Benign Ureteral Obstruction Research Articles

Use of a subcutaneous ureteral bypass device for treatment of benign ureteral obstruction in cats: 174 ureters in 134 cats (2009-2015).

OBJECTIVE To determine outcomes of subcutaneous ureteral bypass (SUB) device placement for treatment of benign ureteral obstruction in cats. DESIGN Retrospective case series. ANIMALS 134 cats with SUB devices placed in 174 obstructed ureters during 144 hospitalizations. PROCEDURES Medical records of cats that underwent SUB device placement for treatment of benign ureteral obstruction between 2009 and 2015 were reviewed. The SUB device was placed by use of fluoroscopic and surgical methods. Signalment, history, diagnostic imaging results, postprocedural results, duration of hospitalization, complications, and short- and long-term outcomes were recorded. RESULTS Ureteral obstructions were caused by ureterolithiasis (114/174 [65.5%]), stricture (28/174 [16.1%]), both ureterolithiasis and stricture (29/174 [16.7%]), or pyonephrosis (1/174 [0.6%]); in 2 (1.1%) cats, the cause was not recorded. Fifty-two of the 134 (39%) cats had bilateral ureteral obstruction. At admission, 127 (95%) cats were azotemic. Median serum creatinine concentrations at admission and 3 months after SUB device placement were 6.6 and 2.6 mg/dL, respectively. Median renal pelvis diameters before and after the procedure were 9.2 and 1.5 mm, respectively. Postsurgical complications included device occlusion with blood clots (14/172 [8.1%]), device leakage (6/172 [3.5%]), and kinking of the device tubing (8/174 [4.6%]). Cats survived to hospital discharge after 135 of the 144 (94%) hospital admissions. The most common long-term complication was catheter mineralization (40/165 [24.2%]), which was documented a median of 463 days after device placement. A high postoperative serum ionized calcium concentration was significantly associated with SUB device occlusion. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that SUB device placement may be a viable option for treatment of cats with benign ureteral obstruction.

Fate of the Antegrade Ureteric Stent

Introduction Antegrade stents are commonly used to relieve malignant and benign ureteric obstruction. However, follow up of these patients often involves several specialties and the potential for delayed management and forgotten stents. This observational study reviews indications and outcomes of antegrade stent procedures at one university hospital to provide prognostic and quality improvement data. Patients and Methods A retrospective analysis of 152 antegrade stent procedures in 142 patients over a 27-month period was performed. Cohorts were studied according to underlying pathology, referring specialty and intended duration of stent placement. Measured outcomes were time to stent removal or stent exchange, death, forgotten stents and complications. Results The overall technical success rate of antegrade stent insertion was 98%. Follow-up data was available for 145 successful procedures in 138 patients. Malignancy (47%) and stone disease (35%) were the commonest indications. Overall, 43 patients (31%) died over a median follow up period of 2.2 years. 29 of 64 patients (45%) with malignancy died with stents in situ after a median interval of 3.5 months. Malignancy and unclear intended duration of stent placement were predictors of death with a stent in situ. Twelve patients (9%) had forgotten stents and a strong association with gynaecological malignancy was noted, which is felt to represent inadequate follow up of patients with non-urological pathology. Complications were reported in thirteen patients (9%), including ten cases of heavy stent encrustation and one malpositioned stent. Conclusions Prognostic factors should be considered in the management of patients stented for malignant obstruction, which is usually a marker of advanced disease. The hazards of inadequate follow up are highlighted, causing delays in stent removal and exchange, or the forgotten stent. Interventions are described to minimize these risks.

Comparative Evaluation of Nonprocedural Nephrostomy-Related Complications in Patients with Ureteric Obstruction due to Cancer versus Other Causes: Is the Protocol of Routine 3-month Nephrostomy Exchange Optimal for Both Disease Processes?

Abstract Purpose To evaluate nonprocedural percutaneous nephrostomy (PCN) complications and assess whether the protocol of routine 3-month exchange of PCN is optimal in patients with malignant ureteral obstruction (MUO) and benign ureteral obstruction (BUO). Materials and Methods Retrospective study of 103 patients with a mean age of 48 years (36 men, 67 women) who underwent PCN placement and subsequent PCN exchanges between January 2011 and January 2014 at the institution was conducted. Comparisons of the number of catheter days for those with routine exchange and emergency exchange due to tube obstruction, infection, and mechanical failures were made in patients with MUO and BUO. Results Of the 256 PCN exchange procedures, 139 were performed in the cancer cohort and 117 in the noncancer cohort. Complications requiring emergent exchanges were more common in cancer patients, particularly due to obstruction, which accounted for 57% of exchanges in MUO with a median onset of 50 days. In contrast, the majority of noncancer patients in this study did not require emergent exchange before 3 months. Routine exchanges accounted for 43% and 55% of exchanges in MUO and BUO, respectively. In both the groups, only a small proportion of emergent tube exchanges occurred beyond 105 days. Conclusion A routine 3-month nephrostomy exchange protocol may not be ideal for all patients. The optimal timing for exchange of nephrostomy appears to be earlier for patients with MUO compared with those with BUO. A prospective study is required to define an optimal policy for postprocedural nephrostomy tube care in both the cohorts.

Outcome of ureteral stent placement for treatment of benign ureteral obstruction in dogs: 44 cases (2010-2013).

OBJECTIVE To describe the technique and short- and long-term outcomes for dogs undergoing double-pigtail ureteral stent placement for treatment of benign ureteral obstruction. DESIGN Retrospective case series. ANIMALS 44 dogs (57 ureters). PROCEDURES Medical records of dogs that underwent ureteral stenting for treatment of benign ureteral obstruction between 2010 and 2013 were reviewed. Signal-ment, history, pertinent diagnostic imaging results, endourologic and post-procedural details, duration of hospitalization, complications, and outcome (short term, 7 to 30 days; long term, > 30 days) were recorded. Ureteral stent placement was performed endoscopically, surgically, or both, with fluoroscopic guidance. RESULTS 57 ureters (44 dogs) underwent stenting because of obstructive ureterolithiasis (n = 48 [84%]), stricture (5 [9%]), or both (4 [7%]). Endoscopic or surgical techniques were successful for stent placement in 45 of 55 and 12 of 12 ureters (34/42 and 10/10 dogs), respectively. Median hospitalization time was 1 day. Median creatinine concentration was 2 mg/dL prior to stenting and 1.3 mg/dL 3 months after the procedure. Urinary tract infections were present in 26 of 44 (59%) dogs prior to stenting and in 11 of 43 dogs (26%) after stenting. One of the 44 (2%) dogs died after undergoing stenting, but the cause of death was not related to the procedure. Median follow-up time was 1,158 days (range, 3 to > 1,555 days), with 30 of 44 dogs alive at the time of last follow-up. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that ureteral stenting may be a viable option for first-line treatment of dogs with benign ureteral obstruction. However, patients should be monitored for urinary tract infection following stenting.

3:00 PMAbstract No. 322 - Percutaneous nephrostomy (PCN) exchanges in benign ureteric obstruction: analysis of clinical outcomes and cost

3:00 PMAbstract No. 322 - Percutaneous nephrostomy (PCN) exchanges in benign ureteric obstruction: analysis of clinical outcomes and cost

Outcome in cats with benign ureteral obstructions treated by means of ureteral stenting versus ureterotomy.

OBJECTIVE To evaluate the outcome for cats with benign ureteral obstructions treated by means of ureteral stenting and to compare the outcome for these cats with outcome for a historical cohort of cats treated by means of ureterotomy only. DESIGN Prospective study with historical cohort. ANIMALS 62 client-owned cats with benign ureteral obstructions, including 26 cats treated with ureteral stenting and 36 cats previously treated with ureterotomy. PROCEDURES Data were recorded prospectively (ureteral stent cases) or collected retrospectively from the medical records (ureterotomy cases), and results were compared. RESULTS Cats treated with ureteral stents had significantly greater decreases in BUN and serum creatinine concentrations 1 day after surgery and at hospital discharge, compared with values for cats that underwent ureterotomy. Six cats in the ureteral stent group developed abdominal effusion after surgery, and cats in this group were significantly more likely to develop abdominal effusion when a ureterotomy was performed than when it was not. Cats that developed abdominal effusion after surgery were significantly less likely to survive to hospital discharge. Cats that underwent ureteral stenting were significantly more likely to have resolution of azotemia prior to hospital discharge than were cats that underwent ureterotomy alone. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that cats with benign ureteral obstructions treated with ureteral stenting were more likely to have resolution of azotemia prior to hospital discharge, compared with cats undergoing ureterotomy alone. Results of ureteral stenting were encouraging, but further investigation is warranted.

Application of resonance metallic stents for benign and malignant ureteral obstruction: long-term follow-up

Application of resonance metallic stents for benign and malignant ureteral obstruction: long-term follow-up

Clinical presentation and outcome of cats with circumcaval ureters associated with a ureteral obstruction.

BackgroundCircumcaval ureters (CU) are a rare embryological malformation resulting in ventral displacement of the caudal vena cava, which crosses the ureter, potentially causing a ureteral stricture.ObjectivesTo evaluate cats with obstructed CU(s) and report the presenting signs, diagnostics, treatment(s), and outcomes. Cats with obstructed CU(s) were compared to ureterally obstructed cats without CU(s).Animals193 cats; 22 circumcaval obstructed (Group 1); 106 non‐circumcaval obstructed (Group 2); 65 non‐obstructed necropsy cases (Group 3).MethodsRetrospective study, review of medical records for cats treated for benign ureteral obstructions from AMC and University of Pennsylvania between 2009 and 2013. Inclusion criteria: surgical treatment of benign ureteral obstruction, complete medical record including radiographic, ultrasonographic, biochemistry, and surgical findings.ResultsSeventeen percent (22/128) of obstructed cats had a CU (80% right‐sided) compared to 14% (9/65) non‐obstructed necropsy cats (89% right‐sided). Clinical presentation, radiographic findings, and creatinine were not statistically different between Groups 1 and 2. Strictures were a statistically more common (40%) cause of ureteral obstruction in Group 1 compared to Group 2 (17%) (P = .01). The MST for Groups 1 and 2 after ureteral decompression was 923 and 762 days, respectively (P = .62), with the MST for death secondary to kidney disease in both groups being >1,442 days. Re‐obstruction was the most common complication in Group 1 (24%) occurring more commonly in ureters of cats treated with a ureteral stent(s) (44%) compared to the subcutaneous ureteral bypass (SUB) device (8%) (P = .01).Conclusions and Clinical ImportanceUreteral obstructions in cats with a CU(s) have a similar outcome to those cats with a ureteral obstruction and normal ureteral anatomy. Long‐term prognosis is good for benign ureteral obstructions treated with a double pigtail stent or a SUB device. The SUB device re‐obstructed less commonly than the ureteral stent, especially when a ureteral stricture was present.

Technical and clinical outcomes of ureteral stenting in cats with benign ureteral obstruction: 69 cases (2006–2010)

OBJECTIVE--To evaluate the technical, short-term, and long-term outcomes in cats with benign ureteral obstructions treated by means of double-pigtail ureteral stent placement. DESIGN--Retrospective case series. ANIMALS--69 cats (79 ureters). PROCEDURES--The diagnosis of benign ureteral obstruction was made via abdominal ultrasonography, radiography, and ureteropyelography. Ureteral stent placement was attempted endoscopically, surgically, or both, with fluoroscopic guidance. The medical records were reviewed for pre-, intra-, and postoperative data; complications; and outcome. RESULTS--69 cats (79 ureters) had stent placement attempted for various causes: ureterolithiasis (56/79 [71%]), stricture (10/79 [13%]), both ureterolithiasis and stricture (12/79 [15%]), or a purulent plug (1/79 [1%]). Stent placement was successful in 75 of 79 ureters (95%). Median number of stones per ureter was 4 (range, 0 to > 50), and 67 of 79 (85%) had concurrent nephrolithiasis. Preoperative azotemia was present in 95% (66/69) of cats (median creatinine concentration, 5.3 mg/dL [range, 1.1 to 25.8 mg/dL]), and 71% (49/69) remained azotemic (median, 2.1 mg/dL [range, 1.0 to 11.8 mg/dL]) after successful surgery. Procedure-related, postoperative (< 7 days), short-term (7 to 30 days), and long-term (> 30 days) complications occurred in 8.7% (6/69; 7/79 ureters), 9.1% (6/66), 9.8% (6/61), and 33% (20/60) of cats, respectively; most of these complications were minor and associated with intermittent dysuria or the need for ureteral stent exchange. The perioperative mortality rate was 7.5% (5/69), and no deaths were procedure related. The median survival time was 498 days (range, 2 to > 1,278 days). For patients with a renal cause of death, median survival time was > 1,262 days, with only 14 of 66 cats (21%) dying of chronic kidney disease. Nineteen (27%) cats needed a stent exchange (stricture in-growth [n = 10], migration [4], ureteritis [2], dysuria [2], pyelonephritis [1], or reflux [1]). No patient died of the procedure or recurrent ureteral obstruction. CONCLUSIONS AND CLINICAL RELEVANCE--Results of the present study indicated that ureteral stenting is an effective treatment for benign ureteral obstructions in cats regardless of obstructive location, cause, or stone number. The perioperative morbidity and mortality rates were lower than those reported with traditional ureteral surgery. The short- and long-term complications were typically minor but may necessitate stent exchange or use of an alternative device, particularly with ureteral strictures. The prognosis for feline ureteral obstructions after ureteral stenting could be considered good when the procedure is performed by trained specialists.

Would the Indwelling Internal Ureteral Stent Influence Renal Function Despite Relief of Benign Ureteral Obstruction?

To assess the effect of internal ureteral stents (IUS) on renal function (RF) and to determine factors associated with the RF changes. Between February 2009 and September 2012, 103 patients with bilateral or IUS in a solitary kidney were retrospectively analyzed. The estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration Equation (CKD-EPI). It was calculated from serum creatinine after adequate relief of obstruction (baseline) and at last follow-up. Deterioration of eGFR was considered if the last eGFR declined by >20% from the baseline value. Predictors of RF changes were detected using univariate and multivariate binary logistic regression analyses. The mean patients' age was 54±14 years with males constituting 71.4% of the study population. During follow-up after IUS fixation, the median eGFR has declined from 50.6 mL/min/1.73 m(2) at baseline to 25 mL/min/1.73 m(2) at time of last follow-up (p<0.0001). Fifty-two (50.5%) patients experienced decline in their RF by >20% of baseline value. On multivariate analysis, positive urine culture (odds ratio [OR]: 3; p=0.026), baseline eGFR <60 mL/min (OR: 3.6; p=0.011), and extraluminal obstruction (OR: 2.9; p=0.035) were independent predictors of RF deterioration. One half of patients with IUS lasting more than 3 months experienced RF deterioration during follow-up. This decline was significantly associated with positive urine cultures, presence of CKD, and extraluminal obstruction. All efforts should be exerted for active treatment of associated urinary tract infection and active follow-up of RF.

Tandem Ureteral Stents for the Decompression of Malignant and Benign Obstructive Uropathy

To evaluate the utility of two ipsilateral ureteral stents placed for benign and malignant ureteral obstruction. We performed a retrospective analysis of all cases of tandem ureteral stent (TUS) insertion at our institution from July 2007 through January 2013. Student t, Fisher exact, and log-rank test were used. TUS insertion or exchange was performed in 187 cases. There were 66 patients (75 renal units) who underwent successful TUS insertion. Malignant ureteral obstruction (MUO) was the cause for obstruction in 39 renal units (34 patients) vs benign ureteral obstruction (BUO) in 36 renal units (32 patients). Four patients with BUO and 15 patients with MUO underwent stent exchanges at a mean 145 and 128 days, respectively. Serum creatinine levels were stable poststent placement (P=0.4). Degree of hydronephrosis improved (paired t test P<0.03) after stent placement for both benign and malignant cohorts. TUS placement was noted to fail (flank pain with worsening hydronephrosis or increasing creatinine level) in five renal units with MUO (12.8%) and none with BUO. Stent failure (either conventional or TUS) suggested worsening survival in those with MUO. Median survival for those with MUO and a history of stent failure (10 of 14 died, 71%) was 66 days compared with 432 days for those without a history of stent failure (8 of 20 died, 40%) (log-rank test P=0.007). Our experience with the TUS, the largest to date, demonstrated that they are highly successful in both benign and malignant causes of obstruction, comparing favorably with metallic ureteral stents. Stent failure may be predictive for shorter survival.

Metal Ureteral Stent for Benign and Malignant Ureteral Obstruction

Metal ureteral stents are a relatively new version of a device with a long history of relieving ureteral obstruction. Metal stents are effective for relieving ureteral obstruction but success regarding patient tolerability has been variable. We present our single institution experience with long-term metal ureteral stent placement. The charts of patients undergoing metal ureteral stent placement for chronic ureteral obstruction were reviewed. Data collected included patient age, gender, diagnosis/cause of obstruction, laterality, duration of indwelling metal stent, number of routine metal stent changes, complications and early discontinuations or stent changes. A total of 23 patients underwent placement of metal ureteral stents between February 2008 and September 2010. Bilateral stents were placed in 5 patients and 9 underwent a yearly metal stent exchange for a total of 42 ureteral units treated with metal ureteral stents. All metal stents were placed to relieve ureteral obstruction due to ureteral stricture, ureteropelvic junction obstruction, retroperitoneal fibrosis or extrinsic malignant obstruction. There were 3 metal stent failures in 2 patients with malignant ureteral obstruction. There were no complications, or early discontinuations or changes due to adverse symptoms, patient dissatisfaction, worsening renal function or progressive hydronephrosis. Metal ureteral stents are effective for benign and malignant ureteral obstruction in the absence of urolithiasis. Good tolerability and annual stent exchange make metal stents an appealing alternative for patients with chronic ureteral obstruction treated with indwelling ureteral stents.

Predictors of morbidity in patients with indwelling ureteric stents: results of a prospective study using the validated Ureteric Stent Symptoms Questionnaire

To assess the predictors of morbidity in patients with indwelling ureteric stents using a validated questionnaire. Eighty-six consecutive patients with indwelling double-J ureteric stent of different length and size enrolled at an Italian tertiary academic centre were prospectively evaluated with the Italian-validated Ureteric Stent Symptoms Questionnaire (USSQ), which explores the stent-related symptoms in six domains. Ureteric stents were placed for benign ureteric obstruction or after uncomplicated ureterorenoscopy, and were all removed after 28 days. The questionnaire was administered on days 7 and 28 after stent placement and on day 28 after removal. A plain abdominal X-ray was performed on days 7 and 28 after placement to determine stent location. Univariable and multivariable analyses tested the association of patient age, sex and body mass index (BMI), and stent side, length, calibre and distal loop location, with the index score of the various domains on days 7 and 28. All patients completed the study. At multivariable analysis, on day 7, sex, BMI and stent calibre were significantly associated with one domain (general health, body pain and work performance, respectively), while location of stent distal loop was significantly associated with five domains (urinary symptoms, body pain, general health, work performanc, and sexual matters). On day 28, body mass index was significantly associated with two domains (body pain and general health), while location of stent distal loop remained significantly associated with the same five domains (urinary symptoms, body pain, general health, work performance and sexual matters). Location of stent distal loop with respect to midline had the strongest association with most domains of the USSQ on both days 7 and 28 after stent placement. The visualization of stent distal loop crossing the midline may therefore identify patients at higher risk of post-procedural morbidity requiring early management.

Updates on the use of ureteral stents: focus on the Resonance&amp;reg; stent

The Resonance® metallic ureteral stent is one of the latest additions to the urologist’s armamentarium in managing ureteral obstruction. One advantage of this stent over traditional polymer-based stents is resistance to encrustation with stone material, which allows longer dwell times and less frequent exchange procedures. Although exchanging a metallic stent is slightly more complicated than exchanging a polymer stent, the fluoroscopic techniques required are familiar to most urologists. The Resonance stent is also more resistant to compression by external forces, potentially allowing greater applicability in patients with metastatic cancer. Furthermore, the use of this stent in patients with benign ureteral obstruction is shown to be associated with significant cost reduction. Clinical studies on the use of this stent are accumulating and the results are mixed, although Level 1 evidence is lacking. In this article we present a comprehensive review of the available literature on the Resonance metallic ureteral stent.

Application of resonance metallic stents for ureteral obstruction

• To determine the effectiveness of the Resonance ureteral stent and clarify the risk factors that lead to stent failure. In the present study, we review our clinical experiences using Resonance stent in treating malignant and benign ureteral obstruction. • Nineteen patients with extrinsic malignant ureteral obstruction (n= 15) and benign stricture (n= 4) were retrospectively evaluated. • All patients had received Resonance stent insertion through antegrade or cystoscopic retrograde approaches. The pre-insertion and follow-up interventions included image studies and biochemical tests. The insertion success rate, obstruction patency rate and complications were reviewed. • For categorical variables, the chi-square test and Fisher's exact test were carried out to determine associations between variables. • The technical success rate of stent insertion was 84.6%. The mean follow-up was 5 months (range 1-10.5 months). • Five stents failed to alleviate the obstruction, and the patency rate was 77.3% (17/22). • Patients who had had previous radiation therapy had a lower ureter patency rate in comparison with non-radiation patients (50% vs 92.3% respectively, P= 0.039). • The 6- and 9-month patency rates were 81.0% with 11 stents and 27.0% with 3 stents, respectively. • The results of the present study demonstrated that malignant or benign ureteral obstruction could be treated safely and sufficiently with the Resonance metallic stent. • Careful patient selection is critical to achieve successful results. • For malignant ureteral obstruction, previous radiation therapy is a risk factor for stent failure.

Multicenter Experience with Metallic Ureteral Stents for Malignant and Chronic Benign Ureteral Obstruction

A new coil-based metallic ureteral stent offers greater radial strength with longer indwelling time compared with plastic stents. This multicenter retrospective study reviews the clinical experience with this stent for malignant or benign chronic ureteral obstruction. Patients had stent placement in a retrograde fashion. We analyzed preplacement and postplacement renal imaging to determine degree of hydronephrosis. Stent encrustation was determined by either visual inspection at the time of stent change or plain abdominal radiography. Preoperative and follow-up serum creatinine values were compared for each patient. A total of 76 stents in 59 renal units (40 patients) were successfully placed. Creatinine value follow-up on 54 renal units showed 20 (37%) units to have stable, 15 (28%) improved, and 19 (35%) with worsening values. No stent showed encrustation on plain radiography despite it being seen on two during direct visualization. Three stents needed operative removal with either percutaneous nephrolithotomy or cystolitholapaxy. Fifteen of 41 (37%) metallic stents placed because of an obstructed plastic stent also became obstructed. At last follow-up, 6 of 40 patients were kept from nephrostomy tubes because of the metallic stent. Metallic stents are a viable alternative to nephrostomy tubes in patients in whom conventional stents fail because of malignant obstruction, but patients need to be followed closely. Stent encrustation that resulted in retained stents was poorly visualized on plain radiography. Patients still remain at risk for obstruction, urinary tract infections, and lower urinary tract symptoms from the metallic stent.

Metallic Ureteral Stents: A Cost-Effective Method of Managing Benign Upper Tract Obstruction

The management of patients with upper urinary tract obstruction who are not candidates for definitive reconstruction often presents a challenge. We report our initial experience with the Resonance (Cook Urological, Spencer, IN) metallic ureteral stent for the management of benign ureteral obstruction and present a comparative cost analysis of metallic to standard polymer stent use. Data were retrospectively gathered on all patients undergoing metallic ureteral stent placement for benign causes from July 2007 to February 2009. Baseline demographics, previous method of drainage, pre- and postoperative creatinine levels, procedural complications, stent-related side effects, and metallic stent dwell time were recorded. The cost of stent maintenance for polymer and metallic stents for a 12-month interval was calculated for each patient. Fifteen stents were placed in 13 patients to manage obstruction due to a variety of benign etiologies. Metallic stents provided adequate drainage in 12/13 patients, but were discontinued prematurely in 3 patients (2 for voiding symptoms, 1 for hematuria). Eight patients had their metallic stents changed after a mean time of 11.6 months, with no encrustation. The yearly cost associated with polymer and metallic stent use was $23,999 and $11,183, respectively. This amounted to a $10,394 annual cost reduction (43%) for each patient. Metallic ureteral stents provide effective upper tract drainage for the majority of patients with benign upper tract obstruction, with significant cost benefit, largely because of the shorter exchange interval.

Ureteral Obstruction: Is the Full Metallic Double-Pigtail Stent the Way to Go?

BackgroundThe Resonance metallic ureteral stent (Cook Medical, Bloomington, Indiana, USA) has been introduced for the management of extrinsic-etiology ureteral obstruction for time periods up to 12 mo. ObjectiveThe current study aims to determine short- and medium-term effectiveness of the Resonance stent in malignant and benign ureteral obstruction. Design, setting, and participantsIn total, 50 patients with extrinsic malignant obstruction (n=25), benign ureteral obstruction (n=18), and previously obstructed mesh metal stents (n=7) were prospectively evaluated. InterventionAll patients were treated by Resonance stent insertion. Twenty stents were inserted in antegrade fashion, and the remaining stents were inserted in a retrograde approach. No patient dropped out of the study. The follow-up evaluation included biochemical and imaging modalities. MeasurementsWe evaluated the technical success rate, stricture patency rate, complications, and the presence and type of encrustation. Results and limitationsThe technical success rate of transversal and stenting of the strictures was 100%. In 19 patients, balloon dilatation was performed prior to stenting. The mean follow-up period was 8.5 mo. The stricture patency rate in patients with extrinsic malignant ureteral obstruction was 100% and in patients with benign ureteral obstruction 44%. Failure of Resonance stents in all cases of obstructed metal stents was observed shortly after the procedure (2–12 d). In nine cases, stent exchange was demanding. Encrustation was present in 12 out of 54 stents. ConclusionsThe Resonance stent provides safe and sufficient management of malignant extrinsic ureteral obstruction. Resonance stent use in benign disease needs further evaluation, considering the untoward results of the present study.

Application of Self-Expandable Metal Stents for Ureteroileal Anastomotic Strictures: Long-Term Results

We report our long-term experience with the management of benign ureteroileal anastomotic strictures using self-expandable metal stents. A total of 16 male and 2 female patients with a mean+/-SD age of 72+/-7 years (range 66 to 78) with benign fibrotic strictures at the site of ureteroileal anastomosis underwent implantation of self-expandable metal stents with a nominal diameter of 6 to 8 mm. A total of 24 ureteroileal conduits were treated. The external nephrostomy tubes were removed after fluoroscopic validation of ureteral patency. Patients were followed with blood biochemistry, ultrasonography, urography and/or virtual endoscopy. Retrograde external-internal catheter insertion through the cutaneous stoma was performed in cases of recalcitrant stricture. The technical success rate of ureteroileal stricture crossing and stenting was 100% (24 of 24 cases). Mean followup was 21 months (range 7 to 50). The clinical success rate during the immediate post-stenting period was 70.8% (17 of 24 cases). The 1 and 4-year primary patency rates were 37.8% and 22.7%, respectively. Secondary interventions included repeat balloon dilation in 15 ureters, of which 8 also underwent subsequent coaxial stent placement. The 1 and 4-year secondary patency rates were 64.8% and 56.7%, respectively. Except in 2 patients who died external-internal Double-J catheters continued to be inserted retrograde in 6 ureteroileal conduits. They are periodically exchanged to prevent mucous inspissation and stent encrustation. Metal stents served as the definitive treatment for stricture in more than half of the cases, whereas in the remainder the stents allowed the uncomplicated and regular exchange of Double-J catheters in retrograde fashion. This combined, less invasive treatment for ureteroileal anastomotic strictures may help patients avoid surgical revision and preserve quality of life.

Percutaneous Wallstent Implantation to Rescue Failed Ureteropyelostomy for Massive Ureteral Necrosis after Renal Transplantation

A 44-year-old woman with end-stage renal disease underwent cadaver renal transplantation at another hospital. Two weeks after surgery, much clear fluid emerged from the operative wound. The patient visited our hospital and abdominal ultrasonography identified a fluid collection near the right perivesical space. A percutaneous nephrostomy was performed for urinary diversion. Antegrade pyelography showed renal pelvis distortion, an irregular surface along the entire ureter, and a severe stricture near the lower ureter, suggestive of massive ureteral necrosis of the graft. The initial treatment comprised resection of the necrotic ureter followed by an end-to-side pyeloureterostomy to join the graft renal pelvis to the middle portion of the ipsilateral native ureter. Although the postoperative period was initially unremarkable, delayed urine extravasation was noted on the fifth postoperative day. Antegrade pyelography revealed a 0.5-cm disruption gap between the graft renal pelvis and the native ureter (Fig. 1A). After discussion of the available treatment options with the patient, a metallic stent 6 mm in diameter and 30 mm in length (Wallstent; Schneider, Zurich, Switzerland) was inserted via a percutaneous antegrade approach to bridge the defect between the native ureter and graft renal pelvis. Subsequent recovery was uneventful, and antegrade pyelography showed that urine was no longer leaking from the disruption gap. The Wallstent was found to have remained in a good position (Fig. 1B) and the collecting system was patent without evidence of stone formation on three-dimensional computed tomography 10 months later. Over a 5-year follow-up period, the patient had stable renal function without sequelae.FIGURE 1.: (A) Antegrade pyelography showed a 0.5-cm ureteral disruption gap at the ureteropyelostomy anastomosis (black arrow) between the graft renal pelvis and native ureter (hollow arrow). (B) A metallic Wallstent (large arrow) was used to bridge the native ureter to the renal pelvis of the graft kidney. The small arrow indicates refluxing contrast medium in the upper portion of the right native ureter.With a reported incidence of 2.1%, ureteral necrosis is relatively uncommon after renal transplantation (1). Different techniques have been considered to repair the various types of ureteral injury. Pyeloureterostomy joining the graft pelvis to the distal portion of the native ureter is the preferred method when dealing with massive ureteral necrosis (1). Few reports have addressed further management when pyeloureterostomy fails. Antegrade or retrograde endourologic stent implantation may provide temporary relief of ureteral obstruction but can potentially lead to complications like stent encrustation or repeated urinary tract infections. Artificial ureteral replacement was successfully used in three patients with renal transplant ureteral necrosis in 1998 by Desgrandchamps et al. (2), who employed a minimally invasive technique originally described for the palliation of malignant ureteral obstructions. Based on a mean of 32-months of follow-up, the investigators concluded that the subcutaneous bypass is a simple and safe procedure, although late encrustation of the prosthesis remains a major concern. In our case, repeat operation of the disrupted pyeloureterostomy would have been difficult as a result of local inflammation. Likewise, a subcutaneous artificial ureteral replacement may not prevent persistent urine leakage from the disrupted anastomosis. Metal stents (e.g. Wallstents) are routinely used in the cardiovascular and biliary systems (3, 4) and have been deployed for malignant and benign ureteral obstruction with excellent results (5–7). The use of the technique presented in this case was able to bridge the defect caused by the disrupted pyeloureterostomy anastomosis, thereby avoiding further open surgery, with its associated morbidity. Because the presence of this new adynamic ureteral segment may cause morbidity such as stone formation in the future, regular follow-up of renal function and collecting system patency will remain crucial components in the ongoing management of this patient. Victor Chia-Hsiang Lin Division of Urology Department of Surgery E-Da HospitalI-Shou University Kaoshiung, Taiwan Alex Chien-Hwa Liao Division of Urology Department of Surgery Chi-Mei Medical Center Tainan, Taiwan Li-Ching Chang Division of Urology Department of Surgery E-Da HospitalI-Shou University Kaoshiung, Taiwan Wen-Sheng Tzeng Department of Radiology Chi-Mei Medical Center Tainan, Taiwan