access channel. The left ureter was confirmed to open into the bladder in a normal location in the trigonum vesicae (trigone of the urinary bladder), appearing to be partially obstructed by the large right-sided ureterocele. The right ureteral orifice was found to be a wide opening within the cranial pole of the ureterocele, which cystoscopically appeared as a partition of the bladder separated only by a thin, nonmuscular membrane (Figures 1C, D). This membrane continued distally beyond the trigonum vesicae and tapered into an incomplete partition midway along the length of the urethra (Figure 2A). Using a VELAS15 TG-120 gallium-aluminum-arsenide diode laser^j with a wavelength of 940 nm, the urethral partition was incised in a distoproximal direction to the level of the left ureteral papilla. Thereafter, six punctate holes were made within the ureterocele wall partitioning the bladder, using the laser, to fully decompress the ureterocele (Figures 2B, C). A retrograde urethrocystogram was performed using 50:50 320 mg/mL iodinated contrast^k with saline and C-arm fluoroscopy to ensure integrity of the lower urinary tract. Robenacoxib^l at 2 mg/kg was administered subcutaneously at the end of the procedure. Recovery from anesthesia was unremarkable and no additional analgesia was required. The dog was discharged from the hospital after 36 hr, with a further 2 wk of amoxicillin-clavulanate as previously prescribed and 1.5 mg/kg robenacoxib^l per os once daily for 7 days.

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Three weeks later, the owner reported that the dog remained fully continent. Ultrasound re-examinations demonstrated ongoing but significantly reduced pyelectasis (right 1.5 cm, left 1.1 cm). Bilateral hydroureter remained, with urine jets observed bilaterally within the trigone. Urinalysis performed on a cystocentesis sample was unremarkable with negative culture. The owner reported the dog remained completely continent at a 3 mo follow-up telephone interview.

Discussion

Cystoscopy is required for the accurate diagnosis and surgical planning for ureteroceles, and minimally invasive procedures performed via cystoscopy are associated with shorter hospitalization and decreased postoperative pain in both the human and veterinary populations.^5–7

Various endoscopic laser techniques exist in the human literature for ureterocele decompression including simple incision, unroofing, and the “watering can technique,” whereby multiple (10–20) punctate holes are made within the intravesicular portion of a ureterocele to achieve decompression with the proposed benefit of reducing ureteral reflux.^4,8 Cystoscopic-guided laser ablation for the treatment of ureteroceles has only recently been described within the veterinary literature. In a report by Auger and others in 2018, the single orthotopic ureterocele was incised circumferentially around its base, excising the ureterocele in its entirety.⁹ In the report by Meler and others in 2018, in a case series of 16 dogs with congenital ureteral stenosis, the 4 dogs with ureteroceles were managed by simple incision.¹⁰ In two dogs with orthotopic ureteroceles, this involved the retrograde insertion of a guidewire into the ureter and incision of the medial wall of the intramural component until the ureteral orifice was cranial to the trigonum vesicae. For those dogs with ectopic ureteroceles, the laser was applied to the bulging intramural component of the ureterocele until the ureterocele lumen could be visualized, permitting insertion of the guidewire.¹⁰ In our report, we performed simple incision of the ectopic portion of the ureterocele along the length of the urethra and bladder neck with the addition of punctate holes to manage the intravesicular component of the ureterocele. This technique permitted full decompression of the ureterocele, relieving the urinary obstruction of both the ipsilateral and contralateral ureters, and removed the intraurethral component of the ureterocele. It was possible to advance the cystoscope into the distal orifice of the ureterocele to directly visualize the ureteral opening in this case, and thus, it was not deemed necessary to use a guidewire to assess the intramural extent of the ureterocele.

Laser incision of intramural ectopic ureters under cystoscopic guidance is now commonly performed in the veterinary field and has been shown to be safe and effective, with success rates comparable to open surgery.¹¹ Possible complications include urethral or ureteral perforation and subsequent uroabdomen or uroretroperitoneum requiring open surgical correction, although this is rare with appropriate preoperative imaging and operator training.¹² Neither of the reports in the veterinary literature of ureteroceles managed via cystoscopic-guided laser ablation experienced major intraoperative or postoperative complications related to the technique used.^9,10 Cystoscopic-guided techniques are possible in dogs of all sizes, with respective cystoscope diameter previously reported.¹² In male dogs, it may be necessary to perform initial examination with a flexible endoscope, subsequently obtaining percutaneous perineal access to the pelvic urethra via the modified Seldinger technique allowing rigid cystoscopy if required.¹²

Conclusion

Ureteroceles are a rarely encountered, congenital urinary tract abnormality that can cause ureteral flow obstruction with subsequent hydroureter, hydronephrosis, and azotemia. Cystoscopic-guided laser ablation is the treatment of choice in humans and has recently been described in dogs. This case demonstrates the effective use of cystoscopic-guided laser ablation with the addition of the “watering can” technique for the treatment of an ectopic ureterocele in a canine patient. This approach appears to be a safe, precise, minimally invasive, and effective method for ureteroceles in appropriate cases following thorough preoperative investigation.