Stent Encrustation Research Articles

Double Loop Ureteral Stent Encrustation According to Indwelling Time: Results of a European Multicentric Study.

Introduction: Double-J ureteral stents are subject to encrustation. Studies have shown that the encrustation onset is linked with indwelling time. In prevention, it is admitted that the Double-J stent indwelt for medium or long term should be replaced periodically. However, in the absence of guidelines, indwelling durations vary with centers' habits, stent indication, and stent materials. Our target was to evaluate the actual ureteral stent medium-/long-term indwelling times and related encrustation rates perceived by urologists in daily practice. Methods: An observational retrospective study was performed over six European centers. All data of all consecutive removed stents of the same material implanted for more than 2 months within a same 2-year referred period were collected. Three stent types of various materials, with/without coating, were evaluated. Encrustation rates were analyzed according to indwelling times and stent indication. Results: Four hundred seventy-three stents were recorded with indwelling times between 60 and 679 days. An unexpected number of long-term indwelling times were noticed: globally one-third more than 6 months, and 9% more than 1 year. In case of malignant indication, these rates were, respectively, 44% and 17%. For nonstone indication, clinically significant encrustation rates stayed extremely low before 4 months (1.3%) and quite low before 6 months (5.2%), increasing with time to reach around 10% in the long term. However, as expected, the rate was higher for stone indication with a marked increase after 4 months (8% before 4 months, nearly 17% after). Conclusion: Our data confirm a higher encrustation risk for stone patients. Long indwelling times in nonstone patients beyond 6 months or even 12 months appear to be still requested and relatively well supported in usual practice by this population.

Профилактика инкрустации и образования биопленок на поверхности мочеточникового стента (обзор литературы). Часть 2. Альтернативные материалы для изготовления внутренних дренажей. Физические методы профилактики инкрустации и формирования биопленок на поверхности мочеточниковых стентов

Introduction. Stent encrustation and formation of biofilms on its surfaces are serious medical problems, that cannot be solved without removing or replacing of the drain. Various researches are being conducted worldwide, trying to solve this problem, while a universal way of such stent complications prevention is still unreached. Aim. The aim of this study was to evaluate the effectiveness of biodegradable stents and physical methods as alternative ways to prevent drainage complications. Materials and methods. A literature search was performed of the Pubmed, Web of Sience, Science Direct, Scopus, Cyberleninka, E-library, CNMB and other databases for the period of time from 1984 to 2020 for the following keywords: ureteral stent, encrustation, biofilm, urolithiasis, bacteriuria, ultrasound. Of more than 100 studies found, 48 scientific papers, most fully correspond to the article topic, were analyzed. Results. The use of biodegradable stents eliminates a need for interventions to remove them, improving the patient's quality of life, as well as reducing the economic burden on the healthcare system. However, the problem of degradation rate control and stent degradation products elimination still exists. Conclusions. The majority of proposed physical methods of impact on a stent need a contact way of implementation, that largely hinders their clinical use. Thus, non-invasive methods seem promising and require further researches.

Ureteral Stent Microbiota Is Associated with Patient Comorbidities but Not Antibiotic Exposure

SummaryUreteral stents are commonly used to prevent urinary obstruction but can become colonized by bacteria and encrusted, leading to clinical complications. Despite recent discovery and characterization of the healthy urinary microbiota, stent-associated bacteria and their impact on encrustation are largely underexplored. We profile the microbiota of patients with typical short-term stents, as well as over 30 atypical cases (all with paired mid-stream urine) from 241 patients. Indwelling time, age, and various patient comorbidities correlate with alterations to the stent microbiota composition, whereas antibiotic exposure, urinary tract infection (UTI), and stent placement method do not. The stent microbiota most likely originates from adhesion of resident urinary microbes but subsequently diverges to a distinct, reproducible population, thereby negating the urine as a biomarker for stent encrustation or microbiota. Urological practice should reconsider standalone prophylactic antibiotics in favor of tailored therapies based on patient comorbidities in efforts to minimize bacterial burden, encrustation, and complications of ureteral stents.

Stent Encrustation due to Forgotten Double-J Stents: A Series of Five Cases

Stent Encrustation due to Forgotten Double-J Stents: A Series of Five Cases

Reduction of ureteral stent encrustation by modulating the urine pH and inhibiting the crystal film with a new oral composition: a multicenter, placebo controlled, double blind, randomized clinical trial

BackgroundEncrustation of ureteral double J stents is a common complication that may affect its removal. The aim of the proposed study is to evaluate the efficacy and safety of a new oral composition to prevent double J stent encrustation in indwelling times up to 8 weeks.MethodsA double-blinded, multicenter, placebo-controlled trial was conducted with 105 patients with indwelling double J stents enrolled across 9 public hospitals in Spain. The patients were randomly assigned (1:1) into intervention (53 patients) or placebo (52 patients) groups for 3 to 8 weeks and both groups self-monitored daily their morning urine pH levels. The primary outcome of analysis was the degree of stent ends encrustation, defined by a 4-point score (0 – none; 3 – global encrustation) using macroscopic and electron microscopy analysis of crystals, after 3 to 8-w indwelling period. Score was exponentially transformed according to calcium levels. Secondary endpoints included urine pH decrease, stent removal, and incidence of adverse events.ResultsThe intervention group benefits from a lower global encrustation rate of stent ends than placebo group (1% vs 8.2%; p < 0.018). Mean encrustation score was 85.12 (274.5) in the placebo group and 18.91 (102.27) in the intervention group (p < 0.025). Considering the secondary end points, treated patients reported greater urine pH decreases (p = 0.002). No differences in the incidence of adverse events were identified between the groups.ConclusionsOur data suggest that the use of this new oral composition is beneficial in the context of ureteral double J indwelling by decreasing mean, as well as global encrustation.Trial registrationThis trial was registered at www.clinicaltrials.gov under the name “Combined Use of a Medical Device and a Dietary Complement in Patient Urinary pH Control in Patients With an Implanted Double J Stent” with date 2nd November 2017, code NCT03343275, and URL.

A 22-Year-Old Retained Ureteral Stent: One of the Oldest Removed Using a Multimodal Endourologic Approach.

Background: Ureteral stent encrustation poses a distinct challenge to urologists. The purpose of our study is to present a patient with one of the oldest retained ureteral stents reported in the literature, effectively treated at our institution with a multimodal endourologic approach. Case Presentation: After IRB approval and patient's consent, we present the case of a 47-year-old man who was referred to our institution for gross hematuria and a right retained ureteral stent, incidentally found on imaging. This patient had a history of traumatic stab wound 22 years prior, requiring an exploratory laparotomy and a ureteral stent insertion. Preoperative CT scan revealed a fragmented and heavily encrusted right ureteral stent. The patient was effectively treated with a multimodal endourologic approach, including a cystolitholapaxy, a right retrograde flexible ureteroscopy (URS), and a prone split-leg right percutaneous nephrolithotomy combined with a right retrograde URS. The patient was rendered stone and stent free. Conclusion: To our knowledge, this 22-year-old retained stent is one of the oldest reported in the literature. As observed in our patient, multimodal endourologic techniques are safe and effective in patients with retained ureteral stents to render then stent and stone free.

A preliminary study on the role of Bacteroides fragilis in stent encrustation.

To preliminarily study the characteristics of bacterial flora distribution in the urine of ureteral stent encrustation patients as well as the relation between Bacteroides and stent encrustation. Patients undergoing ureteral stenting were included in the study and divided into encrustation group and non-encrustation group based on the condition of stent encrustation. The urine of patients was collected to undergo 16s DNA test to compare the bacterial flora distribution characteristics of the two groups. The bacterial genus with highest abundance in the urine of encrustation group was used for animal experiment. A rat model with a foreign body in the bladder was created, in which the rats were injected with the aforesaid bacterial genus. A control group injected with normal saline was also formed. The incidence of foreign body tube encrustation between the two groups was compared. The urine collected from the patients in encrustation group contained a variety of bacteria, while dominant bacteria genera included g_Lactobacillus (23.1%), g_Bacteroides (18.8%) and g_norank_Bacteroides (17.1%). While the urine from the non-encrustation group was less diverse in bacteria flora, as the major bacteria genera were g_Escherichia-Shigella (32.2%), g_Enterococcus (24.9%) and g_Pseudomonas (18.2%). Bacteroidetes in the encrustation group were significantly higher, therefore Bacteroides fragilis in this genus was adopted for animal experiment, resulting in a higher incidence of foreign body tube encrustation in the bladder among rats. The present study enriches our knowledge about ureteral stent encrustation and reveals that the target regulation of urine bacteria is worth further research and clinical application.

V04-06 ENCRUSTATED METALLIC URETERAL STENT TREATED BY MINI NEPHROLITHOTOMY

INTRODUCTION AND OBJECTIVE: The use of polymeric double J stents for the management of ureteral strictures is effective for a short period of time, although they have limited use due to the risk of obstruction and to the need for periodic stent changes. Metal stents have been developed with the aim of maintaining greater ureteric patency, alleviating symptoms, and, especially, allowing less frequent exchanges. Although metallic stent changes are approved for 12 months, there are no concrete data defining a safe dwell-time to prevent clinically significant encrustations. Likewise, there are no reports of surgeries performed to treat metal stent encrustations. Our objective with this video is to describe a case of a large metallic ureteral stent encrustation successfully treated by Mini Percutaneous Nephrolithotomy (MiniPerc) in an obese patient. METHODS: A 48-year-old female was admitted at our hospital for treatment. The patient had previously undergone a metallic DJ stent implantation for the treatment of a chronic ureteral stricture but hasn’t had a stent exchange in the last 18 months due to loss of follow-up. Radiological exams revealed a large encrustation at the right renal pelvis (2,5x1,6cm). After the attempt of removing the stent by cystoscopy failed, a mini percutaneous nephrolithotomy was performed to treat the kidney stone and to implant another stent. RESULTS: After the procedure, the patient became stone-free and had a silicone DJ stent implanted. Metabolic evaluation of the urine did not reveal hypercalciuria or any other contributing factor for this severe complication. CONCLUSIONS: Large encrustations on a metallic ureteral stent are rare complications and may require surgical treatment. Mini percutaneous nephrolithotomy seems to provide a safe and feasible treatment option for these cases, even in obese patients. Source of Funding: Authors

Radiological retrograde ureteric stent exchange in women: a single-centre review

To evaluate the safety and efficacy of modified wire loop technique for retrograde stent exchange. All patients were from the KK Women and Children's Hospital where there is no on-site urology service. Patients were identified retrospectively from the institutional radiological information system (RIS) database. In total, 270 stents were removed and 238 replaced for 79 patients between January 2012 to December 2016. Success rates for stent removal and exchange as well as skin dose and fluoroscopy time were assessed. Stent exchange was successful in 234/238 (98%) of cases. Failure was due to loss of access (one case), inability to snare stent due to distorted anatomy (two cases), and extensive encrustation of stent (one case). In 252/270 (93%) cases, stent was removed using modified snare while in 18 (7%) cases, other snare devices were used. Average fluoroscopy time per stent for stent exchange was 573 seconds and average skin dose was 12,494 DAP/mGy•cm2. Fluoroscopy-guided retrograde ureteric stent exchange using the modified snare loop technique is effective, quick, and can be performed easily with equipment used in daily intervention practice. It may also be coupled with ureteroplasty, which may help the patient achieve eventual stent-free status.

Comparison of silicone versus polyurethane ureteral stents: a prospective controlled study

BackgroundApproximately 80% of patients with indwelling ureteral stents experience stent related symptoms (SRS). We believe SRS can be reduced through altering the composition of ureteral stents to a less firm material. Therefore, we aim to compare modern silicone and polyurethane ureteral stents in terms of SRS intensity and safety.MethodsFrom June 2018 to October 2018, patients from two distinct clinical centers were prospectively enrolled in the study and stratified (non-randomly) into either control group A, patients who received polyurethane stents (Rüsch, Teleflex), or experimental group B, patients who received silicone stents (Cook Medical). Each participant completed a survey 1 h after stent insertion, in the middle of the stent dwelling period, and before stent removal or ureteroscopy noting body pain and overactive bladder via the visual analog scale pain (VASP) and overactive bladder (OAB) awareness tool, respectively. Additionally, successfulness of stent placement, hematuria, number of unplanned visits, and stent encrustation rates were assessed within each group.ResultsA total of 50 patients participated in the study, control group A consisted of 20 patients and experimental group B consisted of 30 patients. Participants in group B, silicone ureteral stents, demonstrated significantly lower mean values of VASP 2 weeks prior to stent removal and promptly before stent removal (p = 0.023 and p = 0.014, respectively). No other comparisons between the two groups were statistically significant.ConclusionsCompared to polyurethane ureteral stents, silicone ureteral stents are associated with lower body pain intensity assessed by VASP 2 weeks before stent removal and at the time of stent removal.Trial registrationCurrent Controlled Trials NCT04000178. Retrospectively registered on June 26, 2019.

Piecemeal Retrograde Removal of Encrusted and Encased Stuck Ureteral Stent: Video Tips and Tricks

Introduction: Ureteral stent encrustation leads to morbidity related to ureteral obstruction along with urinary tract infection or sepsis. The time duration it takes for stent encrustation is varia...

Comparison of ureteric stent removal procedures using reusable and single-use flexible cystoscopes following ureteroscopy and lasertripsy: a micro cost analysis.

IntroductionDiagnostic pressure on endoscopy suite can lead to delay in flexible cystoscopic stent removal. We compare the cost and organizational impact of reusable flexible cystoscope versus single-use, flexible cystoscope with a built-in stent grasper (Isiris®).Material and methodsData for the reusable cystoscopic stent removal performed in endoscopy room, group A (period 1) were compared to Isiris disposable stent removal performed in outpatient clinic, group B (period 2). We chose the same calendar months in successive years for these two different groups (9 months each). A micro cost analysis was performed evaluating the impact on costs, complications and organizational benefit.ResultsA total of 72 patients (37, group A; 35, group B) were included with no significant differences in age and gender ratio. The mean procedure time was 14.4 and 2.2 minutes, and the mean stent dwell time was 26.8 and 15.4 days in groups A and B respectively (p <0.001). In group A, 5 patients (14%) developed stent encrustation, of which 3 needed a ureteroscopic removal subsequently. No complication occurred in group B. More staff on average were needed for procedures done in group A, than group B (p <0.001).The number of patients who had cancer diagnostic wait of >2 weeks for flexible cystoscopy and the mean number of days they waited, reduced from 16 to 3, and 21 days to 3 days respectively between period 1 to period 2. The cost per procedure between group A and group B was £267.2 and £252.62 (p <0.05) if the cost of managing complications was not considered, and £365.40 and £252.62 (p <0.001) if the cost of managing complications was also considered.ConclusionsIsiris significantly reduced stent dwell time, procedural time and staff needed to carry out the stent removals. It also allowed the procedures to be done in the outpatient setting thereby reducing the organizational pressure on endoscopy related diagnostic procedures.

UP057 - Comparison of silicone versus polyurethane ureteral stents: A prospective controlled study

Approximately 80% of patients with indwelling ureteral stents experience stent related symptoms (SRS). We believe SRS can be reduced through altering the composition of ureteral stents to a less firm material. Therefore, we aim to compare modern silicone and polyurethane ureteral stents in terms of SRS intensity and safety. From June 2018 to October 2018, patients from two distinct clinical centers were prospectively enrolled in the study and stratified (non-randomly) into either control group A, patients who received polyurethane stents (Rusch, Teleflex), or experimental group B, patients who received silicone stents (Cook Medical). Each participant completed a survey 1 h after stent insertion, in the middle of the stent dwelling period, and before stent removal or ureteroscopy noting body pain and overactive bladder via the visual analog scale pain (VASP) and overactive bladder (OAB) awareness tool, respectively. Additionally, successfulness of stent placement, hematuria, number of unplanned visits, and stent encrustation rates were assessed within each group. A total of 50 patients participated in the study, control group A consisted of 20 patients and experimental group B consisted of 30 patients. Participants in group B, silicone ureteral stents, demonstrated significantly lower mean values of VASP 2 weeks prior to stent removal and promptly before stent removal (p = 0.023 and p = 0.014, respectively). No other comparisons between the two groups were statistically significant. Compared to polyurethane ureteral stents, silicone ureteral stents are associated with lower body pain intensity assessed by VASP 2 weeks before stent removal and at the time of stent removal. Current Controlled Trials NCT04000178. Retrospectively registered on June 26, 2019.

Using bespoke 3D-printed models to improve patient understanding of an encrusted ureteric stent

A 22-year-old man underwent a laparoscopic left pelvic ureteric junction obstruction repair, with a covering ureteric stent. At six weeks postoperatively, an unsuccessful attempt at stent removal was attempted because of mild calcification and patient tolerance. Removal under general anaesthetic was arranged, but the patient did not return despite multiple offered appointments, letters and correspondence. He eventually presented to the emergency department with pain and haematuria 21 months later. A computed tomography (CT) scan showed significant stent encrustation, but the patient self-discharged against medical advice. He re-presented several weeks later and was booked for an elective laser cystolithopaxy and percutaneous nephrolithotomy (PCNL) for stent removal. This was performed without complication, and the patient was discharged day two postoperatively when he was stone and stent free...

Encrustations on ureteral stents from patients without urinary tract infection reveal distinct urotypes and a low bacterial load

BackgroundCurrent knowledge of the urinary tract microbiome is limited to urine analysis and analysis of biofilms formed on Foley catheters. Bacterial biofilms on ureteral stents have rarely been investigated, and no cultivation-independent data are available on the microbiome of the encrustations on the stents.ResultsThe typical encrustations of organic and inorganic urine-derived material, including microbial biofilms formed during 3–6 weeks on ureteral stents in patients treated for kidney and ureteral stones, and without reported urinary tract infection at the time of stent insertion, were analysed. Next-generation sequencing of the 16S rRNA gene V3–V4 region revealed presence of different urotypes, distinct bacterial communities. Analysis of bacterial load was performed by combining quantification of 16S rRNA gene copy numbers by qPCR with microscopy and cultivation-dependent analysis methods, which revealed that ureteral stent biofilms mostly contain low numbers of bacteria. Fluorescence microscopy indicates the presence of extracellular DNA. Bacteria identified in biofilms by microscopy had mostly morphogenic similarities to gram-positive bacteria, in few cases to Lactobacillus and Corynebacterium, while sequencing showed many additional bacterial genera. Weddellite crystals were absent in biofilms of patients with Enterobacterales and Corynebacterium-dominated microbiomes.ConclusionsThis study provides novel insights into the bacterial burden in ureteral stent encrustations and the urinary tract microbiome. Short-term (3–6 weeks) ureteral stenting is associated with a low load of viable and visible bacteria in ureteral stent encrustations, which may be different from long-term stenting. Patients could be classified according to different urotypes, some of which were dominated by potentially pathogenic species. Facultative pathogens however appear to be a common feature in patients without clinically manifested urinary tract infection.Trial registrationClinicalTrials.gov, NCT02845726. Registered on 30 June 2016—retrospectively registered.

Endoscopic, Single-Session Management of Encrusted, Forgotten Ureteral Stents.

Background and Objectives: Remained or forgotten ureteral double-J stents may cause serious complications. Removing of an encrusted, forgotten stent can be challenging. We present our experience with heavily encrusted ureteral stents and discuss the endourologic treatment options as well as their effectivity. Materials and Methods: Eleven men and six women (mean 48.58 ± 14.48 years of age) with 18 encrusted forgotten stents (mean 16.4 ± 13.25 months of indwelling) were treated at our clinic. All patients underwent the operation after negative urine cultures were obtained. Their medical records were retrospectively reviewed and analyzed in terms of number of interventions required to remove the stent, operation time, complications, hospital stay and stone-free rate. Results: According to the Forgotten-Encrusted-Calcified (FECal) classification, the most common form of stent encrustation was grade III (64.7%) and 17.6% of the stents were fragmented. Four of 17 patients were initially treated with extracorporeal shock-wave lithotripsy. The patients required a mean of two endoscopic interventions for removing the encrusted stent and all stents were removed endoscopically in a single session. The mean operating time was 63.3 ± 41.8 minutes. Cystolithotripsy followed by ureteroscopy was the most common intervention (41.1%). Of the 17 patients, peroperative and postoperative complications were Clavien grade I in two, grade II in two and grade IIIb in one. The mean hospital stay was 1.3 ± 0.99 days. All patients were stone-free after a month of stent removal. Conclusions: The endourological removal of the encrusted forgotten stents in a single session is feasible and effective with a minimal morbidity. The treatment strategy should be to minimize the number of interventions.

Treatment of retained encrusted ureteral Double-J stent.

We conducted this study to evaluate patients with retained encrusted ureteral stents, identify the predisposing factors and present our experience in the management of such challenging problem. This prospective study was carried out in the period from May 2007 to February 2011 at the Urology and Nephrology Center, Al-Thawra General Hospital, Sana'a, Yemen. 40 patients with retained encrusted ureteric stents were treated at our center. All patients were initially evaluated with a radiographic imaging for assessment of stent encrustation and stone burden. Treatment decisions were based on the site and severity of encrustations in the renal pelvis, ureter and bladder and on our technical situation and availability of instrumentations. Multi-modal approaches ranging from extracorporeal shock wave lithotripsy (ESWL) to endourological and open urologic procedures were used to achieve stent removal. A total of 90 urological procedures were performed to render all 40 patients stent and stone free. The average duration of stent remained indwelling was 24.2 months (range 4 months -16 years). All patients were managed either by minimally or more invasive multi-modal endourological approaches. For upper coil encrustation percutaneous nephrolithotripsy was performed in eight patients, pyelolithotomy in two patients and ESWL in three patients. Encrustation of the body was treated initially by ESWL, followed by retrograde ureteroscopic manipulation in 12 patients. Lower coil encrustation was successfully managed by cystolitholapaxy in seven patients and one patient required cystolithotomy. Cystolithotomy, pyelolithotomy and ureterolithotomy were carried out in two patients. Two patients who had large burden bladder and kidney stones with loss of kidney function underwent nephrectomy and cystolithotomy. The retrieval of severely encrusted retained ureteral stent and its associated stone burden poses a real management challenge for urologists due to the need for multimodal procedures and the lack of standardized treatment plan.

Long-term outcome of JJ stent insertion for primary obstructive megaureter in children

Endoscopic stenting is an accepted treatment option for children with symptomatic or progressive primary obstructive megaureter (PROM). Here, long-term outcomes with endoscopic stenting are reviewed. Patients with PROM treated surgically over a 12-year period were identified using a prospectively maintained departmental database. Data were analysed using Microsoft Excel 2013 and unpaired t-tests through GraphPad Software QuickCalcs. Fifty-seven patients with PROM were surgically managed in the study centre from 2005 to 2017. Twenty-nine of fifty-seven patients had the stent as the primary procedure, whereas the remainder had ureterostomy, re-implantation or nephrectomy. Six patients had bilateral PROM, giving a total of 35 renal units that were fully analysed. There was 7:1 male predominance, and 20 of 29 patients (69%) were diagnosed antenatally. The median age at stent insertion was 8 months (40 days-10 years); the median prestent ureteric diameter was 19mmand the median pre-operative function on MAG3 was 44%. Cystoscopic stent insertion was feasible in all patients. The stent was left for a median of 183 days. In 9 of 35 (26%) renal units, the JJ stent was a successful sole long-term treatment, with median follow-up of 5 years and 8 months. The success rate was not different in children aged <1 year(8/22;36%) in comparison to children aged >1 year (1/13;8%), P=0.1. The remaining 26 renal units required further surgical intervention: ureteric re-implantation in 25 and nephrectomy in one. Indications for further surgery were stent complications in 11 renal units and stent failure in 15 (Table 1). Complications related to the stent were noted in 14 renal units (41%), half being stent migration. Other complications included UTIs, stent encrustation and recurrent haematuria. There was no identifiable prestent parameter, whether clinical or radiological, that could predict which patients were likely to be successfully managed solely by stent insertion. Stent insertion was never successful as a definitive procedure when the distal ureteric diameter was >12mm on the ultrasound after stent removal. Success rates with primary stenting as a sole treatment for PROM was 26%, which is less than that seen in other reports (50-66%). This may be attributed to the long-term follow-up in this study, together with the strict criteria for success. In the authors' experience, cystoscopically inserted JJ stents are of limited success as the sole treatment for PROM. In infants aged <1 year, stent insertion remains a reasonable temporising measure until the infant is old enough for a definitive procedure.

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.

A CASE OF URETERAL STENT ENCRUSTATION AFTER LAPAROSCOPIC PYELOPLASTY IN AN 11-YEAR-OLD GIRL

Stent encrustation is one of the most serious complications of using double J stents. The management of encrusted stent is challenging, especially in children. To date, only two pediatric cases of stent encrustation, at the expected timing of removal after pyeloplasty, have been reported. In this report, we present a case of ureteral stent encrustation after laparoscopic retroperitoneal pyeloplasty in an 11-year-old girl. She underwent dismembered pyeloplasty for pelvi-ureteric junction obstruction on the left side using a double J stent (6 F, 24 cm, Polaris ™ Ultra). Postoperative course was uneventful, except for mild bladder irritability and asymptomatic pyuria. Nine weeks later, an attempt to remove the stent was made under general anesthesia. This attempt was unsuccessful as the renal coil got stuck in the anastomotic position. A retrograde 6 F flexible ureteroscopy revealed an encrusted stent with calculi. After transurethral lithotripsy with a holmium: yttrium aluminum garnet (YAG) laser, the stent was extracted. Stone analysis showed struvite. At 8-months follow-up, she was stone-free and doing well with resolution of hydronephrosis.