Dog Ureter Research Articles

Laparoscopic ureteroneocystostomy in the treatment of urinary incontinence due to ectopy of the ureters in female dogs: A pilot study.

Ureteral ectopia is rare and requires surgical treatment after a thorough diagnostic workup. Open surgical techniques for repositioning ectopic ureters have been known for many years and are well described in the literature. However, to the best of our knowledge, no laparoscopic method of correcting this pathology has been described, which, in our opinion, would benefit the animal in terms of the healing process and overall clinical outcomes. This study aimed to evaluate the possibility of laparoscopic treatment of ureteral ectopia, which causes urinary incontinence in dogs. All of the operated ten dogs presented in this study were client-owned females with symptoms of urinary incontinence due to a unilateral intramural ectopic ureter. A three-trocar laparoscopic technique was used to perform the ureteroneocystostomy of the ectopic ureter. In this article, clinicopathological data, imaging features, procedural findings, complications, and short- and long-term outcomes are presented. The procedure was feasible in all cases. No major postoperative complications were observed. Among the minor complications, slight hematuria was observed in three dogs, which resolved spontaneously. In the period of at least one year after surgery, no negative impact of the procedure was observed. Seven of the ten operated dogs regained urinary continence. The remaining three dogs required additional surgery (urethral bulking) because of a lack of improvement after adjuvant pharmacological treatment. Overall, good-to-excellent long-term outcomes can be achieved; however, dogs that remain incontinent after laparoscopic ureteroneocystostomy may require additional treatment.

Computed tomographic appearance of transcaval ureter in two dogs and three cats: A novel CVC congenital malformation.

Transcaval ureter is a rarely reported human congenital malformation of the prerenal segment of the inferior vena cava (IVC) not yet reported in veterinary medicine. The objective of this multicenter retrospective case series study was to describe the computed tomography (CT) features of transcaval ureters in dogs and cats. Patients referring to pre- and post-contrast CT exams of the abdomen and presenting this abnormality were retrospectively included. Multiple qualitative features were described for each ureteral abnormality detected. Three cats and two dogs with transcaval ureter were identified consisting of a segmental duplication of the CVC at the prerenal level creating a vascular ring through which the ureter extended, identified as a double-barrel gun sign. The malformation was divided into two types according to the symmetry of the caval branches and location in relation to the aorta, namely, type I symmetrical branches and right-lateral to the aorta, and type II asymmetrically branches and right-dorsal to the aorta. In one case, the malformation was associated with hydroureter and mild pyelectasis. In three cases, the anomaly was incidental and, in the remaining two cases, the clinical significance was uncertain. This is the first study describing the presence of transcaval ureter in dogs and cats. CT was a suitable method for the diagnosis of transcaval and a focal double-barrel gun sign of the CVC is proposed as the hallmark feature of this anomaly. The clinical relevance of this congenital vascular malformation is unclear and needs to be further investigated.

Cystoscopic-guided scissor transection of intramural ectopic ureters as a novel alternate minimally invasive treatment option to laser ablation in female dogs: 8 cases (2011–2020)

To evaluate the safety and efficacy of cystoscopic-guided scissor transection of ectopic ureters (CST-EU) in female dogs. 8 incontinent female dogs with intramural ectopic ureters. For this retrospective case series, data were collected from medical records of dogs that underwent CST-EU to relocate the ectopic ureteral orifice to an anatomically normal trigonal location between June 2011 and December 2020. Outcome after hospital discharge was determined using owner telephone questionnaires. Ectopic ureters were bilateral in 4 of the 8 dogs, and all dogs had other urogenital tract anomalies. Owner questionnaire follow-up was available for 7 dogs, and results indicated 6 dogs had improved urinary continence immediately following the procedure. At the last follow-up (44 to 3,384 days after CST-EU), 3 of the 7 dogs were completely continent with CST-EU alone, 3 others became continent or were markedly improved with the addition of medications for urethral sphincter mechanism incompetence, and 1 required ureteroneocystostomy, colposuspension, and an artificial urethral sphincter to become fully continent. Owners of 5 of the 7 dogs reported that they considered the outcome of CST-EU as good to excellent, and all owners reported that they would consider having CST-EU performed again should they have another incontinent dog. Complications were minor, and only 3 dogs showed transient lower urinary tract signs after CST-EU. Results indicated CST-EU could provide a safe, effective, minimally invasive alternative in the absence of laser technology for the treatment of intramural ectopic ureters in female dogs.

Comparison of static-fluid or excretory magnetic resonance urography with computed tomography urography for visualization of nondilated renal pelvises and ureters in healthy Beagles.

To assess the usefulness of magnetic resonance urography (MRU) for the visualization of nondilated renal pelvises and ureters in dogs and to compare our findings for MRU versus CT urography (CTU). 9 healthy Beagles. Dogs underwent CTU, static-fluid MRU, and excretory MRU, with ≥ 7 days between procedures. Contrast medium was administered IV during CTU and excretory MRU, whereas urine in the urinary tract was an intrinsic contrast medium for static-fluid MRU. For each procedure, furosemide (1 mg/kg, IV) was administered, and reconstructed dorsal plane images were acquired 3 minutes (n = 2) and 7 minutes (2) later. Images were scored for visualization of those structures and for image quality, diameters of renal pelvises and ureters were measured, and results were compared across imaging techniques. Excretory MRU and CTU allowed good visualization of the renal pelvises and ureters, whereas static-fluid MRU provided lower visualization of the ureters. Distention of the renal pelvises and ureters was good in excretory MRU and CTU. Distention of the ureters in static-fluid MRU was insufficient compared with that in CTU and excretory MRU. Distinct artifacts were not observed in CTU and excretory MRU images. Static-fluid MRU images had several mild motion artifacts. Our findings indicated that excretory MRU with furosemide administration was useful for visualizing nondilated renal pelvises and ureters of dogs in the present study. When performing MRU for the evaluation of dogs without urinary tract dilation, excretory MRU may be more suitable than static-fluid MRU.

Retrospective evaluation of cystoscopic-guided laser ablation of intramural ectopic ureters in female dogs.

BackgroundCytoscopic‐guided laser ablation (CLA) is a technique that can be used to correct intramural ectopic ureters (EUs) in dogs.Hypothesis/ObjectivesTo describe clinicopathologic, imaging, and cystoscopic findings in dogs undergoing CLA for intramural EU correction, and whether any of these findings are associated with continence outcomes.AnimalsThirty‐one client‐owned dogs undergoing CLA between 2009 and 2019.MethodsRetrospective cohort study. Data collected from medical records included signalment, clinical findings (including continence score at presentation), clinicopathologic findings (serum biochemistry profile, urinalysis, and urine culture results before CLA), ultrasonography, and cystoscopy findings. Follow‐up information was collected at 1 day to 1 week, 1 week to 1 month, and at >1 month time points after CLA. Final continence score was determined based on this follow‐up information. Multiple logistic regression was used to determine factors that were associated with final continence score.ResultsMedian continence score of dogs at initial evaluation was 2 (range, 2‐4). Median continence score after CLA alone was 3 (range, 1‐5). Seventeen of 31 (54.8%) dogs received adjunctive medical management after CLA. Median continence score after CLA with or without adjunctive medical management was 5 (range, 1‐5). Overall, 67.7% of dogs were considered continent after CLA with or without adjunctive medical management. No preoperative or perioperative factors were found to be associated with final continence score.ConclusionsCystoscopic‐guided laser ablation for intramural EU in female dogs provides improvement in incontinence. Dogs remaining incontinent after CLA may improve with adjunctive medical management. Surgical management is required to manage incontinence in dogs with extramural EU.

Intramural ectopic of the ureter in dogs

Intramural ectopic of the ureter in dogs

Ureteral Stent Placement Using a Double J-Catheter in the Treatment of Ectopic Ureter in a Dog

Background: Ectopic ureter is a congenital anomaly in which the final segment of one or both ureteral orifices is located distal to the bladder trigone. It may be classified as intra- or extramural. Surgical treatment of ectopic ureters in dogs is recommended and the approach varies with the classification. In the postoperative period, complications are common. When stenosis of the new ureteral ostium occurs, immediate repeated surgery is recommended. This study aimed at using the double J catheter placement following neoureterostomy to treat urethral obstruction secondary to the surgical treatment of an intramural ectopic ureter in a dog.Case: An 8-month-old female French bulldog with dysuria and urinary incontinence was seen at a private veterinary hospital in Jaboticabal, São Paulo. The patient had previously been diagnosed with an intramural ectopic ureter on the right side following imaging tests (ultrasound, computed tomography, and abdominal radiography, excretory urography) and had undergone neoureterostomy and closure of the intramural pathway approximately a year ago. Ultrasonographic examination showed dilation of the caudal portion of the ureter and hydroureter, which was suggestive of right ureteral stenosis. Computed tomography was also performed to evaluate the kidneys, ureters, and bladder; an increase in the diameter of the right ureter in its middle portion and close to the bladder triangle was observed. A new surgical intervention was indicated and performed. The ureteral route was identified in a region of the bladder trigone, incised, and probed with a urethral probe No. 04. The intramural course in the proximal urethra was identified and probed with a 16G epidural catheter. It was necessary to perform a neoureterostomy. A longitudinal incision (spatulation) of approximately 5 mm was made in the distal portion of the right ureter to increase the circumference of the anastomosis. The double J 4.7 French (Fr) catheter was inserted through the new ureter ostium into the bladder and advanced into the right kidney in a retrograde manner. Once the proximal end of the double J catheter reached the renal pelvis, the guidewire was withdrawn slowly to allow the catheter to bend in the areas of the renal pelvis and the trigone. The distal end of the double J catheter that extended beyond the bladder lumen was sectioned for better bladder closure. The patient underwent clinical evaluation and laboratory tests (complete blood count and serum creatinine concentration, urine test with bacteriological culture and susceptibility test) 2 weeks after the procedure and, subsequently, every 3 months. Ultrasonography of the urinary tract was performed every 2 months.Discussion: We used a double J catheter in the patient due to a previous obstruction of the ureter ostium after the first surgical procedure. In this way, complications such as postoperative obstructions due to ureteritis and ureteral constriction were avoided and ureteral anastomosis was facilitated. It has been reported that animals subjected to ureteral stent placement have high incidences of dysuria and urinary tract infection, and low incidences of stent migration and occlusion. In this case, no signs of occlusion or obstruction of the implant were identified, but there was a recurrence of urinary tract infections. These frequently cause urethral obstruction associated with the healing of the new ureteral ostium. Patient follow-up and findings associated with the long-term insertion of the double J catheter provide support for the clinical relevance of the present report.

Surgical management of ectopic ureters in dogs: Clinical outcome and prognostic factors for long-term continence.

To determine outcomes after surgical correction of ectopic ureters (EU) and identify prognostic factors for long-term continence. Retrospective study. Forty-seven dogs (36 females and 11 males). Medical records (1999-2016) of dogs with surgical correction of EU were reviewed. A continence score (1 = incontinent, 2 = sporadic incontinence, 3 = continent) was attributed preoperatively, at discharge, 1 month postoperatively, and at long-term evaluation. Twenty-eight dogs had unilateral and 19 dogs had bilateral EU (57 intramural and 9 extramural). Nineteen dogs had a pelvic bladder. Neoureterostomy with dissection (n = 50), ureteroneocystotomy (n = 9), or nephroureterectomy (n = 7) were performed. Thirty-three dogs were neutered: 32 before or during the surgery and 1 after surgery. Colposuspension was performed during surgical correction in 15 dogs. Adjuvant medical treatment improved postoperative continence scores. Median continence scores were greater at discharge (3), at 1 month postoperatively (3), and at long-term evaluation (3) than before surgery (1). At long-term evaluation (mean 46.1 months), a score of 1 was observed in 19%, a score of 2 in 7%, and a score of 3 in 74% of the dogs. Overall, good (score 2) to excellent (score 3) long-term outcome was achieved in 81% of dogs. Long-term continence was improved with medical treatment and neutering was not associated with an increased risk of recurrence of incontinence in this population of dogs.

Computed tomographic excretory urography features of intramural ectopic ureters in 10 dogs.

To describe the morphologic and morphometric computed tomographic excretory urography features of intramural ectopic ureters in dogs. Retrospective evaluation of computed tomographic excretory urography studies in 10 dogs with surgical and/or cystoscopically confirmed intramural ectopic ureters. All studies were assessed for ureteral ectopia, dilatation, tortuosity, ureterovesicular junction morphology and ureteral orifice location. A total of 14 intramural ectopic ureters were confirmed at surgery/cystoscopy with reviewers correctly identifying 100% (14/14). Abnormalities on computed tomographic excretory urography included ureteral dilatation (7), ureteral tortuosity (3), lack of a normal ureterovesicular junction (14), urethral ureteral orifice location (14) and lack of ureteral divergence (14). Lack of a normal ureterovesicular junction, a urethral-ureteral orifice location and lack of ureteral divergence are common computed tomographic excretory urography findings in dogs with intramural ectopic ureters. This technique requires further investigation to determine whether it might allow differentiation of intramural and extramural ectopic ureters.

Surgical Correction of Ectopic Ureter in Dogs

A Maltese (case 1) and a Labrador Retriever (case 2) presented with urinary incontinence. General conditions were good and screening tests, including a complete blood count, serum chemistry and radiography, were performed. Excretory urography was conducted, and fluoroscopy was performed for case 1 and computed tomography was performed for case 2. The dogs were diagnosed as right extramural ectopic ureter in case 1 and bilateral intramural ectopic ureter in case 2. We performed surgical corrections, including a neoureterocystostomy for extramural ectopic ureter and neoureterostomy for intramural ectopic ureter. After surgery, the dogs were catheterized with an indwelling catheter for 3 days. Urinary incontinence improved completely and the clinical outcomes were good. The choice of adequate surgical procedure is important for correcting ectopic ureters in canines.

Lack of usefulness of ureteral reconstruction with free bladder mucosa flap in dogs confirmed by microangiography.

BackgroundThere is a paucity of data addressing the blood supply in the surgically reconstructed ureter, and complete lack of microangiographic studies of the reconstructed ureter with the use of a free bladder mucosa flap. The present study evaluated the blood supply in the reconstructed dog ureter after a 5-centimeter segment resection, supplemented by a tube constructed from a free bladder mucosa flap.Material/MethodsFemale mongrel dogs (n=29) were used in this study. Under general anaesthesia, a 5-centimeter autologous free bladder mucosa flap was used to construct a tube, which was afterwards grafted to replace a 5-centimeter ureter resection. After a period of 3 months (n=2) and after 1 year (n=2), microangiography was performed to assess the revascularization of the grafted ureter.ResultsIn our study, we observed the continuity of the ureter, but the grafted reconstruction was narrowed by the cicatrization in about 86% (n=25) of cases. This resulted in the development of hydronephrosis, as described in previous publications. The ureteral wall was covered by a normal urothelium, but consisted of fibrous connective tissue, which failed to restore a regular (normal) coat. The reconstructed segment showed no smooth muscle cells. A few smooth monocytes were found only at the border with intact portions of the ureter. The microangiography performed at the end of the experiments showed no vascularization of the restored segment of the ureter.ConclusionsThe experiments showed a whole regeneration of urothelium in the transected and reanastomosed ureters. However, there was no regeneration of the muscular coat and a complete lack of revascularization.

Ectopic Ureters in Male Dogs: Review of 16 Clinical Cases (1999–2007)

Ureteral ectopia is a well-described cause of urinary incontinence in female dogs, but this condition has not been completely characterized in male dogs. Sixteen male dogs with ectopic ureters were evaluated between Jan 1999 and Mar 2007. Male dogs were similar to female dogs with ectopic ureters in terms of breed, presenting complaint, age of onset, and bilateral nature of the ectopia. Diagnosis was made by expert interpretation of imaging techniques such as excretory urography and contrast-enhanced computed tomography (CT). Overall, 11 of 13 dogs that had surgical correction of ectopic ureters were incontinent preoperatively. Urinary continence was restored in 82% of those dogs.

Ectopic Ureters in Dogs: Clinical Features, Surgical Techniques and Outcome

To compare clinical features of ectopic ureter (EU) in male and female dogs and outcome after neoureterostomy with resection restricted to the intravesical part of the ureter for intramural ectopic ureter (iEU) or of ureteroneocystostomy for extramural ectopic ureter (eEU). Retrospective case series. Female dogs (n = 26) with 32 iEU and 8 eEU; male dogs (n = 24) with 25 iEU and 18 eEU. Data were collected from medical records (1992-2008). Long-term follow-up information after surgical correction by modified neoureterostomy or ureteroneocystostomy was gathered by owner questionnaire. Median age at first occurrence of UI was significantly lower in females (<2 months) than in males with EU (8 months; P = 0.0015). Bilateral occurrence and an extramural course of the ureter were more common in males (n = 19 and n = 20, respectively) compared with females (14 and 12, respectively), but the outcome of surgical treatment was comparable in both genders. The prognosis after surgery is fair with a success rate of 72% and a complication rate of 26%. Resection of only the intravesicular ectopic ureter resulted in resolution of incontinence in a high percentage of dogs and thus is an acceptable alternative to removal of the entire ureteral remnant.

Evaluation of cystoscopic-guided laser ablation of intramural ectopic ureters in female dogs

To describe and evaluate the short- and long-term outcomes in female dogs after cystoscopic-guided laser ablation of ectopic ureters (CLA-EU). Prospective case series. 32 incontinent female dogs with intramural ectopic ureters. A diagnosis of intramural ectopic ureters was made via cystoscopy and fluoroscopy in all patients. Transurethral CLA-EU (via diode laser [n = 27] or Holmium:yttrium aluminum garnet laser [3]) was performed to relocate the ectopic ureteral orifice cranially into the urinary bladder. All vaginal anomalies were treated with the laser concurrently. Follow-up evaluation was standardized and included urinary continence scoring, serial bacteriologic culture of urine samples, and a follow-up cystoscopy 6 to 8 weeks after CLA-EU. Ectopic ureteral orifices of all dogs were initially located in the urethra. Eighteen of 30 dogs had bilateral ectopic ureters, and 12 had unilateral ectopic ureters. All dogs had other concurrent urinary anomalies. At the time of last follow-up (median, 2.7 years after CLA-EU, [range, 12 to 62 months]), 14 of 30 (47%) dogs did not require any additional treatments following CLA-EU to maintain urinary continence. For the 16 residually incontinent dogs, the addition of medical management, transurethral bulking-agent injection, or placement of a hydraulic occluder was effective in 3, 2, and 4 dogs, respectively, improving the overall urinary continence rate to 77% (23/30 dogs). One dog had evidence of polypoid cystitis at the neoureteral orifice 6 weeks after CLA-EU that was resolved at 3 months. CLA-EU provided an effective, safe, and minimally invasive alternative to surgery for intramural ectopic ureters in female dogs.

Cystoscopic diagnosis and treatment of ectopic ureters in female dogs: 16 cases (2005–2008)

To determine outcome of cystoscopic-guided transection for treatment of ectopic ureters in dogs. Retrospective case series. 16 female dogs. Medical records of dogs that underwent cystoscopic-guided transection of the membrane separating unilateral or bilateral ectopic ureters from the urethra and bladder between May 2005 and May 2008 were reviewed. Postoperative outcome was determined by use of telephone interviews conducted 1 to 36 months after the procedure. 4 dogs had complete resolution of urinary incontinence with cystoscopic-guided transection alone, an additional 5 dogs had complete resolution with a combination of cystoscopic-guided transection and phenylpropanolamine administration, and an additional 4 dogs had an improvement in urinary control, although urinary incontinence persisted. Outcome could not be assessed in the remaining 3 dogs because of collagen injections in the urethra at the time of ureteral transection (n = 2) or nephrectomy secondary to unilateral hydronephrosis (1). Results suggested that cystoscopic-guided transection may be an acceptable alternative to traditional surgical correction of ectopic ureter in dogs. Most complications associated with the cystoscopic procedure were minor and easily managed.

Amniotic stem cells repair ureteric defect: a study to evaluate the feasibility of amniotic membrane as a graft in surgical reconstruction

Amniotic membrane is considered a promising procedure as a graft in the field of ophthalmology and skin reconstruction. It has been shown to decrease inflammation, fibrosis, elicit no host immune reaction and also has antibiotic actions. Recently, the amnion has been shown to contain cells capable of plasticity. Therefore, we felt its application could be extended to include surgical reconstruction. We used ureteric reconstruction to study the feasibility of the amnion as a graft in these situations. We induced different degrees of injury in the ureter of dogs and reconstructed the defect with amniotic membrane. In addition, we also studied the effects of supplying the graft with a source of blood supply. The subjects were sacrificed after 6 weeks and histopathological examination showed impressive repair of the defect. The post reconstruction complications seen with present grafts were not seen with amniotic membrane. Therefore, amniotic membrane has produced noteworthy results and its potential should be further evaluated in order to be used as a cheap, readily available source of graft for the various surgical reconstruction procedures.

The ROMK potassium channel is present in mammalian urinary tract epithelia and muscle

There is increasing evidence that mammalian urinary tract epithelial cells utilize membrane channels and transporters to transport solutes across their apical (luminal) and basalateral membranes to modify solute concentrations in both cell and urine. This study investigates the expression, localization, and regulation of the ROMK (K(ir) 1.1) potassium channels in rat and dog ureter and bladder tissues. Immunoblots of homogenates of whole ureter, whole bladder, bladder epithelial cells, and bladder smooth muscle tissues in both rat and dog identified approximately 45- to 50-kDa bands characteristic of ROMK in all tissues. RT-PCR identified ROMK mRNA in these same tissues in both animal species. ROMK protein localized by immunocytochemistry was strongly expressed in the apical membranes of the large umbrella cells lining the bladder lumen and to a lesser extent in the cytoplasm of epithelial cells and smooth muscle cells in the rat bladder. ROMK protein and mRNA were also discovered in cardiac, striated, and smooth muscle in diverse organs. There was no difference in immunoblot expression of ROMK abundance in bladder homogenates (whole bladder, epithelial cell, or muscle cell) or ureteral homogenates between groups of rats fed high- or low-potassium diets. Although the functional role of ROMK in urinary tract epithelia and smooth muscle is unknown, ROMK may participate in the regulation of epithelial and smooth muscle cell volume and osmolality, in the dissipation of potassium leaked or diffused from urine across the epithelial cell apical membranes or tight junctions, and in net or bidirectional potassium transport across urinary tract epithelia.

Captopril reduces deposition of collagen in lamina propria and muscular layers of the bladder and ureter in neonatal dogs with partial urethral obstruction

It has been recognized that most boys with posterior urethral valve ablation have varying degrees of ureteral dilation and abnormal bladder function. It has been shown that deposition of collagen in the bladder layers increases the intravesical pressure that is transmitted to the pelvicalyceal system. The purpose of this study was to evaluate, using stereological methods, the effect of captopril on prevention of collagen formation in different layers of the ureter and bladder under conditions of partial urethral obstruction (PUO). PUO was induced in 10 neonatal dogs. These animals were then divided into two equal groups: the experimental group received captopril (35 mg/kg/day) and the positive control group received no treatment. After 6 weeks, the neonatal dogs underwent left nephroureterectomy and cystectomy. The ureter and bladder volumes, the volume fraction and absolute volume of the histological parameters of the ureter and bladder, the collagen content of the lamina propria, muscular and adventitial layers, and the muscle content of the muscular layer were estimated using stereological methods. The ureter and bladder volumes, the volumes of the layers including mucosa, lamina propria and muscular layer adventitia, the muscle content of the muscular layer and the collagen content of the adventitial layer did not show any significant differences between the groups. The collagen content (absolute volume) of lamina propria and muscular layer in the experimental group was lower than that in the positive control group for both the ureter and bladder. Administration of captopril decreases the collagen content of the lamina propria and muscular layer in the ureter and bladder of neonatal dogs with PUO.

Comparison between ureteral replacements using a transverse tubularized colonic tube or ileal ureter: experimental study in dogs

Introduction We report the comparison between ureteral replacements using a transverse tubularized colonic tube or ileal ureter in dogs. Materials and Methods Ten canines were studied. Four underwent ureteral substitution with an ileal ureter; 5 with a single transverse tubularized colonic tube and 1 with a double colonic transverse tubularized tube. The animals were observed for a predetermined interval of 30 days. At 30 days, the animals underwent an intravenous pyelogram, cystogram, urine analysis, and serum electrolyte sampling, and the kidney, ureteral conduit, and bladder were examined grossly and histologically. Results The pyelograms of both the ileal ureter and the transverse tubularized colonic tube showed prompt bilateral renal excretion. Grade 1 hydronephrosis was seen in 3 of 4 animals that received the ileal ureter and with 1 of 5 animals that received the colonic tube. Histological exam of the kidneys showed small focal areas of pyelonephritis in both groups without significant injury to the collecting tubules or glomeruli. Discussion The transverse tubularized colonic tube is an effective form of ureteral replacement in the animal model. The advantages of using the colon include its proximity to the ureters, the minimal mobilization needed, position outside the radiation portals, and the short colonic segment necessary.

First Prize: Ureteral Segmental Replacement Revisited

Long strictures of the proximal ureter are difficult to manage, and circumferential replacement with various natural and synthetic materials has been unsuccessful. We sought to use cultured autologous cells seeded onto graft material for proximal-ureteral replacement. Additionally, we wished to determine if urothelial cell-seeded de-epithelialized small bowel would generate adequate ureteral replacement. Three sets of experiments were performed. First, autologous pig-bladder smooth-muscle and urothelial cells were expanded in culture on large sheets of multilayer small-intestinal submucosa (SIS). These sheets were then tubularized and used to replace a 5-cm segment of proximal ureter in pigs. Second, autologous cells harvested from the bladders of Beagle dogs were cultured and seeded on porcine ureteral acellular matrix, which was used to replace a 3-cm segment of ureter in dogs. Segments were wrapped in omentum to enhance vascularity. Third, a de-epithelialized small-bowel segment seeded with autologous bladder-epithelial cells was transversally retubularized (Monti) into a 4-cm ureteral replacement. Follow-up studies consisted of retrograde pyelography, serum chemistry assays, hematoxylin/eosin studies, and immunohistopathologic examination using antibodies against alpha-smooth-muscle actin and pancytokeratin AE1-AE3. Coculture of urinary-tract cells on large segments of SIS failed to create adequate ureteral replacement. All grafts were contracted and stenotic, with complete obstruction of the ipsilateral renal unit. Similar results were seen in the Beagles. Despite clinical obstruction and gross contraction of the graft, a circumferential muscular ureteral wall lined with multilayer transitional epithelium was present. Urotheliumseeded de-epithelialized Monti bowel segments resulted in patent ureteral replacement without hydroureteronephrosis and with normal renal function, serum electrolytes, and acid-base balance. However, bowel mucosa fully regenerated, with multilayer transitional epithelium growing adluminally in continuity with the proximal and distal anastomotic sites. Seeding of ureteral grafts with autologous bladder cells does not promote success in two largeanimal models using different xenogenic acellular matrices. However, muscle and urothelium regeneration occurs with ureteral acellular matrix in the dog. Urothelium-seeded de-epithelialized Monti bowel segments may be an acceptable substitute for long proximal ureteral segments. Further technical refinements are required to replace the bowel mucosa completely with normal urothelium.