Extrinsic Ureteral Compression Research Articles

Insuficiência renal crônica como manifestação inicial de hemangioendotelioma pélvico

Hemangioendothelioma is a rare vascular tumor whose etiology has not yet been de?ned. Currently, it is known to affect different sites, such as the abdominal-pelvic cavity. It is also known to present intermediate characteristics to hemangioma and angiosarcoma. In recent studies, 50-76% of patients are asymptomatic. Surgical treatment is indicated in most cases. The authors present a case of hemangioendothelioma with pelvic involvement and initial presentation as acute renal failure due to extrinsic ureteral compression, treated surgically, with histopathological diagnosis of hemangioendothelioma and recurrence after one year of the initial treatment presenting a histologically different form. This case illustrates a rare cause of lower urinary tract symptoms (LUTS), obstructive uropathy and acute renal failure and the appearance of two different tumors within a year, in line with the genetic/immunological factor in its genesis.

Use of a shaving technique for surgical management of partial ureteral obstruction due to endometriosis

To illustrate the surgical management of advanced endometriosis causing extrinsic ureteral compression. Video description of the case, demonstration of the surgical technique, reevaluation at 14-year follow-up, and review of urogenital endometriosis. Patient provided consent for the video recording and publication. This surgical report with no identifying patient data was exempt from Institutional Review Board approval. Tertiary referral center. A 42-year-old nulligravida with a known history of endometriosis presented with persistent pelvic pain and no other specific symptoms. She had previously undergone a diagnostic laparoscopy demonstrating advanced endometriosis involving multiple organs, including the urinary tract. She was referred to us for further surgical management. Preoperative intravenous pyelogram showed partial obstruction and constriction of a long portion of the midpelvic and distal left ureter with proximal hydroureter, consistent with extrinsic ureteral compression. The patient underwent operative video laparoscopy using a multipuncture technique, with enterolysis, extensive left ureterolysis, shaving of periureteral constrictive fibrosis and endometriosis, cystoscopy, and placement of left ureteral stent. There was extensive endometriosis and fibrotic adhesions involving the left pelvic sidewall. Proximal hydroureter was noted to the pelvic inlet secondary to severe periureteral fibrosis from the pelvic brim to the bladder meatus, with significant narrowing of the pelvic ureter. The endometriosis was resected using hydrodissection and shaving with a carbon dioxide laser. Histopathologic evaluation of the resection specimens confirmed endometriosis. An intravenous pyelogram performed 4 weeks postoperatively revealed ureteral patency and resolving hydroureter, and her ureteral stent was removed. Annual renal ultrasounds for the subsequent 2 years were normal. Fourteen years later, she remained asymptomatic on no suppressive treatment. A follow-up intravenous pyelogram was performed and showed a normal urinary tract with bilateral ureteral patency and no recurrent strictures or hydroureter. In selected cases, conservative shaving of periureteral fibrotic endometriosis avoids ureteral resection and has acceptable outcomes.

The Impact of Ureteral Deformation and External Ureteral Pressure on Stent Failure in Extrinsic Ureteral Obstruction: An In Vitro Experimental Study.

Background and Purpose: Extrinsic ureteral obstruction is caused frequently by pelvic malignancies or metastatic lymphadenopathy, necessitating renal drainage with ureteral stents to prevent renal failure and kidney damage. Understanding the nature of stent behavior under deformation and realistic external pressures may assist in evaluation of stent performance. Few published studies have investigated the flow and mechanical properties of stents within ureters, and none has considered the effects of deformation and compression on flow in realistic, in vitro, ureter-stent systems. The purpose of this work was to determine whether or not stent failure is due only to stent compression and deformation in the presence of extrinsic obstruction. Methods: We developed an in vitro ureter-stent experimental setup, using latex tubing to simulate a flexible ureter connecting a renal unit and a bladder side. We examined flow behavior in three stents (4.8F, 6F, 7F). The ureter-stent configuration was varied, simulating four levels of deformation (0°, 20°, 40°, 60°) and then simulating different external compressive forces on a stented ureter with 40° deformation. A constant, realistic fluid flow was applied through the ureter-stent configurations, and pressure fluctuations in the renal unit were monitored. Results: Deformation alone on four different levels (0°, 20°, 40°, 60°) has essentially no influence on fluid flow and renal pressure variation. Under increasing external compressive forces of 500, 1000, 2000, and up to 5000 g at 40° deformation, no effect on fluid flow and pressure within the renal unit was noted for the 6F and 7F stents. The only exception was for the 4.8F stent, which demonstrated complete failure at compressive forces near 4000 g. Conclusions: Neither realistic extrinsic ureteral compression forces nor ureteral deformation explain the high frequency of stent failure in extrinsic ureteral obstruction. Other factors such as urine composition may be a major contributor to stent failure.

Office stent placement under local anesthesia is a safe and efficient procedure for the management of multiple ureteral disorders

ObjectiveTo assess the outcomes of ureteral stent placement under local anesthesia for the management of multiple ureteral disorders. MethodsRetrospective study of 45 consecutive ureteral stents placed under local anesthesia from January 2015 to July 2016. Inclusion criteria were hemodynamically stable patients with urinary obstruction, urinary fistula or for prophylactic ureteral localization during surgery. Five minutes before the procedure, 10ml of lidocaine gel and 50ml of lidocaine solution were instilled in the bladder. A 4.8Fr ureteral stent was placed using a 15.5Fr flexible cystoscope under fluoroscopic control. Characteristics of procedures and outcomes were analyzed. ResultsA total of 45 procedures (33 placement, 12 replacements) were attempted in 37 patients, of which 40 (89%) were successful. There were 10 male (27%) and 27 female patients (73%) with a mean age of 58.6 years (±17.5). Main indications for stent placement were stones (37.8%), extrinsic ureteral compression (28.9%) and surgery ureteral localization (22.2%). The reasons for failing to complete a procedure were the inability to pass the guidewire/stent in 4 cases (8.8%) or to identify the ureteral orifice in 1 (2.2%). Postoperative complications occurred in 8 patients (17.8%) (7 Clavien I, 1 Clavien IIIa). No procedure was prematurely terminated due to pain. Statistical analysis did not find significant successful predictors. The outpatient setting provided a fourfold cost decrease. ConclusionsUreteral stent placement can be safely and effectively performed under local anesthesia in the office cystoscopy room. This procedure could free operating room time, reduce costs and minimize side effects of general anesthesia.

La colocación de catéteres doble J con anestesia local en régimen ambulatorio es un procedimiento seguro y eficiente para el manejo de distintas patologías ureterales

ObjectiveTo assess the outcomes of ureteral stent placement under local anesthesia for the management of multiple ureteral disorders. MethodsRetrospective study of 45 consecutive ureteral stents placed under local anesthesia from January 2015 to July 2016. Inclusion criteria were hemodynamically stable patients with urinary obstruction, urinary fistula or for prophylactic ureteral localization during surgery. Five minutes before the procedure, 10ml of lidocaine gel and 50ml of lidocaine solution were instilled in the bladder. A 4.8Fr ureteral stent was placed using a 15.5Fr flexible cystoscope under fluoroscopic control. Characteristics of procedures and outcomes were analysed. ResultsA total of 45 procedures (33 placement, 12 replacements) were attempted in 37 patients, of which 40 (89%) were successful. There were 10 male (27%) and 27 female patients (73%) with a mean age of 58.6 years (±17.5). Main indications for stent placement were stones (37.8%), extrinsic ureteral compression (28.9%) and surgery ureteral localization (22.2%). The reasons for failing to complete a procedure were the inability to pass the guidewire/stent in 4 cases (8.8%) or to identify the ureteral orifice in 1 (2.2%). Postoperative complications occurred in 8 patients (17.8%) (7 Clavien I, 1 Clavien IIIa). No procedure was prematurely terminated due to pain. Statistical analysis did not find significant successful predictors. The outpatient setting provided a fourfold cost decrease. ConclusionsUreteral stent placement can be safely and effectively performed under local anesthesia in the office cystoscopy room. This procedure could free operating room time, reduce costs and minimize side effects of general anesthesia.

Resonance Metallic Stents Do Not Effectively Relieve Extrinsic Ureteral Compression in Pediatric Patients

Use of metallic stents (Resonance) has been reported in the literature to be effective in relieving extrinsic obstruction in adults. Successful patency rates have been reported to be around 83.3%. The use of Resonance stents in children has not been reported. We present our experience with these stents in addressing extrinsic ureteral obstruction in the pediatric population. We identified two patients who underwent placement of Resonance stents for extrinsic compression at the Children's Hospital of the University of Pittsburgh Medical Center. The first patient is a 12-year-old girl with a solitary left kidney who had a diagnosis of pelvic rhabdomyosarcoma; she was treated with surgery followed by adjuvant chemoradiation. Two years post-treatment, worsening renal function secondary to ureteral strictures developed. The second patient is a 14-year-old girl with a history of Gardner syndrome. Recurrent desmoid tumors developed in her pelvis and retroperitoneum that led to right ureteral obstruction, necessitating a nephrostomy tube. Both patients underwent successful technical placement of a Resonance stent. The time to failure for patient 1 was 3 months and for patient 2, 3 weeks. The first patient presented to the emergency department 3 months poststent in renal failure with a creatinine level of 13.7 mg/dL. This necessitated nephrostomy tube placement and hemodialysis. Ultimately, she needed an ileal ureter to preserve renal function. She is off hemodialysis and has a creatinine level of 2.2 mg/dL.The second patient, recurrent episodes of pyelonephritis, worsening hydronephrosis, and flank pain developed with just the Resonance stent in place. It was elected to remove the Resonance stent and replace the nephrostomy tube. She needed extensive ureterolysis, a right subtotal ureterectomy with a right to left ureteroureterostomy. We did not find the use of these stents to be effective in children. The time to failure was significantly shorter in children than those reported in the literature for adults.

New Metallic Ureteral Stents: Improved Tensile Strength and Resistance to Extrinsic Compression

Extrinsic ureteral compression challenges a ureteral stent's ability to facilitate urinary drainage and to protect the kidney. Our purpose was to evaluate the performance of new metallic coil-based ureteral stents in terms of tensile strength and radial compression force. Three stent designs tested from Prosurg Inc included Passage 7.0F, Snake 6.0F, and Snake 7.0F with the straight section covered with a biocompatible polymer tubing. A MTS Microbionix Testing System using Testworks II software, vibration isolation table, and a 5-N load cell were used to measure tensile and compressive strength. Stents were placed in hydraulic grips and stretched at a rate of 5 mm/s for 1 second under uniaxial tension. Extrinsic compression was exerted in 0.1-mm increments to maximum compression. The Young Modulus, E, was calculated from each trial using engineering stress. Data were analyzed using Mann-Whitney and t tests. The Passage, Snake 6F, and Snake 7F stents had tensile strengths of 27±3, 5±0.1, and 73±26 kPa, respectively. Mann-Whitney tests show statistically significant difference between stents (P<0.05). Elastic modulus needed to cause extrinsic compression was highest for Snake 6F (145,842±14332 Pa) compared with that of Passage (124,999±3182 Pa) and Snake 7F (126,132±19316 Pa), (P<0.05). The Snake 6F stent had the lowest tensile strength and was least resistant to extrinsic compression. The Snake 7F had the highest tensile strength and was most resistant to extrinsic compression. All three stents are more resistant to extrinsic compression than the Applied Silhouette or Cook Resonance, yet have lower tensile strengths.

1937 OFFICE-BASED ENDOUROLOGY USING FLUOROSCOPIC GUIDANCE: CLINICAL OUTCOMES AND COST-EFFECTIVENESS

You have accessJournal of UrologyStone Disease: New Technology/SWL, Ureteroscopic or Percutaneous Stone Removal1 Apr 20111937 OFFICE-BASED ENDOUROLOGY USING FLUOROSCOPIC GUIDANCE: CLINICAL OUTCOMES AND COST-EFFECTIVENESS Boris Gershman, Brian Eisner, and Dianne Sacco Boris GershmanBoris Gershman Boston, MA More articles by this author , Brian EisnerBrian Eisner Boston, MA More articles by this author , and Dianne SaccoDianne Sacco Boston, MA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.2118AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Endourologic procedures are increasingly being performed in the office. We examined the clinical outcomes and cost-effectiveness of endourologic procedures performed in the office using standard fluoroscopy under local anesthesia. METHODS We performed a retrospective review of all patients who underwent ureteral stent placement, ureteral stent exchange, or ureteral catheterization with retrograde pyeolography or BCG instillation in the office under topical anesthesia using fluoroscopic guidance from 9/2008 - 12/2009. Cost data was estimated from Medicare 2010 non-facility physician fees and Ambulatory Payment Classification (APC) reimbursements. RESULTS Procedures were attempted in 65 renal units in 38 patients (13 male, 25 female) with a mean age of 62.2 years (range 29.1–95.4 years). No procedure was terminated due to patient discomfort. Primary ureteral stent placement was successful in 23/24 (95.8%) renal units. Ureteral stent exchange was successful in 19/22 (86.4%) renal units. Ureteral catheterization with retrograde pyelography or BCG instillation was successful in 19/19 renal units. Indications for stent placement or exchange were ureteral stone (14/30, 46.7%), malignant extrinsic ureteral compression (8/30, 26.7%), benign extrinsic ureteral compression (3/30, 10%), ureteral stricture (2/30, 6.7%), ureteropelvic junction obstruction (2/30, 6.7%), and hydronephrosis of unknown etiology (1/30, 3.3%). The total cost of stent placement/stent exchange/retrograde pyelography is $599/$599/$346 when performed in the office compared with $2,306/$2,306/$2,279 when performed in the ambulatory surgical suite. The total cost savings for the 38 patients in this study was approximately $95,601, including excess cost from failure in the office. CONCLUSIONS Ureteral stent placement, exchange, and catheterization can be performed safely and effectively in the office in both men and women. This avoids general anesthesia, provides convenience to patient and clinician, and represents a substantial cost-savings for the healthcare system. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e775 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Boris Gershman Boston, MA More articles by this author Brian Eisner Boston, MA More articles by this author Dianne Sacco Boston, MA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

1938 RISK OF DIABETES MELLITUS AND HYPERTENSION AFTER EXTRACORPOREAL SHOCK WAVE (ESWL) THERAPY FOR URINARY STONE DISEASE

INTRODUCTION AND OBJECTIVES: Endourologic procedures are increasingly being performed in the office. We examined the clinical outcomes and cost-effectiveness of endourologic procedures performed in the office using standard fluoroscopy under local anesthesia. METHODS: We performed a retrospective review of all patients who underwent ureteral stent placement, ureteral stent exchange, or ureteral catheterization with retrograde pyeolography or BCG instillation in the office under topical anesthesia using fluoroscopic guidance from 9/2008 12/2009. Cost data was estimated from Medicare 2010 non-facility physician fees and Ambulatory Payment Classification (APC) reimbursements. RESULTS: Procedures were attempted in 65 renal units in 38 patients (13 male, 25 female) with a mean age of 62.2 years (range 29.1–95.4 years). No procedure was terminated due to patient discomfort. Primary ureteral stent placement was successful in 23/24 (95.8%) renal units. Ureteral stent exchange was successful in 19/22 (86.4%) renal units. Ureteral catheterization with retrograde pyelography or BCG instillation was successful in 19/19 renal units. Indications for stent placement or exchange were ureteral stone (14/30, 46.7%), malignant extrinsic ureteral compression (8/30, 26.7%), benign extrinsic ureteral compression (3/30, 10%), ureteral stricture (2/30, 6.7%), ureteropelvic junction obstruction (2/30, 6.7%), and hydronephrosis of unknown etiology (1/30, 3.3%). The total cost of stent placement/stent exchange/retrograde pyelography is $599/$599/$346 when performed in the office compared with $2,306/$2,306/$2,279 when performed in the ambulatory surgical suite. The total cost savings for the 38 patients in this study was approximately $95,601, including excess cost from failure in the office. CONCLUSIONS: Ureteral stent placement, exchange, and catheterization can be performed safely and effectively in the office in both men and women. This avoids general anesthesia, provides convenience to patient and clinician, and represents a substantial costsavings for the healthcare system.

Wegener's Granulomatosis: A Rare Cause of Hydronephrosis

A seventy-one-year-old woman was hospitalized at our institution for a right-sided “renal colic” associated with an infectious background. Alithiasic ureterohydronephrosis was diagnosed by imaging. A urinary diversion was thus performed using a double J endoureteral stent. The etiologic assessment of the hydronephrosis showed the presence of a periureteral mass that caused extrinsic ureteral compression. After surgical excision of the ureteral lesion, the Wegener's granulomatosis diagnosis was established. This report is the clinical description of a case of “atypical” Wegener's granulomatosis revealed by the onset of a ureteral disease mimicking a neoplastic process.

A Rare Presentation of AKI: Gastric Infiltration of the Bladder Wall

We describe the case of a man who presented with back pain and acute kidney injury and was found to have bilateral ureteral obstruction, which initially corrected with ureteral stents. Imaging studies showed thickening of the bladder. Shortly thereafter, he developed obstructive jaundice, pancreatitis, recurrence of renal failure, and was diagnosed with advanced gastric cancer after a laparotomy revealed peritoneal carcinomatosis. The patient deteriorated rapidly after diagnosis. While peritoneal carcinomatosis, ureteral metastases, and extrinsic ureteral compression have been recognized in gastric cancer, obstructive renal failure due to tumor infiltration of the bladder wall is seldom described. We present this case as an unusual cause of acute renal failure and presentation of gastric cancer.

Metallic Full-Length Ureteral Stents: Does Urinary Tract Infection Cause Obstruction?

Metallic ureteral stents promise to offer superior upper urinary tract drainage with extended exchange intervals and freedom from extrinsic compression in patients with advanced malignancy or other significant obstructing retroperitoneal or pelvic processes. Existing literature indicates a variable experience with these relatively new devices, with some investigators reporting excellent results and long problem-free intervals, and others reporting less enthusiastic outcomes. We report a retrospective review of a series of five sequential patients undergoing placement of Resonance® (Cook Medical, Bloomington, IN) metallic ureteral stents for extrinsic ureteral compression refractory to placement of traditional (polymer) ureteral stents. Of five patients reviewed, three (60%) required additional operative intervention for stent migration or malposition. Four patients (80%) died of their primary malignancy <12 months after metallic stent placement. Four (80%) of five patients had obstruction of their stents demonstrated with nuclear renography and/or other imaging, and three (60%) required removal and alternative means of urinary tract drainage within 4 months of placement due to obstruction, intractable pain, or migration. Four patients (80%) had urinary tract infections (UTIs) within 4 months of stent placement. No obstruction was seen due to extrinsic ureteral compression after stent placement. Metallic ureteral stents may have utility for patients with pathological processes causing extrinsic ureteral compression refractory to the use of traditional polymer ureteral stents. However, metallic ureteral stents are not immune to obstruction, migration, and associated discomfort. Stent obstruction appears to be increased in patients with postoperative UTI.

Ureteral Metal Stents: 10-Year Experience With Malignant Ureteral Obstruction Treatment

Ureteral patency in malignant ureteral obstruction cases is a therapeutic challenge. We report our long-term experience with palliative treatment for extrinsic malignant ureteral obstruction with percutaneous placement of metal mesh stents. From January 1996 to December 2005, 90 patients with a mean age of 59 years (range 35 to 80) with ureteral obstruction due to extrinsic ureteral compression and/or encasement by primary or metastatic tumors, or retroperitoneal lymphadenopathy underwent implantation of self-expandable metal mesh stents. A total of 119 ureters were managed. Followup included urinalysis, blood biochemistry tests and transabdominal ultrasound or intravenous urography. The technical success rate of percutaneous antegrade insertion of ureteral self-expandable metal mesh stents was 100%. Renal biochemistry normalized and hydronephrosis gradually resolved 1 to 2 weeks after stent insertion. Median followup was 15 months (range 8 to 38). Hyperplastic reaction and/or encrustation, or tumor ingrowth developed in 45 stents. Secondary intervention, such as repeat balloon dilation and coaxial stenting, was done to improve patency. Migration was observed in 13 metal stents. The primary and secondary patency rates during followup were 51.2% and 62.1%, respectively. A double pigtail or external-internal stent was inserted in 45 cases in which secondary interventions did not ensure patency. Internal drainage of extrinsic malignant ureteral obstruction with metal mesh stents provides long-term decompression of the upper urinary tract in select cases. Certain problems limit the application of metal mesh stents in the ureter. Further studies are warranted to identify independent predictors of ureteral patency after the application of metal stents for malignant obstruction.

Analysis of Ureteral Stent Compression Force and its Role in Malignant Obstruction

Extrinsic ureteral obstruction can be a challenging entity for the urologist since half of the ureteral stents placed for malignant obstruction fail. We evaluated the resistance to radial compression of various stents. Silhouette(R) 4.6Fr, 6Fr and 8Fr, Sof-Curl Tecoflex 6Fr, Resonance 6Fr, Polaris Ultra 6Fr and 7Fr, and Percuflex 6Fr and 8Fr stents were tested. The force needed to compress the stent to 50% of its original external diameter was measured at 3 locations along the stent length, including proximal, middle and distal. Statistical analysis was performed. Statistically greater force was required to compress the Resonance and Silhouette stents compared to all others tested. These results were maintained at all 3 locations along the stent. Only the Polaris 6Fr stent differed in resistance to compression along the stent length. The significantly higher forces required to compress the Resonance and Silhouette stents may translate into improved success in patients with malignant ureteral obstruction.

Retrograde Ureteral Stents for Extrinsic Ureteral Obstruction: Nine Years’ Experience at University of Michigan

To review our experience with retrograde ureteral stenting for extrinsic ureteral obstruction because previous reports have suggested only moderate success. We performed a retrospective review of the course of patients who underwent retrograde ureteral stent placement from March 1996 to April 2005. The gathered clinical parameters included stent failure, which was defined as any ureteral unit (UU) that remained obstructed. A total of 54 patients treated for extrinsic ureteral compression, representing 87 UUs, were followed for an average of 16 months (range 0.7 to 98) in successful cases. Of the stents, 68% were placed for malignancy, 23% for retroperitoneal fibrosis, and 9% for benign masses. The overall success rate was 84%, with malignancy, retroperitoneal fibrosis, and benign masses having an 81%, an 85%, and a 100% success rate, respectively. Fourteen UUs failed, with a mean time to stent failure of 4.8 months (range 0.07 to 27). Multiple stents were placed in 54 UUs, with a mean of 5.5 stent exchanges, at a mean interval of 3.6 months. On univariate analysis, only greater posttreatment creatinine was associated with stent failure (P <0.01), although stents placed for localized disease tended to be more successful than those placed for regional disease (100% versus 81%, P = 0.07). If initial stent placement was possible, extrinsic ureteral obstruction was managed successfully with retrograde ureteral stent placement in 84% of cases. Because no preoperative characteristics could be identified, except for a trend toward less success in cases of regional disease, retrograde stenting can be considered first-line treatment in patients with extrinsic ureteral obstruction.

In-Vivo Evaluation of Flow Characteristics of Novel Metal Ureteral Stent

To characterize the flow of a novel ureteral stent composed of a nickel-cobalt-chromium-molybde-num alloy and compare it with flow in a standard ureteral stent. Six 6F Resonance stents and six 6F standard Black Beauty ureteral stents were placed in six Yucatan minipigs, with each pig serving as its own control. Flow assessment was performed on all stents via a nephrostomy tube delivering a standard rate of 0.9% saline at 35 cm H(2)O. Flow studies on the standard stents encompassed extraluminal (i.e., lumen of stent occluded with a guidewire), intraluminal (i.e., ureter secured to stent with a constricting suture), and combined (i.e., open lumen without constricting suture) flow. In the Resonance stent, only combined and intraluminal flow could be addressed, as there is no access to the lumen of this stent. With the Resonance stent, intraluminal flow was much greater than combined flow, with mean values of 5.15 mL/min and 2.50 mL/min, respectively (P = 0.057; SD = 7.73). Intraluminal flow was similar to combined flow in the 6F standard stent, with mean values of 7.34 mL/min and 7.30 mL/min, respectively (P = 0.88; SD = 1.76). The standard stent had significantly greater combined flow than the Resonance stent (P = 0.023) but not intraluminal flow (P = 0.247). Of note, whereas it was possible to occlude the 6F standard stent completely with a ureteral ligature (i.e., no guidewire placed in the lumen), it was not possible to occlude the Resonance stent regardless of how tightly the suture was tied. The Resonance metal alloy stent provides less overall flow than a standard stent. However, under circumstances of extrinsic ureteral compression sufficient to occlude a standard stent (e.g., extrinsic compression plus an internal guidewire), the metal stent continues to provide satisfactory drainage.

The Management of Malignant Ureteral Obstruction Treated with Ureteral Stents

We developed an algorithm for the management of ureteral obstruction due to malignant extrinsic compression. We retrospectively reviewed all ureteral stents placed for noncalculous reasons at our institution from January 1, 1990 to January 1, 2004. Further clinical information was gathered from 157 patients with malignant extrinsic ureteral compression. Failure was defined as recurrent ureteral obstruction or an inability to place stents cystoscopically. A total of 157 patients underwent retrograde ureteral stent attempt for malignant extrinsic ureteral obstruction. Mean patient age was 54.7 years (range 23 to 83) and average followup was 13.6 months. Of our patients 61% were women, and the most common cancer diagnoses were ovarian cancer (in 26), lymphoma (17) and cervical cancer (16). A total of 24 patients required immediate percutaneous nephrostomy (PCN) referral. There were 32 patients who experienced a late failure and required PCN (average 180 days after initial stent), and 83 patients in our series (52.9%) who experienced 110 major complications. Type of cancer did not predict need for PCN. However, when invasion into the bladder was noted on cystoscopy, 55.9% (19 of 34, p = 0.008) progressed to PCN referral. A total of 77 patients underwent stent replacement on average 2.8 times and with an interval of 95 days. In our series patients with malignant extrinsic ureteral compression presenting for ureteral stent(s) experienced a failure rate of 35.7% (56 of 157). Invasion at cystoscopy had a significant predictive value for progression to PCN. We present an algorithm on the management of extrinsic malignant ureteral obstruction.

Improved tumor stent for internal palliative urinary diversion

The disadvantages of high flexible endoureteral stents (DJ) in case of tumorinduced extrinsic ureteral compression are due to an insufficient vertical stability of the used stents leading to stent-compression and consecutive hydro- or pyonephrosis. The new developed tumor-stent used in case of tumor-induced ureteral compression is available from 6 to 8 French in diameter and 24 to 32 cm in length. The corpus consists of a combination of high-stability plastics but is of sufficient elasticity in length. Both ends consist of extremely elastic J-parts guaranteeing an exact fixation. As against common DJ's with the same outside-diameter the new stent has a comparable interior diameter and compared to used "old" tumor stents promises a higher interior flow in case of extrinsic diseases. The application can be undertaken in well-known technique, needs no special instrumentation and no learning-curve. To date 52 stents at our urologic departments were placed without any problems, the latest remaining for 15 months. Tumor-induced compression or a higher rate of encrustation could not be seen. All patients tolerated these stents well. In our opinion the new stabilized endoureteral stent can be seen as a better solution instead of percutaneous nephrostomy or frequent stent changing in patients with tumor induced extrinsic ureteral compression.

New endoureteral double-J stent resists extrinsic ureteral compression.

The disadvantages of highly flexible endoureteral (double J) stents in the face of tumor-induced extrinsic ureteral compression are a consequence of insufficient cross-sectional stability, leading to stent compression and thus to hydronephrosis or pyonephrosis. The newly developed tumor stent, which is used in cases of tumor-induced ureteral compression, is available in sizes from 6F to 8F in diameter and 24 to 32 cm in length. The shaft consists of a combination of high-stability plastics that presents sufficient elasticity in length. Both ends are made of extremely elastic J parts, guaranteeing stable fixation. Compared with common double-J stents with the same outside diameter, the tumor stent possesses a comparable interior diameter and compared with available stents promises sufficient interior flow in the face of extrinsic diseases. The application can be undertaken using well-known endoscopic techniques, needs no special instrumentation, and entails no learning curve. To date, 49 stents were placed at our urologic departments without any problems, the latest stent remaining for 15 months. Tumor-induced compression or a higher rate of encrustation were not seen. All patients tolerated these stents well. In our opinion, the new stabilized endoureteral stent can be seen as a better solution than percutaneous nephrostomy or frequent stent changing to tumor-induced extrinsic ureteral compression.

THE USE OF 2 IPSILATERAL URETERAL STENTS FOR RELIEF OF URETERAL OBSTRUCTION FROM EXTRINSIC COMPRESSION

Purpose We present our early experience with the novel approach of placing 2 parallel stents simultaneously in extrinsically obstructed ureters in which single stents had failed. The increased stiffness of 2 stents reduces kinking and luminal compression, and the potential space between the stents likely preserves flow around as well as through them. Materials and Methods Four patients recently presented with ureteral obstruction secondary to nonurinary tract malignancies. Previous stenting with a single 6F Double-J * * Medical Engineering Corp., New York, New York. stent had failed in all cases. Three patients experienced flank pain and 1 had persistent azotemia within 3 days of initial stent placement. All patients had significant residual sonographic hydronephrosis despite good stent position. In all cases cystoscopy/stent exchange was performed under local anesthesia with intravenous sedation. Parallel 4.7F Double-J stents were placed simultaneously over 2, 0.035 hydrophilic coated glide wires under fluoroscopic guidance after removal of the malfunctioning 6F stent. Results Stent placement was uneventful in all 4 patients with prompt drainage of contrast material seen after parallel ipsilateral stent placement. Patients tolerated the double 4.7F parallel stents with no discernible difference in irritative symptoms compared to single 6F stents. Flank pain and azotemia resolved in 3 patients, and hydronephrosis improved in all 4 after placement of parallel Double-J stents. All patients remain alive with a mean followup of 5.8 months (range 4 to 8). Except for 1 patient who later underwent ureterolysis, each had subsequently had the stent changed every 3 months. No patient has required proximal urinary diversion (that is percutaneous nephrostomy tube). Conclusions Placement of 2 ipsilateral parallel ureteral stents simultaneously is an easy technique. It may obviate percutaneous nephrostomy tube placement in patients in whom drainage with a single stent failed, especially in cases of extrinsic ureteral compression.