Stents for malignant ureteral obstruction

Ultrasound-activated cilia for biofilm control in indwelling medical devices

Biofilm formation and encrustation are major issues in indwelling medical devices, such as urinary stents and catheters, as they lead to blockages and infections. Currently, to limit these effects, frequent replacements of these devices are necessary, resulting in a significant reduction in patients' quality of life and an increase in healthcare costs. To address these challenges, by leveraging recent advancements in robotics and microfluidic technologies, we envision a self-cleaning system for indwelling medical devices equipped with bioinspired ultrasound-activated cilia. These cilia could be regularly activated transcutaneously by ultrasound, generating steady streaming, which can be used to remove encrusted deposits. In this study, we tested the hypothesis that the generated streaming can efficiently remove encrustations and biofilm from surfaces. To this end, we developed a microfluidic model featuring ultrasound-activated cilia on its wall. We showed that upon ultrasound activation, the cilia generated intense, steady streaming, reaching fluid velocity up to 10 mm/s. In all our experiments, this mechanism was able to efficiently clean typical encrustation (calcium carbonate and oxalate) and biofilm found in urological devices. The generated shear forces released, broke apart, and flushed away encrusted deposits. These findings suggest a broad potential for ultrasound-activated cilia in the maintenance of various medical devices. Compared to existing methods, our approach could reduce the need for invasive procedures, potentially lowering infection risks and enhancing patient comfort.

A Predictive Model for the Risk of Procedural Failure in Retrograde Ureteral Stenting for Malignant Extrinsic Ureteral Obstruction

OBJECTIVE

To analyze the risk factors associated with procedural failure in retrograde ureteral stenting (RUS) among patients with malignant extrinsic ureteral obstruction (MEUO), and to develop a predictive model for estimating the probability of procedural failure.

METHODS

The data of 50 cases of procedural success and 50 cases of procedural failure in RUS were retrospectively collected from our hospital between 2020 and 2024. Eleven variables were recorded for each case, and univariate and multivariate logistic regression analyses were conducted to identify the optimal risk factors associated with RUS procedural failure. Based on these regression results, a nomogram was developed to calculate the failure probability. The discrimination ability of the nomogram was evaluated using receiver operating characteristic curve analysis, while an additional 20 cases of procedural success and 20 cases of procedural failure in RUS were included for validation.

RESULTS

Length of obstruction >3 cm, ureteral orifice violation, ureter invasion, and radiotherapy history were identified as the best predictors for RUS procedural failure. If the cumulative points calculated based on the nomogram exceeded 120, it indicated a substantial risk of RUS procedural failure. The nomogram was validated by the training set (Area Under Curve: 0.894) and the test set (Area Under Curve: 0.919), exhibiting exceptional predictive accuracy.

CONCLUSION

The nomogram developed in this study serves as a valuable and user-friendly tool for predicting the probability of RUS procedural failure among MEUO patients. It assists urologists and patients in choosing the optimal treatment for MEUO.

Endometriosis-associated obstructive uropathy: A case report

Endometriosis affects approximately 10% of premenopausal women, with urinary tract involvement in 1% of cases. Ureteric endometriosis is a rare, typically asymptomatic, cause of obstructive renal failure. We present the case of a 30-year-old woman with stage IV endometriosis and advanced human immunodeficiency virus presenting with acute, severe left flank pain and kidney injury. Imaging revealed severe, bilateral hydronephrosis due to extensive endometriosis deposits obstructing the urinary tract. Recurrent ureteric obstruction by infiltrating endometrial disease necessitated eight procedures (bilateral nephroureteric stent placements and nephrostomy insertions). Despite the severity of the disease surgery was successfully avoided. At the time of discharge and subsequent follow-up, the patient was clinically well with stable renal function (Creatinine 1.33-1.61 mg/dL). This case highlights the importance of considering endometriosis in the differential diagnosis of acute kidney injury in women. It demonstrates successful non-surgical management of severe ureteric disease to prevent irreversible renal damage.

Case report: A follow-up report of omental packing and drug therapy for canine prostate adenocarcinoma

Canine prostate is susceptible to diseases such as cysts, abscesses, and tumors. A 15-year-old male castrated Chinese rural dog underwent staged treatment. Preliminary diagnosis is based on examination results, including clinical symptoms (tenesmus, dysuria, frequent urination, and hematuria); hematology (elevated neutrophil count); X-rays (swelling of the prostate); ultrasound examination (less uniform echo in the prostate region, no echo effect in parenchyma); biopsy smear of prostate tissue (large number of neutrophils and rod-shaped bacteria). Therefore, the dog was preliminarily diagnosed with a prostate abscess. Antibiotic therapy was used for treatment. Three days later, the symptoms of hematuria and frequent urination did not improve, and the state was poor. The owner was advised to undergo surgical treatment-omental packing. Meanwhile, bacterial culture identification, drug sensitivity test and histopathological examination were performed. Pathological diagnosis was prostate adenocarcinoma. Subsequently, antibiotic therapy with enrofloxacin and antineoplastic maintenance therapy with mitoxantrone were administered. Six months later, the dogs were followed up, and the results showed no disease in the prostate tissue and no metastatic lesions. This is the report describing the use of omental packing for the treatment of prostate adenocarcinoma in dogs. In order to provide an important theoretical basis for the treatment of prostate cancer - omental packing into veterinary routine.

Canine Prostate Cancer: Current Treatments and the Role of Interventional Oncology

Prostate carcinoma is one of the most common cancers worldwide in men, with over 3 million men currently living with prostate carcinoma. In men, routine screening and successful treatment schemes, including radiation, prostatectomy, or hormone therapy, have allowed for high survivability. Dogs are recognized as one of the only mammals to spontaneously develop prostate neoplasia and are an important translational model. Within veterinary medicine, treatment options have historically been limited in efficacy or paired with high morbidity. Recently, less invasive treatment modalities have been investigated in dogs and people and demonstrated promise. Below, current treatment options available in dogs and people are reviewed, as well as a discussion of current and future trends within interventional treatment for canine PC.

Management of neglected and fragmented DJ stent with severe encrustation and stone: A case report

INTRODUCTION AND IMPORTANCE

DJ stents are widely used in urological procedures and interventions. One of the main problems associated with DJ stent is encrustation and stone formation. The main risk factor for Forgotten, encrusted and calcified (FECal) stent is duration of the stent placement. In addition to high index of suspicion, Imaging like U/S and CT scan are important diagnostic modality. Multiple endourologic and open procedure may be needed for management of fecal stent.

CASE PRESENTATION

This case report is to discuss a 23 years old female patient with a neglected stent after right pyelolithotomy was done 6 years back. The presence of the stent was identified incidentally after she visited local health facility for recurrent LUTS. The CT scan shows fragmented and encrusted stent with in the bladder and pelvis, stones in stent coils and isolated lower pole stone. She was managed by a procedure of cystolithotomy and right PCNL in separate sessions.

CLINICAL DISCUSSION

Common complication of DJ stent placement especially if left for long duration is encrustation, stent migration, fragmentation and stone formation. Patient or relatives unawareness about the stent placement is the most important cause for neglecting stent. Multiple Endourologic procedures may be needed for the management of FECal stent. However some resource limited settings do combination of endourologic and open surgery.

CONCLUSION

Minimizing the duration of the stent especially for patient with risk factors is advised to decrease encrustation. Since management of FECal stent is challenging both for patient and urologists, prevention is the way to tackle it. Multiple procedures may be required to manage FECal stent.

Prediction of Stent Failure for Malignant Ureteral Obstruction in Non-Urological Cancer

PURPOSE

To analyze prognostic factors associated with ureteral stent failure and to develop a prediction model for malignant ureteral obstruction (MUO) in patients with non-urological cancers.

MATERIALS AND METHODS

We retrospectively reviewed patients with non-urological cancers who underwent ureteral stenting or percutaneous nephrostomy (PCN) for MUO between 2006 and 2014. Variables predicting stent failure were identified using Cox regression analysis.

RESULTS

Of the 743 patients, 468 (63.0%) underwent ureteral stenting only, and 275 (37.0%) underwent PCN owing to technical (n=215) or functional (n=60) stent failure. The median overall survival was 4 [interquartile range (IQR) 1-11] months, and the median interval duration to stent failure was 2 (IQR 0-7) months. In univariate analysis, lower gastrointestinal cancer, previous radiotherapy to the pelvis, bladder invasion, lower ureteral obstruction, and low previous estimated glomerular filtration rate (eGFR) (<30 mL/min/1.73 m²) were significantly associated with a decreased survival rate. In multivariate analysis, bladder invasion and previous eGFR were significant predictors. With these two predictors, we divided patients into three groups based on their presence: low-risk (neither factor; n=516), intermediate-risk (one factor; n=206), and high-risk (both factors; n=21). The median stent failure-free survival rates of patients in the low-, intermediate-, and high-risk groups were 26 (8-unreached), 1 (0-18), and 0 (0-0) months, respectively (p<0.001).

CONCLUSION

In cases of ureteral obstruction caused by non-urological cancers, patients with bladder invasion and a low eGFR showed poor stent failure-free survival. Therefore, PCN should be considered the primary procedure for these patients.

Allium® ureteral stent, a new player in the treatment of ureteral stenosis: a prospective cohort study

INTRODUCTION AND OBJECTIVES

Ureteral stricture is a chronic condition that can result in the obstruction of urinary drainage from the affected renal unit, leading to loss of renal function. Treatment methods can be categorized into two main headings: endourological and reconstructive procedures. We aimed to investigate the efficacy and safety of the self-expandable Allium® ureteral stent, which has been used in the minimally invasive treatment of ureteral stenosis in recent years.

MATERIALS AND METHODS

Twenty patients who were applied Allium® ureteral stent between 2017 and 2021 included in the study. The demographic and clinical characteristics of the patients, the details of the treatments applied to the patients, the perioperative and postoperative complications, the treatments applied for the complications and the findings in the follow-up were recorded and evaluated prospectively.

RESULTS

Etiology included urolithiasis in 16 patients (80%), malignancy in 3 patients (15%), and a previous gynecological operation in 1 patient (5%). Stent obstruction was found to be the most common complication in 3 patients (15%). Stent migration was the second most common complication in 2 patients (10%). Our follow-up continues with 15 patients without stent-related complications and stent obstruction. The mean follow-up period was 28 ± 15.7 months.

CONCLUSIONS

Allium ureteral stent is an effective and reliable method in the minimally invasive treatment of ureteral stricture with complications seen at acceptable rates and ease of treatment in the management of complications.

Hydronephrosis in patients with cervical cancer: An improved stent-change therapy for ureteral obstruction Stent-change for ureteral obstruction in cervical cancer

OBJECTIVE

Ureteral stent replacement is a routine treatment for hydronephrosis in patients with cervical cancer. We developed an improved ureteral stent-change operation for hydronephrosis in cervical cancer patients and compared its outcomes with traditional stent change procedures.

STUDY DESIGN

Clinical data of hydronephrosis in cervical cancer patients who were admitted to our hospital from August 2014 to October 2019 were analyzed. We retrospectively reviewed 131 cervical cancer patients, out of which 43 cases included patients in the improved operation group, whereas 88 patients with hydronephrosis followed the traditional ureteral stent-change operation for ureteral obstruction. The outcomes of the two procedures were compared using the propensity score matching method.

RESULTS

As opposed to the traditional ureteral stent change strategy, the patients in the improved group required shorter operation time (p = 0.001) and higher success rate (p = 0.004). The FIGO stage (p = 0.046), the level of ureteral obstruction (p = 0.027), radiotherapy history (p = 0.01), stent replacement times (≤2times or > 2times) (p = 0.001), and serum creatinine level (≤200 μmol/L or > 200 μmol/L) (p < 0.001) were significantly different between the two groups before propensity score matching. Propensity score matching analysis was used to eliminate the clinical differences of 43 patients in the traditional group; however, the span of visual hematuria during the surgical complications was not included (p = 0.026) in the results.

CONCLUSION

An improved ureteral stent change operation is an advanced treatment option for cervical cancer patients suffering from hydronephrosis. In contrast to traditional ureteral stent change techniques, our developed strategy lowers complications such as visual hematuria but improves the success.

Acute kidney injury due to bilateral malignant ureteral obstruction: Is there an optimal mode of drainage?

There is a well-known relationship between malignancy and impairment of kidney functions, either in the form of acute kidney injury or chronic kidney disease. In the former, however, bilateral malignant ureteral obstruction is a surgically correctable factor of this complex pathology. It warrants urgent drainage of the kidneys in emergency settings. However, there are multiple controversies and debates about the optimal mode of drainage of the bilaterally obstructed kidneys in these patients. This review addressed most of the concerns and provided a comprehensive presentation of this topic from the recent literature. Also, we provided different perspectives on the management of the bilateral obstructed kidneys due to malignancy. Despite the frequent trials for improving the success rates and functions of ureteral stents, placement of a percutaneous nephrostomy tube remains the most recommended tool of drainage due to bilateral ureteral obstruction, especially in patients with advanced malignancy. However, the disturbance of the quality of life of those patients remains a major unresolved concern. Beside the unfavorable prognostic potential of the underlying malignancy and the various risk stratification models that have been proposed, the response of the kidney to initial drainage can be anticipated and evaluated by multiple renal prognostic factors, including increased urine output, serum creatinine trajectory, and time-to-nadir serum creatinine after drainage.

Urinary tract obstruction: Ultrasound-guided intervention

Introduction

Urinary tract obstruction (UTO) is a common clinical problem of which there are many potential causes. The aim of this feature article is to explore the role of ultrasound in diagnosing UTO, during guided interventional procedures and the potential procedural complications.Topic description and discussion: Ultrasound is an integral imaging modality throughout the management pathway of a patient with UTO and is often utilised as a first-line test in diagnosis and treatment. Percutaneous nephrostomy is an interventional technique, usually performed by radiologists or interventional sonographers, as either a short- or long-term management strategy. It can either be used in isolation or to gain access to the renal collecting system prior to more complex interventional or surgical techniques. Ultrasound-guided interventional techniques to relieve UTO can be employed in a number of clinical scenarios each with their own indications, contraindications and complications.

Conclusion

Ultrasound plays a unique role in the planning and active stages of intervention with the provision of dynamic imaging which is crucial for providing safe and effective patient management.

Incidental findings on prostate MRI: a close look at the field of view in this anatomical region

Magnetic resonance imaging (MRI) has been widely used as an advanced imaging modality to detect prostate cancer and indicate suspicious areas to guide biopsy procedures. The increasing number of prostate examinations with MRI has provided an opportunity to detect incidental lesions, and some might be very significant to elucidate patient symptoms or occult neoplastic process in the early stages. These incidental lesions might be located in the prostate gland, adjacent tissues, or organs around the prostate gland or out of the genitourinary system. The field of view of prostate MRI includes not only the prostate gland but also other critical pelvic organs in this specific anatomical region. Some of these incidental lesions might cause the same symptoms as prostate cancer and might explain the symptoms of the patient, and some might indicate early cancer stages located outside the prostate. Reporting these lesions might be life-saving by initiating early disease treatment. Awareness of the predicted locations of congenital anomalies would also be beneficial for the radiologists to mention these incidental findings.

Factors Associated with Ureteral Stent Failure in Patients with Malignant Ureteral Obstruction

Introduction: Management of malignant ureteral obstruction (MUO) with ureteral stents remains a clinical challenge, often involving frequent stent exchanges attributable to stent failure or other urological complications. We report our institutional experience with ureteral stents for management of MUO, including analysis of clinical factors associated with stent failure. Methods: We performed a retrospective review of patients treated with indwelling ureteral stents for MUO in nonurothelial malignancies at our tertiary-care institution between 2008 and 2019. Univariate Cox proportional hazards analysis was performed to identify clinical variables associated with stent failure and stent-related complications. Stent failure was defined as need for unplanned stent exchange, placement of percutaneous nephrostomy (PCN), or tandem stents. Results: In our cohort of 78 patients, the median (range) number of stent exchanges was 2 (0-17) during a total stent dwell time of 4.3 (0.1-40.3) months. Thirty-four patients (43.6%) developed a culture-proven urinary tract infection (UTI) during stent dwell time. Thirty-five patients (44.8%) had stent failure. Twenty-two patients (28.2%) underwent unplanned stent exchanges, 23 (29.5%) required PCN after initial stent placement, and 6 (7.7%) required tandem stents. Ten (28.6%) patients with stent failure were treated with upsized stents, which led to resolution in seven patients. Stent failure occurred with 20/44 (45.4%) Percuflex™, 15/27 (55.6%) polyurethane, and 2/3 (66.7%) metal stents. In patients with ≥2 exchanges (N = 45), median time between exchanges was 4.1 (2.0-14.8) months. Bilateral stenting and history of radiation predicted UTI development. Median overall patient survival after initial stent placement was 19.9 months (95% CI 16.5-37.9 months). Conclusions: Ureteral stent failure poses a significant medical burden to patients with MUO. Better methods to minimize stent-related issues and improve patient quality of life are needed. Using a shared decision-making approach, clinicians and patients should consider PCN or tandem stents early in the management of MUO.

Tumor stent for chronic ureteral obstruction: Which are predictors of stent failure?

PURPOSE

To identify predictors of UROSOFT® tumor stent failure. According to the manufacturer, this reinforced ureteral stent has a maximal dwell time of 6 months. Nonetheless, stent failure may reduce this maximal dwell time.

METHODS

All patients undergoing first-time UROSOFT® tumor stent insertion in our institution between 2010 and 2018 were considered for this retrospective analysis. Primary endpoint was stent failure and defined as premature stent exchange or percutaneous nephrostomy insertion.

RESULTS

182 patients were available for analysis. Median age was 68 years. Causes for tumor stent placement were extrinsic ureteral obstruction in 144 patients (79 %) and intrinsic obstruction in 38 patients (21 %). Tumor stent failure free survival estimates at 1, 2, 3, 4 and 5 months were 89%, 83%, 76%, 65% and 52%, respectively. Patients with stent failure had significantly higher grade of hydronephrosis, higher urinary culture bacterial growth, higher serum WBC, higher CRP and lower eGFR at the time of re-intervention, compared to patients who underwent regular stent exchange. Of all baseline and perioperative parameters, we found bilateral insertion, intrinsic ureteral obstruction, and urinary tract infection (UTI) at time of tumor stent insertion to be significant and independent predictors of stent failure (all p < 0.05).

CONCLUSION

Despite a theoretical maximal dwell time of 6 months, around 50% of all cases are subject to premature stent failure. Predictors of stent failure are bilateral insertion, intrinsic ureteral obstruction, and UTI at the time of tumor stent insertion. Preoperative antibiotic therapy may impact on stent failure rate.

Stenting of Malignant Urinary Tract Obstructions in Humans and Companion Animals

Urine retention secondary to neoplastic obstructions of the upper and lower urinary tracts is a life-threatening condition in both humans and companion animals. Stents can be placed to temporarily or permanently open obstructed urinary tract lumens and are often able to be placed using minimally invasive techniques with guidance via ultrasonography or fluoroscopy. The literature for these techniques is vast for humans and growing for companion animals. The below review provides a discussion of the principles of stenting and types of ureteral and urethral stents, as well as the techniques for placing these stents in humans and companion animals.

Self-expanding metal ureteral stent for ureteral stricture: Experience of a large-scale prospective study from a high-volume center - Cross-sectional study

BACKGROUND

The management of ureteral stricture is still a challenge for urologists. The aim of this prospective study was to assess the safety and effectiveness of self-expanding metal ureteral stents (URS) in ureteral strictures.

METHODS

We performed URS placement procedures for ureteral stricture from Jan 2019 to July 2020, and prospectively collect various data before and after the operation. A paired T test was used to compare continuous variables before and after surgery, binary logistic regression analysis was used to identify the independent risk predictors of surgical failure.

RESULTS

A total of 147 patients with 157 renal units received successful placement of URS. The mean operative time was 70.0 min. After a median follow-up time of 15 months, 73.2% (115/157) of stents were kept in situ. The most common complication was hematuria (13, 8.8%), followed by urinary tract infection (11, 7.5%) and pain (8, 5.4%). The volume of hydronephrosis (67.9 ± 34.9 VS 34.9 ± 51.1 cm³, P = 0.0001), serum creatinine level (103.0 ± 54.5 VS 93.8 ± 45.1 μmol/L, P = 0.034) and blood urea nitrogen level (6.6 ± 6.7 VS 5.4 ± 2.4 mmol/L, P = 0.032) decreased significantly at last follow up when compared with baseline. Stricture of the distal ureter was an independent risk factor for stent failure (HR 1.77, 95% CI 1.15, 2.73, P = 0.009).

CONCLUSIONS

URS was found to be safe and effective for ureteral strictures with a limited complications and good long-term results. For those who are not suitable for surgical reconstruction, the URS is an alternative management.

Clinical factors predicting ureteral stent failure in patients with external ureteral compression

Double-J stent (DJ) placement is usually the treatment of choice for relieving external compression of the ureter. However, in some cases DJ function may become impaired and a percutaneous nephrostomy (PCN) may be required. Previous studies have reported different predictive factors for choosing PCN or DJ insertion as the initial treatment. In this study, we analyzed the risk factors for DJ failure in patients with external ureteral compression. Our results showed that the patients with moderate and severe hydronephrosis (p-value = 0.0171 and 0.0249, respectively), preexisting pyuria (p-value = 0.0128), or lower ureter obstruction (p-value = 0.0305) were more prone to DJ laterality. Age was also an important predictor. Urologists should pay more attention to these patients and consider PCN as the initial treatment.

Ureteral Stent and Percutaneous Nephrostomy in Managing Malignant Ureteric Obstruction of Gastrointestinal Origin: A 10 Years’ Experience

Background: Malignant ureteral obstruction (MUO) is variable in presentation and there is no consensus on its management, especially when caused by gastrointestinal (GI) malignancies. Our aim was to describe our experience with this oncological complication. Methods: We retrospectively analyzed the outcomes of ureteral stent and nephrostomy tube (NT) positioning for GI-related MUO from 2010 to 2020. We performed descriptive analysis, survival analysis, and uni- and multi-variate analysis. Results: We included 51 patients. NT was mainly used when bladder involvement occurred and when MUO revealed an ex novo cancer diagnosis. Survival was poorer in patients with new diagnoses and in those receiving no treatment after decompression. Moreover, MUO caused by upper-GI tumors was related to shorter overall survival. Conclusions: GI tumors causing MUO should be considered of poor prognosis. Treatment decisions should be weighted accurately by both specialists and the patient.

Clinical outcomes and prognostic factors associated with internal ureteral stent placement for malignant extrinsic ureteral obstruction

PURPOSE

The optimal management of malignant extrinsic ureteral obstruction (MUO) remains unclear. It is necessary to assess the patient prognosis in deciding the adaptation of drainage of renal pelvis. In this study, we investigated the clinical outcomes after ureteral stenting for MUO and the predictive factors for overall survival in order to create a risk-stratification model.

METHODS

We retrospectively analyzed the clinical and laboratory data of 93 patients with radiologically significant hydronephrosis associated with MUO who underwent successful stent placement between May 2005 and May 2018.

RESULTS

The median survival duration after the initial stent insertion was 266 days. Of the 93 patients, 70 died, and the median interval from the first stent insertion to death was 160 days. Multivariate analysis showed that gastric cancer as the primary disease, poor performance status before stenting, and treatment after stent insertion were significant predictors of survival. According to these three factors, we stratified patients into the following four prognostic groups: no-factor (43 patients), one-factor (23 patients), two-factor (23 patients), and three-factor (4 patients) groups. This classification was effective for predicting survival, and the median survival durations in these groups were 807, 269, 44, and 12 days, respectively (p < 0.001).

CONCLUSIONS

Our stratification model of patients with a poor prognosis after ureteral stent placement for MUO may allow urologists and clinicians to identify patients who will benefit from ureteral stenting.

Nitinol thin films functionalized with CAR-T cells for the treatment of solid tumours

Micropatterned nickel titanium (commonly known as nitinol) thin films with complex designs, high structural resolution and excellent biocompatibility can be cheaply fabricated using magnetron sputtering. Here, we show that these benefits can be leveraged to fabricate micromesh implants that are loaded with tumour-specific human chimeric antigen receptor (CAR)-T cells for the treatment of solid tumours. In a mouse model of non-resectable ovarian cancer, the cell-loaded nitinol thin films spatially conformed to the implantation site, fostered the rapid expansion of T cells, delivered a high density of T cells directly to the tumour and significantly improved animal survival. We also show that self-expandable stents that were coated with T-cell-loaded films and implanted into subcutaneous tumours in mice improved the duration of stent patency by delaying tumour ingrowth. By providing direct access to tumours, CAR-T-cell-loaded micropatterned nitinol thin films can improve the effects of cell-based therapies.

Clinical application of fluoroscopic guided percutaneous antegrade ureteral stents placement for the treatment of malignant ureteral obstruction

OBJECTIVE

To investigate the clinical efficacy and safety of fluoroscopic guided percutaneous antegrade ureteral stents placement used for treatment of malignant ureteral obstruction.

METHODS

Between April 2016 and March 2018, fluoroscopic guided percutaneous ureteral stents was performed in 25 patients, including 7 patients (28%) with bilateral obstruction. The most common cancer diagnoses were cervical cancer (28%), rectal cancer (24%) and colon cancer (16%) among these patients. Clinical data were retrospectively analyzed with respect to the efficacy, safety and outcome of this treatment method.

RESULTS

Percutaneous antegrade placement of ureteral stents was performed in all cases, including 12 ureters that failed in the initial retrograde ureteral stents placement. The median stent patency time for the antegrade ureteral stents were 10.4 (95% CI: 8.3-12.6) months. The primary complications included mild flank pain and discomfort (44%), hematuria (44%), urinary tract infection (8%), bladder irritation symptoms (4%), and arterial bleeding (4%).

CONCLUSION

Fluoroscopic guided percutaneous ureteral stents placement is a safe, efficient procedure and has a high success rate in patients with malignant ureteral obstruction.

Ureteral stents for malignant extrinsic ureteral obstruction: outcomes and factors predicting stent failure

BACKGROUND

This study investigated the clinical outcomes of stent placement for malignant extrinsic ureteral obstruction (MUO) and predictive factors for stent failure.

METHODS

We retrospectively analyzed clinical data for 91 patients with radiologically significant hydronephrosis due to MUO who underwent successful stent placement. In total, 132 ureters were stented for the decompression. Factors related to stent failure were analyzed with a Cox proportional hazards model.

RESULTS

Stent failure occurred in 25 ureters in 20 patients. The median interval to failure was 63 days. The multivariate analysis showed that the significant predictors of stent failure were bladder invasion and severe hydronephrosis before the stent insertion. The patients were divided into three groups based on these two factors: low-risk (neither factor; 85 patients), intermediate-risk (one factor; 37), and high-risk (both factors; 10). The median stent failure-free survival rate at 3 months was 94.8% in the low-risk, 71.8% in the intermediate-risk and 55.6% in the high-risk group, respectively. Of the ureters with stent failure, there was successful re-replacement of internal stents in 3 low-risk, 6 intermediate-risk and no high-risk ureters. Replacement by nephrostomy was done in 2 low-risk, 5 intermediate-risk and 7 high-risk ureters.

CONCLUSION

The patients considered at low-risk could be managed without stent failure by internal stenting. However, the patients at high-risk may require the consideration of nephrostomy or other alternatives as the initial treatment. Our stratification model may allow better risk stratification for patients with regard to ureteral stenting, helping to identify patients for whom ureteral stenting is indicated.

Metallic Ureteric Stents in Malignant Ureteric Obstruction: A Systematic Review

The effectiveness of metallic stents in the management of malignant ureteric obstruction is unclear. This systematic review evaluates the use of 4 commercially available metallic stents (Resonance, Memokath 051, Uventa, and Allium URS). Twenty-one studies met eligibility criteria. Overall success rates ranged from 88% for the Allium stent to 65% for Memokath 051. Resonance demonstrated the lowest migration rate (1%). Uventa had the lowest obstruction rate (6%). Metallic ureteric stents offer a viable alternative in the management of malignant ureteric obstruction. Further high quality studies are required to assess cost effectiveness and refine specific indications based on etiology and level of the ureteric obstruction.

The Memokath-051 Stent for the Treatment of Ureteric Obstruction: A NICE Medical Technology Guidance

Memokath-051 is a thermo-expandable, nickel-titanium alloy spiral stent used to treat ureteric obstruction resulting from malignant or benign strictures. The National Institute for Health and Care Excellence (NICE) selected Memokath-051 for evaluation. The company, PNN Medical, claimed Memokath-051 has clinical superiority and cost savings compared with double-J stents. It identified five studies reporting clinical evidence on Memokath-051 and constructed a de novo cost model comparing Memokath-051 to double-J stents. Results indicated that Memokath-051 generated cost savings of £4156 per patient over 2.5 years. The External Assessment Centre (EAC) critiqued the company's submission and completed substantial additional work. Sixteen studies were identified assessing Memokath-051 and all listed comparators in the scope (double-J stents, reconstructive surgery and metallic and alloy stents) except nephrostomy. Similar success rates were reported for Memokath-051 compared with double-J and Resonance stents and worse outcomes compared with other options with evidence available. The EAC updated the company's cost model structure and modified several inputs. The EAC's model estimated that Memokath-051 generated savings of at least £1619 per patient over 5 years compared with double-J stents, was cost neutral compared with other metallic stents and was cost saving compared with surgery up to month 55. Overall, Memokath-051 is likely to be cost saving in patients not indicated for reconstructive surgery and those expected to require a ureteral stent for at least 30 months. The Medical Technologies Advisory Committee (MTAC) reviewed the evidence and supported the case for adoption, issuing partially supportive recommendations published after public consultation as Medical Technologies Guidance 35.