Ureteral Occlusion Research Articles

Refined pluck technique by ureteral occlusion and transurethral cystorrhaphy in nephroureterectomy with bladder cuff excision for upper tract urothelial carcinoma

Refined pluck technique by ureteral occlusion and transurethral cystorrhaphy in nephroureterectomy with bladder cuff excision for upper tract urothelial carcinoma

Rare giant bladder stone with the size of an adults' fist in healthy young male

Rare giant bladder stone with the size of an adults' fist in healthy young male

Safety and efficacy of using the stone cone and an entrapment and extraction device in ureteroscopic lithotripsy for ureteric stones

ObjectiveTo assess the safety and efficacy of using a stone cone and an entrapment and extraction device (N-Trap®, Cook Urological, Bloomington, IN, USA) to avoid stone retropulsion during ureteroscopic lithotripsy for ureteric stones. Patients and methodsThis retrospective comparative study included 436 patients treated with ureteroscopic lithotripsy for a single ureteric stone from February 2011 to January 2014. The diagnosis of a stone was confirmed by plain spiral computed tomography in all cases. Patients were divided according to the ureteric occlusion device applied to avoid stone retropulsion during pneumatic lithotripsy into three groups; group 1 (156) had no instruments used, group 2 (140) in whom the stone cone was applied, and group 3 (140) in whom the N-Trap was used. Patient demographics, stone criteria, operative duration and complications, and success rates (complete stone disintegration with no upward migration) were reported and analysed statistically. ResultsThe stone was in the lower ureter in >55% of patients in all groups. The mean (SD) of maximum stone length was 9.8 (2.5), 10.4 (2.8) and 9.7 (2.9) in groups 1–3, respectively. The use of the stone cone or N-Trap did not significantly increase the operative duration (P=0.13) or complication rates (P=0.67). There was a statistically significant difference (P<0.001) favouring groups 2 and 3 for retropulsion and success rates, being 83.3% in group 1, 97.1% in group 2 and 95.7% in group 3. ConclusionThe stone cone and N-Trap gave high success rates in preventing stone retropulsion during ureteric pneumatic lithotripsy. Both devices caused no increase in operative duration or complications when used cautiously.

Postoperative ureteral leak treated using a silicone-covered nitinol stent.

Ureteral fistula is a serious complication of abdomino-pelvic surgeries, often resulting in poor outcomes owing to lack of proper treatment. We report the case of a 49-year-old woman who underwent placement of a silicone-covered ureteral occlusion stent in her right ureter for the management of ureteral leakage after pelvic surgery. A ureterogram obtained 18 months following the stent placement confirmed that there was no stent migration or additional urine leakage. We propose that the silicone-covered ureteral occlusion stent is practical, fast, and safe for the management of ureteral leakage.

Risk Factors for Ureteral Occlusion during Transvaginal Uterosacral Ligament Suspension: A Retrospective Case-Control Study

Risk Factors for Ureteral Occlusion during Transvaginal Uterosacral Ligament Suspension: A Retrospective Case-Control Study

In Vitro Evaluation of the Occlusive Properties of Latex-Covered Amplatzer Vascular Plugs for Transrenal Ureteral Occlusion

To evaluate the occlusive properties of latex-covered Amplatzer Vascular Plugs (AVPs) for transrenal ureteral occlusion in vitro. Latex-covered AVPs type I and II (diameter 8, 10, 12, 14, and 16 mm) were used as occlusive devices. Radial force of an AVP was measured using simulated ureteral diameters of 4 to 12 mm. Occlusive properties were examined in a silicone tube (inner diameter 6 mm) with measurement of drainage time of a 40 cm water column. In complete occlusion, the maximum pressure that the plug was able to withstand was determined at different temperature levels. Statistical analysis of drainage time was performed in a general linear model (GLM) and using correlation analyses. Explanted porcine ureters were used to simulate physiologic conditions. Pressure measurements were performed until leakage, plug dislocation, or rupture of the ureter occurred. Radial force depended on AVP type, size, ureteral diameter, and temperature. The 16-mm AVP II showed the highest radial force of more than 5 N (ureteral diameter 4 mm, body temperature). All AVP I showed water leakage and plug dislocation. Drainage time of the AVP II depended significantly on plug size and temperature and correlated with radial force (r=0.731, P<0.001). In complete occlusion, water leakage occurred at 500 to 1000 cm H2O and dislocation between 500 to more than 2000 cm H2O. In porcine ureters, leakage occurred at room temperature between 19 to 93 cm H2O. At body temperature, all AVP II occluded the ureter completely. Latex-covered AVP II (diameter 8-16 mm) can effectively occlude the ureter, especially considering remodeling of the nitinol at body temperature. Large plug diameters can exert enough radial force even in dilated ureters to allow for successful occlusion. Because deployment of a 16-mm latex-covered AVP II can be technically difficult, we advocate the use of 12- or 14-mm AVP II for transrenal ureteral occlusion. AVP Is are not suitable for ureteral occlusion.

Abstract No. 386 - Permanent ureteric occlusion for urinary diversion: TIPS and tricks

Abstract No. 386 - Permanent ureteric occlusion for urinary diversion: TIPS and tricks

Ureteroarterial fistula from ureteral stump: a challenging case.

Ureteroarterial fistula (UAF) is a relatively rare condition with about 150 cases reported in the literature. Since it is a potentially life-threatening condition, a prompt diagnosis and treatment are crucial. We present here a rare, challenging case of UAF diagnosed after left nephrectomy, thus involving the ureteral stump. The difficult diagnosis and treatment by contemporary use of endovascular stent placement and ureteral occlusion by mean of metallic coils and Onyx injection are discussed.

Effect of hydrogen sulfide on expressions of ectodermal dysplasia-1 and kidney injury molecule-1 of renal interstitial in rats with unilateral ureteral occlusion

Objective To investigate the effects of hydrogen sulfide(H2S) on the tubular interstitial fibrosis and on the levels of kidney injury molecule-1(KIM-1) and ectodermal dysplasia-1(ED-1) in the process of renal interstitial fibrosis in rats with unilateral ureteral occlusion(UUO). Methods Ninety-six Sprague-Dauley(SD) male rats were divided into 4 groups randomly: sham-operated group(n=24), model group(n=24), low-dose therapy group(n=24) and high-dose therapy group(n=24). The rats in the model group and treatment groups were ligated at the left ureter and UUO was induced, meanwhile, the rats in the control group were free from the left ureter ligation. Rats received sodium hydrosulfide(NaHS) in traperitoneatly(1.4 μmol/kg, twice a day), and NaHS(7.0 μmol/kg, twice a day), respectively. Rats in sham-operated group and the model group were injected intraperitoneally with identical voluminal 9 g/L saline. Eight rats in each group were sacrificed randomly at the 7 days, 14 days and 21 days, respectively. The concentration of plasma H2S was detected. Renal tubular interstitial damage and interstitial fibrosis were evaluated with routine HE staining and Masson staining under microscope, and both of them were used to evaluate the obstruction of renal histopathological changes. The expressions of ED-1 and KIM-1 were measured with immunohistochemical staining. Results 1. The pathological findings showed that the renal tubular interstitial changes were not obvious in the sham-operated group. The tubular epithelial cells in the model group and treatment groups showed swelling and vacuoles degeneration, with renal interstitial broadening, interstitial cells and extracellular matrix increasing. The renal tubular interstitial pathological injury of model group and treatment group were more serious than those in the sham-operated group at each time point(P 0.05).2. Immunohistochemical analysis showed that expressions of ED-1 and KIM-1 in renal tubular interstitices in the model group and the treatment groups were higher than those in the sham-operated group at each time point(P 0.05).3. Plasma H2S levels in model group and treatment group were lower than those in the sham-operated group at each time point(P 0.05). Conclusions H2S implements renal protection effect partly by reducing the expression of ED-1 and KIM-1 in tubule interstitices to ease tubular interstitial fibrosis. Key words: Hydrogen sulfide; Tubular interstitial fibrosis; Uniliteral ureteral obstruction; Ectodermal dyspla-sia-1; Kidney injury molecule-1

Multicenter Experience of the Newly Designed Covered Metallic Ureteral Stent for Malignant Ureteral Occlusion: Comparison With Double J Stent Insertion

This study was designed to evaluate the effectiveness of the newly designed covered metallic stent (CMS) for malignant ureteral obstruction by comparing with double J stent (DJS). CMSs were placed for malignant ureteral obstruction caused by various types of cancers for 42 ureters in 32 patients from 7 institutes. Retrospective data were collected for DJSs, which included 72 malignant ureteral occlusions in 56 patients from a single institute. Twenty-seven DJSs were placed percutaneously, and 45 DJSs were cystoscopically inserted. Technical failure of the CMS group was compared with that of the radiologically inserted DJS group. Primary patency of the CMS group was compared with assisted primary patency of the DJS group. Technical failure of the CMS group is lower than that of the radiologically inserted DJS group: 0% (0/42) vs. 25.9% (7/27; p = 0.002), respectively. Primary patency of the CMS group is better than assisted primary patency of the DJS group (p = 0.012). Primary patency of the CMSs is 100, 94.5, 74.7, 70.3, 65.3, 65.3, and 65.3% at 1, 3, 6, 9, 12, 18, and 24 months, respectively. Assisted primary patency of the DJS is 78.6, 75.1, 59.1, 48.7, 38.7, and 37.8% at 1, 3, 6, 9, 12, and 18 months, respectively. No serious complications were noted in the CMS group. Migration of the metallic stent occurred in one patient (2.3%). Covered metallic stent placement for malignant ureteral obstruction is superior to the double J stent placement in terms of technical success and patency.

Transrenal Ureteral Occlusion Using the Amplatzer Vascular Plug II: A New Interventional Treatment Option for Lower Urinary Tract Fistulas

This study was designed to evaluate the results of a novel technique for transrenal ureteral occlusion using an Amplatzer vascular plug (AVP) II in patients with urinary fistulas. We retrospectively evaluated the results of transrenal occlusion of 15 ureters in 9 hospitalized patients [8 females, 1 male, mean age 64 (range 52-79) years] suffering from pelvic malignancy (4 cervix-carcinomas, 3 bladder-carcinomas, 1 colorectal carcinoma, and 1 vulva-carcinoma). Seven patients were treated for urinary fistulas (4 ureteroenteral, 3 vesicovaginal); the others showed ileum-conduit-insufficiency and Mainz-pouch incontinence, respectively. From 2008 to 2009, an AVP was used in combination with coils and tissue adhesive (n = 5). Since 2009, ureteral occlusions were performed using a latex-covered AVP (n = 10). All patients had previous nephrostomy with only incomplete clinical improvement. Fourteen of 15 interventions were technically successful. Four of five ureters occluded with a combination of AVP, coils, and tissue adhesive were permanently sealed after a single procedure, whereas one showed slight leakage. After placement of two additional coils 20 days later, permanent occlusion was achieved [mean follow-up 195 (range 30-687) days]. Nine of ten ureters occluded with a latex-covered AVP were completely sealed after a single intervention [mean follow-up 152 (range 10-462) days]. In one case, the latex-cover dislocated during implantation. The AVP alone failed to provide complete dryness. There were no dislocations of the AVP or other major complications. Transrenal ureteral occlusion using an AVP is a practical, simple, and quick method and can be advantageous in palliative patients suffering from pelvic malignancy.

Endoscopic-guided sclerotherapy for renal-sparing treatment of idiopathic renal hematuria in dogs: 6 cases (2010–2012)

To describe the use of sclerotherapy for the renal-sparing treatment of idiopathic renal hematuria (IRH) in dogs and report clinical outcomes. Retrospective case series. 6 dogs (8 renal pelvises) with IRH. Medical records of dogs that underwent sclerotherapy were reviewed. Each ureterovesicular junction was identified cystoscopically to determine the side of bleeding, and a retrograde ureteropyelogram was performed with endoscopic and fluoroscopic guidance. A ureteropelvic junction balloon was used for ureteral occlusion, and pelvis filling volumes were recorded. A povidone iodine mixture, followed by a sterile silver nitrate solution, was infused into the renal pelvis. A double-pigtail ureteral stent was placed after the procedure. Information on preprocedure and postprocedure biochemical changes, imaging parameters, and clinical outcomes was obtained. 6 dogs (5 males and 1 female) had sclerotherapy for unilateral (4) or bilateral (2) bleeding. Five were right-sided and 3 were left-sided. The median age and weight of dogs were 3 years and 42.4 kg (93.28 lb), respectively. Median procedure time was 150 minutes. One dog that did not have a ureteral stent placed following the procedure developed short-term signs of renal pain and pyelectasis. Cessation of macroscopic hematuria occurred in 4 of 6 dogs (median, 6 hours). Two additional dogs improved moderately. Median follow-up time was 8 months (range, 3.5 to 20.5 months). Topical sclerotherapy for IRH was safe and effective. Local sclerotherapy for IRH in dogs could be considered a valuable and minimally invasive renal-sparing treatment over ureteronephrectomy.

Educational Exhibit Abstract No. 243 - IR management of ureteral leaks

Learning Objectives To educate and inform the reader about the management of ureteral leaks utilizing temporary and permanent treatment options. Background Ureteral leaks can develop in the setting of iatrogenic, inflammatory, neoplastic, and post-traumatic conditions. Urinary diversion is a well-established technique that gives the body time to heal and seal the leak in the ureter. Traditional methods range from percutaneous nephrostomy tubes to double-J ureteral stents. However, there are instances in which temporary or permanent occlusion is required for complete urinary diversion when traditional methods are unsuccessful. These treatment options are less invasive options than those offered by surgeons or urologists. A thorough understanding of the treatment options will help the interventional radiologist provide the best and least invasive care for the patient with a ureteral leak. Clinical Findings/Procedure Details Multiple cases demonstrating ureteral leaks that were managed with a variety of methods ranging from percutaneous nephrostomy to permanent ureteral occlusion to allow for urinary diversion. Imaging findings and key procedural tips are discussed where applicable. Indications for further imaging or additional work-up are addressed. Conclusion and/or Teaching Points Urinary diversion is an effective method of treating ureteral leaks to allow for either healing of the injured segment or for complete urinary diversion when distal drainage is not desired. Various methods are described and can be utilized in the hands of a skilled interventional radiologist.

Cost-Effectiveness of Anti-Retropulsion Devices for Ureteroscopic Lithotripsy

We evaluated the cost-effectiveness of anti-retropulsion devices used during ureteroscopic lithotripsy. A decision analysis model was constructed to compare the cost-effectiveness of ureteroscopic lithotripsy with vs without an anti-retropulsion device. The risk of stone retropulsion was determined from published data in the English language literature. Expected value calculations were used to determine whether the additional cost of a device would be cost-effective to prevent secondary procedures used to treat retropulsed stones. Device cost was determined using the average cost of all commercially available devices. It became cost-effective to use an anti-retropulsion device at or above a 6.3% retropulsion rate. The weighted probability of retropulsion with vs without an anti-retropulsion device was 98.1% vs 83.7%. The estimated costs of secondary procedures needed to treat retropulsed stones were $5,290 for shock wave lithotripsy and $6,390 for ureteroscopy. Average device cost was $278. Thus, the average additional cost of ureteroscopic lithotripsy with vs without an anti-migration device would be $384 vs $952. It is cost-effective to use an anti-retropulsion device at a retropulsion rate of greater than 6.3%.

Evaluation of Differential Renal Function and Renographic Patterns in Patients with Dietl Crisis

We analyzed preoperative and postoperative differential renal function and characterized the renographic findings in patients with ureteropelvic junction obstruction associated with Dietl crisis. Patients with Dietl crisis who underwent pyeloplasty between January 2004 and December 2010 were classified by renographic presentation. Patients in group 1 were diagnosed with cortical retention, those in group 2 had an initial obstructed scan (T1/2 of 20 minutes or more and no cortical retention) and those in group 3 had an initial nondiagnostic scan (T1/2 of less than 20 minutes and no cortical retention). Renographic parameters were used to analyze each group. A total of 59 patients met criteria for study inclusion. The 13 patients in group 1 demonstrated the most significant recovery of function after pyeloplasty (mean differential renal function change 13.59%). The 38 patients in group 2 exhibited a mean differential renal function change of 43.06% (range 20% to 54.6%) and mean preoperative T1/2 of 64.31 minutes. Pyeloplasty was performed in all 8 patients in group 3 based on subsequent diagnostic scan (4 patients) or increased hydronephrosis on other imaging associated with further symptomatic episodes (4). Initial renographic patterns noted in group 3 included biphasic curves, diminished clearance after 15 minutes upright or symptoms despite nonobstructive drainage. Interpretation of diuretic renography requires the assimilation of multiple parameters since patients with Dietl crisis can exhibit variability in renographic patterns due to the intermittent nature of ureteropelvic junction obstruction. Cortical retention represents a specific and pathognomic finding of acute ureteropelvic junction obstruction. With appropriate evaluation of these parameters, obstruction can be reliably diagnosed and appropriate surgical candidates chosen.

The effects of Kangxianling on renal fibrosis as assessed with a customized gene chip

ObjectiveTo determine the mechanisms by which Kangxianling (KXL) treats renal interstitial fibrosis using a customized gene chip. MethodsTwelve out of 18 specific pathogen-free sprague dawley (SPF SD) rats underwent a unilateral ureteral occlusion. These rats were then randomly assigned into either the model unilateral ureteral obstruction (UUO) or Kangxianling (KXL) group. The other six rats were assigned to the sham-operated group. The UUO and sham-operated groups were given normal saline via intragastric administration, whereas the KXL group was given KXL via intragastric administration. All rats were sacrificed for renal tissue collection (i.e. left nephridial tissue), and the detection of genetic changes with the customized chip. ResultsCompared to the sham-operated group, transforming growth factor-β1 (TGF-β1), Smad2, and Smad3 genes were significantly up-regulated in the UUO group, with >1.5-fold rise (P<0.01). The Smad7 gene was significantly reduced in the UUO versus sham-operated group, with a down-regulation of > 1.5-fold (P<0.01). In the KXL group, TGF-β1 Smad2, and Smad3 genes were significantly reduced compared to the UUO group, with a down-regulation of > 1.5-fold (P<0.01), whereas the Smad7 gene was significantly increased compared to the UUO group, with an up-regulation of > 1.5-fold (P<0.01). ConclusionIt was found that KXL can significantly reduce the gene levels of TGF-β1 Smad2, and Smad3. Immunohistochemistry findings also revealed significantly lower TGF-β1/Smads-mediated gene transcription activity. These findings suggest that KXL may negatively regulate the TGF-β1/Smads signal pathway to inhibit the occurrence of renal fibrosis.

Safety and Efficacy of a Novel Ureteral Occlusion Device

To evaluate the safety of a novel ureteral occlusion device and compare its performance with that of other devices and guidewires. The XenX (Xenolith Medical) was tested in an ex vivo porcine model to determine the percentage of denuded urothelium because of manipulation within the ureter, the capacity to prevent stone migration during laser lithotripsy, stent compatibility, and the ability to be used for stent placement. Comparative evaluations of the insertion forces and maneuverability were conducted in an in vitro ureter model with the XenX, Stone Cone (Boston Scientific), NTrap (Cook Urological), HiWire (Cook Urological), Roadrunner (Cook Urological), and Sensor (Boston Scientific). Stone migration efficacy was measured using a controlled distribution of stones in 4- and 10-mm silicone tubing with the XenX, NTrap, and Stone Cone. The XenX was safely manipulated within the ureter, prevented significant particle migration during laser lithotripsy, and effectively placed stents. The NTrap required the greatest force when attempting to navigate past a stone (P = .0003), followed by the Stone Cone (P = .009), with little difference among the other devices (P > .72). No differences were found for the passing forces (P = .061), interval to pass (P = .30), or number of attempts to pass the stone (P = .68). The XenX prevented stone migration the most, with more notable differences in the 10- than in the 4-mm tubing. Ex vivo evaluations hold promise for the XenX to be safely and effectively used during ureteroscopic procedures. Clinical evaluations are warranted to confirm the safety and performance of the XenX relative to the other ureteral occlusion devices.

1826 STUDY OF SILENT OBSTRUCTION AFTER URETEROSCOPIC MANAGEMENT OF IMPACTED URETERAL STONES

You have accessJournal of UrologyStone Disease: New Technology/SWL, Ureteroscopic or Percutaneous Stone Removal III1 Apr 20121826 STUDY OF SILENT OBSTRUCTION AFTER URETEROSCOPIC MANAGEMENT OF IMPACTED URETERAL STONES Soichi Mugiya, Masao Nagata, Hiroshi Furuse, and Seiichiro Ozono Soichi MugiyaSoichi Mugiya Hamamatsu, Japan More articles by this author , Masao NagataMasao Nagata Hamamatsu, Japan More articles by this author , Hiroshi FuruseHiroshi Furuse Hamamatsu, Japan More articles by this author , and Seiichiro OzonoSeiichiro Ozono Hamamatsu, Japan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.1914AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Improved endoscope and advanced devices have significantly decreased the incidence of complications during ureteroscopy (URS). Despite recent reports suggesting that routine postoperative imaging may not be necessary in all individuals after URS silent obstruction may develop in some, ultimately resulting in renal damage. We evaluated the incidence and factors associated with postoperative abnormal imaging without symptoms after URS for impacted ureteral stones. METHODS We retrospectively reviewed the records of 377 patients who underwent URS for impacted ureteral stones at our institution. Our URS procedure using a small-caliber ureteroscope and a holmium: YAG laser has been reported previously (J. Urol. 171: 89, 2004). All of the patients routinely underwent IVP in order to assess for obstruction or delayed excretion at 1 month after URS. Abnormal imaging was defined when postoperative imaging did not show improvement of hydronephrosis. Patient characteristics as well as endoscopic findings were reviewed to identify factors associated with abnormal post-URS imaging. RESULTS Of the 377 patients 19 (5%) revealed abnormal postoperative imaging without symptoms. All 19 patients underwent secondary ureteroscopy in order to assess and alleviate obstruction. 19 patients with a mean age of 59 years were included. Mean diameter of the initial target stone was 14 mm (range 2-23) with stone location being 13 proximal, 5 distal, and one mid ureter. Mean duration of impaction was 31 months (range 2-84). Second URS revealed obstruction due to ureteral stricture in 16, complete ureteral occlusion in 2 and ureteral tortuosity in 1. Second URS detected a severe ureteral stricture related to laser therapy distal to the successfully treated stone. The obstruction eventually resolved with endoscopic balloon dilation in 17 out of 19 patients. 2 patients ultimately received ureteroureterostomy and 2 were lost to follow-up. Among these 19 patients, initial URS revealed inflammatory ureteral polyps associated with the calculi in 9 and ureteral stricture in 6. Stone location, stone size, operative time, duration of impaction and stone composition were not associated with abnormal post-URS imaging. CONCLUSIONS Our analysis suggests that silent obstruction remains a potentially significant complication after URS for long-term impacted ureteral stones which are frequently associated with ureteral polyps and strictures. Therefore, we recommend that routine postoperative imaging should be performed after URS to avoid the potential complications of unrecognized ureteral obstruction. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e737-e738 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Soichi Mugiya Hamamatsu, Japan More articles by this author Masao Nagata Hamamatsu, Japan More articles by this author Hiroshi Furuse Hamamatsu, Japan More articles by this author Seiichiro Ozono Hamamatsu, Japan More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...

Ureteral Interventions

The pelvic course of the ureter with its close proximity to the iliac artery, pelvic viscera, and other structures predispose to fistula formation. Surgical management of lower urinary tract fistulas is difficult and often ineffective. Nonvascular lower urinary tract fistulas can be managed by urinary diversion with percutaneous nephrostomy to allow for fistula healing. If this fails, ureteral embolization can be very effective; however, this should be preceded by careful evaluation and discussion with the patient as this intervention results in irreversible ureteral occlusion necessitating a diverting nephrostomy catheter indefinitely. A ureteroarterial fistula is a distinct entity compared with nonvascular fistulas with a different approach to management; it can be managed by exclusion of the fistula by endovascular placement of a stent graft across the arterial component of the fistula.

1690 ROUTINE POSTOPERATIVE IMAGING IS IMPORTANT AFTER URETEROSCOPIC MANAGEMENT OF IMPACTED URETERAL STONES

INTRODUCTION AND OBJECTIVES: Improved endoscope and advanced intracorporeal lithotripsy devices have significantly decreased the incidence of complications during ureteroscopy (URS). Despite recent reports suggesting that routine postoperative imaging may not be necessary in all individuals after URS silent obstruction may develop in some, ultimately resulting in renal damage (Weizer AZ, et al. J Urol 168: 46–50, 2002.) We evaluated the incidence and factors associated with postoperative abnormal imaging and assessed the need for routine postoperative imaging after URS. METHODS: We retrospectively reviewed the records of 323 patients who underwent URS for impacted ureteral stones at our institution. Our URS procedure using a small-caliber ureteroscope and a holmium: YAG laser has been reported previously (J. Urol. 171: 89–91, 2004). All of the patients routinely underwent IVP in order to assess for obstruction or delayed excretion at 1 month after URS. Abnormal imaging was defined when postoperative imaging did not show improvement of hydronephrosis. RESULTS: Of the 323 patients 16 (5%) revealed abnormal postoperative imaging without symptoms. All 16 patients underwent secondary ureteroscopy in order to assess and alleviate obstruction. 16 patients with a mean age of 56 years were included. Mean diameter of the initial target stone was 15 mm (range 2–23) with stone location being 11 upper ureter and 5 lower ureter. Mean duration of impaction was 30 months (range 2–72). Second URS revealed obstruction due to ureteral stricture in 13, complete ureteral occlusion in 2 and ureteral tortuosity in 1. Second URS detected a severe ureteral stricture related to laser therapy distal to the successfully treated stone. The obstruction eventually resolved with endoscopic balloon dilation in 14 out of 16 patients. 2 patients ultimately received ureteroureterostomy and 2 were lost to follow-up. Among these 16 patients, initial URS revealed inflammatory ureteral polyps associated with the calculi in 8 and ureteral stricture in 4. Stone location, stone size, operative time, duration of impaction and stone composition were not associated with abnormal post-URS imaging. CONCLUSIONS: Our analysis suggests that silent obstruction remains a potentially significant complication after URS for long-term impacted ureteral stones which are frequently associated with ureteral polyps and strictures. Therefore, we recommend that routine postoperative imaging should be performed after URS to avoid the potential complications of unrecognized ureteral obstruction.