Ureteric stents: Overview of current clinical applications and economic implications

Recent developments in ureteral stent: Substrate material, coating polymer and technology, therapeutic function

The ureteral stent is an effective treatment for clinical ureteral stricture following urological surgery, and the functional coating of the stent could effectively inhibit bacterial colonization and other complications. The present review provides an analysis and description of the materials used in ureteral stents and their coatings. Emphasis is placed on the technological advancements of functional coatings, taking into consideration the characteristics of these materials and the properties of their active substances. Furthermore, recent advances in enhancing the therapeutic efficacy of functional coatings are also reviewed. It is anticipated that this article will serve as a valuable reference providing insights for future research development on new drug-loaded ureteral stents.

A case report on the management of neglected and forgotten DJ stent for 18 years with severe encrustation and giant bladder stone

Ureteral stents play a vital role in urologic surgeries, aiding in urinary flow maintenance, obstruction alleviation and facilitating healing. However, when stents are forgotten, they can lead to encrustation, resulting in significant patient morbidity and posing challenges for urologists Stent-related complications have been shown to increase with the duration of time the stent is left in place. This report details the clinical presentation, diagnostic process, and treatment of a 68-year-old male patient had a neglected stent placed 18 years ago after extracorporeal shockwave lithotripsy. He presented with severe stent encrustation, a solitary giant bladder stone, and renal stones. The patient underwent a cystolithotomy to remove the bladder stone followed by an ultrasound-guided percutaneous nephrolithotomy with pneumatic lithotripsy in a separate procedure. Preventive strategies such as implementing a stent registry, enhancing patient education, and encouraging follow-up appointments are crucial to avoid such complications.

Outcomes of a non-randomised audit of single pigtail suture stents in urolithiasis management of Asian patients in Singapore

Objective

Double-J (DJ) ureteric stents are commonly placed perioperatively for semirigid or flexible ureteroscopic renal surgery. It is believed that lesser stent material within the bladder mitigates stent-related symptoms. This study aimed to evaluate the J-Fil ureteral stent, a single pigtail suture stent compared with conventional DJ stent in relation to stent symptoms in an Asian population undergoing ureterorenal intervention.

Methods

Based on internal audit committee recommendation approval, the records of 50 patients retrieved, available data of 41 patients who were prospectively enrolled into two groups (Group 1 [J-Fil stent group], n=21 and Group 2 [DJ stent group], n=20) between August 2020 to January 2021, were analysed. Parameters compared were nature of procedure, stone location and size, ease of deployment or removal, and complications. A modified universal stent symptom questionnaire was used to assess morbidity of stent symptoms within 48 h of insertion and at removal.

Results

Both groups had similar median age, distribution in male to female ratio, and stone size. The overall median universal stent symptom questionnaire score at insertion was similar for bladder pain, flank or loin pain, and quality of life between Group 1 and 2; however, at removal Group 1 fared significantly better than Group 2, especially for flank or loin pain and pain at voiding. Both groups had similar ease in insertion with no hospital readmissions.

Conclusion

Our audit favoured the single pigtail suture stent in Asian ureters in mitigating stent-related issues. It showed a good safety profile with easy deployment and removal. It promises a new standard in stenting.

Forgotten ureteral stents: a systematic review of literature

BACKGROUND

The forgotten ureteral stents (FUS) is one of the late complications of stent placement. This systematic review summarized different aspects of FUS and focused on the problems and solutions related to FUS.

METHODS

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. PubMed® and Embase® were searched from inception until October 1st, 2022. Eligible studies were those defining FUS as a stent unintentionally left in situ longer than at least 2 months.

RESULTS

Total 147 studies with 1292 patients were finally included. The mean indwelling time of FUS was 33.5 months (range from 3 months to 32 years). The most common initial cause for stent placement was adjunct treatment to urolithiasis (79.2%). The major forgetting reasons were patient-related (83.9%), which included poor compliance, lapse in memory, and misconceptions about the necessity of timely removal. Primary presenting complaints were flank pain (37.3%), lower urinary tract symptoms (33.3%), and hematuria (22.8%). Encrustation (80.8%) and urinary tract infections (40.2%) were the most common complications detected in patients with FUS. Computed tomography evolving as a preferred imaging test (76.1%) was indispensable for evaluating encrustation, migration, fracture and other complicated situations in patients with FUS. Besides, evaluation of kidney function and infection status was also of great importance. Multiple and multimodal procedures (59.0%) were often necessitated to achieve the stent-free status, and were mostly endoscopic procedures. Cystoscope was most commonly used (64.8%). Retrograde ureteroscopy (43.4%) and antegrade stent removal (31.6%) were often used when dealing with more complicated situations. Extracorporeal shockwave lithotripsy (30.4%) was often used as adjunctive to other endoscopic procedures, but it sometimes failed. The decision regarding the choice of treatment is based on the volume and site of encrustation, the direction of migration, the site of fracture, kidney function and other urinary comorbidities.

CONCLUSIONS

FUS not only pose hazard to patients' health, but also impose a huge economic burden on medical care. Thorough preoperative evaluation is fundamental to developing the treatment strategy. The management of FUS should be individualized using different treatment modalities with their advantages to minimize patients' morbidities. Prevention is better than cure. Strengthening health education and setting a tracking program are of great importance to the prevention of FUS.

Stent Syndrome: Does the Diameter Matter? Results of a Randomized Trial

Introduction: Double-J (DJ) ureteral stents are used for multiple purposes in urology. Even though they temporize the subsequent treatment of lithiasis, they may cause different symptoms that impact quality of life (QoL). Purpose: In this randomized trial, we assessed whether the diameter of ureteral stents has an impact on catheter-associated symptoms, and their impact on QoL. Methods: A total of 194 consecutive patients undergoing DJ insertion between December 2018 and December 2022 were prospectively enrolled and divided into three categories: 4.7F (Group 1, n = 71), 6F (Group 2, n = 65), and 7F (Group 3, n = 58). Within 1 week after the DJ placement, patients completed the validated Spanish version of the Ureteral Stent Symptoms Questionnaire. Continuous variables were compared using analysis of variance and Student's t-tests. For categorical data, the chi-square test was used. Results: In the domain of "work" and "additional problems," there were significant differences. In the "Work" domain, Group 1 presented the lower symptoms. In the domain "additional problems," patients in Group 1 were prescribed fewer antibiotics owing to low urinary tract symptoms. In question U4 about urinary incontinence, patients in Groups 2 and 3 developed these symptoms more than patients in Group 1. In the "sexual activity" domain, specifically in question S3 (the patient has ever suffered any type of pain during sexual activity?), patients with 4.7F presented lower scores than patients with larger catheters. Conclusion: DJ-related symptoms affect QoL in most cases. Smaller catheters produced significantly less urinary incontinence, faster work reincorporation, fewer symptoms related to sexual activity, and fewer catheter-related symptoms than 7F catheters. In contrast, Group 3 presented fewer outpatient visits because of symptoms related to the DJ.

Double J Stents and Reno-Ureteral Lithiasis: Dynamic Changes in Management during the COVID-19 Pandemic

PURPOSE

To provide an evidence-based review of the use of ureteral stents in managing reno-ureteral lithiasis during the COVID-19 pandemic.

MATERIALS AND METHODS

A literature search was conducted between 2020 and 2023 using the PubMed and SCOPUS databases. As a part of the search query, we entered "ureteral stents" OR "double J stent" AND "renal colic" OR "ureteral obstruction" OR "reno-ureteral lithiasis" AND "COVID-19 Pandemic" OR "SARS-CoV-2 infection".

RESULTS

Patients with lithiasis should be categorized into low priority, intermediate priority, high priority, and emergency under the COVID-19 pandemic scenario to manage their delay and save resources, including healthcare professionals, beds, and ventilators. However, immediate interventions are necessary for individuals at risk of life-threatening septic complications. During the COVID-19 pandemic, the feasibility of conducting or resuming elective activity depended on local circumstances, the accessibility of beds and ventilators, and the execution of screening protocols. If lithiasis surgery is delayed, consequences and increased effort will be inevitable. It is possible that teleconsultation could help guide these patients and cut down on unnecessary visits and exposure.

CONCLUSIONS

COVID-19 has shifted treatment options for urinary stones, with ureteral stents being a safe, efficient, and cost-effective option for managing urolithiasis. Decompression is essential in emergency situations, while ureteral stents reduce the risk of infection and hospital visits.

Distal end of a ureteral double-J stent displaced into the contralateral ureter after percutaneous nephrolithotripsy: a case report

We report displacement of the distal end of a ureteral double-J stent into the contralateral ureter after percutaneous nephrolithotripsy (PCNL) in a 71-year-old man with a history of left kidney stones. Postoperative computed tomography imaging showed that the distal end of the left ureteral double-J stent was displaced into the right ureter, which resulted in persistent right renal colic when the nephrostomy tube was clipped and continuous urine leakage from the nephrostomy opening after the nephrostomy tube was removed. After the cystoscopic adjustment of the ureteral stent, the patient recovered uneventfully and was discharged home the next day.

Research on the Current Application Status of Magnesium Metal Stents in Human Luminal Cavities

The human body comprises various tubular structures that have essential functions in different bodily systems. These structures are responsible for transporting food, liquids, waste, and other substances throughout the body. However, factors such as inflammation, tumors, stones, infections, or the accumulation of substances can lead to the narrowing or blockage of these tubular structures, which can impair the normal function of the corresponding organs or tissues. To address luminal obstructions, stenting is a commonly used treatment. However, to minimize complications associated with the long-term implantation of permanent stents, there is an increasing demand for biodegradable stents (BDS). Magnesium (Mg) metal is an exceptional choice for creating BDS due to its degradability, good mechanical properties, and biocompatibility. Currently, the Magmaris® coronary stents and UNITY-BTM biliary stent have obtained Conformité Européene (CE) certification. Moreover, there are several other types of stents undergoing research and development as well as clinical trials. In this review, we discuss the required degradation cycle and the specific properties (anti-inflammatory effect, antibacterial effect, etc.) of BDS in different lumen areas based on the biocompatibility and degradability of currently available magnesium-based scaffolds. We also offer potential insights into the future development of BDS.

Relationship between Urinary Parameters and Double-J Stent Encrustation

(1) Background: This study aimed to determine the relationship between metabolic urine conditions and the formation, severity, and composition of encrustations in ureteral stents. (2) Methods: Ninety stone-former patients requiring a double-J stent were prospectively enrolled. We collected 24 h metabolic urine samples and demographic data, including indwelling time and previous stone composition. The total deposit weight was obtained, and a macroscopic classification according to the degree of encrustation (null, low, moderate, and high) was created, allowing for intergroup comparisons. Stereoscopic and scanning electron microscopy were performed to identify the type of embedded deposits (calcium oxalate, uric acid, and infectious and non-infectious phosphates). (3) Results: In total, 70% of stents were encrusted; thereof, 42% had a moderate degree of encrustation. The most common encrustation type was calcium oxalate, but infectious phosphates were predominant in the high-encrustation group (p < 0.05). A direct correlation was observed between the purpose-built macroscopic classification and the encrustation weights (p < 0.001). Greater calciuria, uricosuria, indwelling time, and decreased diuresis were observed in stents with a higher degree of encrustation (p < 0.05). The urinary pH values were lower in patients with uric acid encrustations and higher in those with infectious phosphate encrustations (p < 0.05). When compared to non-encrusted stents, patients with calcium-oxalate-encrusted stent showed greater calciuria, phosphaturia, indwelling time, and reduced diuresis; patients with uric-acid-encrusted stent showed greater uricosuria; and patients with infectious and non-infectious phosphate encrustation showed greater urinary pH (p < 0.05). (4) Conclusions: Metabolic urine conditions play a critical role in the formation, composition, and severity of double-J stent encrustation.

Effect of ureteral stent length and implantation position on migration after implantation

BACKGROUND

Ureteral obstruction is a urinary system disease that causes urinary retention, renal injury, renal colic, and infection. Ureteral stents are often used for conservative treatment in clinics, and their migration usually results in ureteral stent failure. The migrations include proximal migration to the kidney side and distal migration to the bladder side, but the biomechanism of stent migration is still unknown.

METHOD

Finite element models of stents with lengths from 6-30 cm were developed. The stents were implanted into the middle of the ureter to analyze the effect of stent length on its migration, and the effect of stent implantation position on 6-cm-long stent migration was also observed. The stents' maximum axial displacement was used to assess the ease of stent migration. A time-varying pressure was applied to the ureter outer wall to simulate peristalsis. The stent and ureter adopted friction contact conditions. The two ends of the ureter were fixed. The radial displacement of the ureter was used to evaluate the effect of the stent on peristalsis.

RESULTS AND DISCUSSION

The maximum migration occurs in the positive direction for a 6-cm-long stent implanted at the proximal ureter (CD and DE), but in the negative direction at the distal ureter (FG and GH). The 6-cm-long stent demonstrated almost no effect on ureteral peristalsis. The 12-cm-long stent diminished the radial displacement of the ureter from 3-5 s. The 18-cm stent diminished the radial displacement of the ureter from 0-8 s, and the radial displacement within 2-6 s was weaker than other time. The 24-cm stent diminished the radial displacement of the ureter from 0-8 s, and the radial displacement within 1-7 s was weaker than other time.

CONCLUSION

The biomechanism of stent migration and ureteral peristalsis weakening after stent implantation was explored. Shorter stents were more likely to migrate. The implantation position had less influence on ureteral peristalsis compared with the stent length, which provided a reference for stent design aimed at reducing stent migration. Stent length was the main factor affecting ureteral peristalsis. This study provides a reference for the study of ureteral peristalsis.

Detection of microbial biofilms inside the lumen of ureteral stents: two case reports

BACKGROUND

We report large biofilm structures that covered almost the entirety of the lumen and surface of double-J stents in two postrenal transplant patients, with no development of urinary tract infection. Biofilm bacteria of one patient were integrated by coccus in a net structure, whereas overlapping cells of bacilli were present in the other patient. To the best of our knowledge, this is the first time that high-quality images of the architecture of noncrystalline biofilms have been found inside double-J stents from long-term stenting in renal transplant recipients.

CASE PRESENTATION

Two renal transplant recipients, a 34-year-old male and a 39-year-old female of Mexican-Mestizo origin, who underwent a first renal transplant and lost it due to allograft failure, had a second transplant. Two months after the surgical procedure, double-J stents were removed and analyzed using scanning electron microscopy (SEM). None of the patients had an antecedent of UTI, and none developed UTI after urinary device removal. There were no reports of injuries, encrustation, or discomfort caused by these devices.

CONCLUSION

The bacterial biofilm inside the J stent from long-term stenting in renal transplant recipients was mainly concentrated on unique bacteria. Biofilm structures from the outside and inside of stents do not have crystalline phases. Internal biofilms may represent a high number of bacteria in the double-J stent, in the absence of crystals.

Economic burden of complicated ureteral stent removal in patients with kidney stone disease in the USA

Aim: To examine the medical costs of simple versus complicated ureteral stent removal. Materials & methods: We included adults with kidney stones undergoing simple or complicated cystoscopy-based stent removal (CBSR) post ureteroscopy from the 2014 to 2018 Merative™ MarketScan^® Commercial Database. The medical costs of patients with complicated and simple CBSR were compared. Results: Among 16,682 patients, 2.8% had complicated CBSR. Medical costs for patients with complicated CBSR were higher than for simple CBSR ($2182 [USD] vs $1162; p < 0.0001). Increased stenting time, increased age, southern US geography and encrusted stent diagnoses were significantly associated with complicated CBSR. Conclusion: Complicated ureteral stent removal doubled the medical costs associated with CBSR. Ureteral stents with anti-encrustation qualities may reduce the need for complicated CBSR and associated costs.

A misplacement of a ureteral stent into the abdominal aorta: a case report of a rare retrograde ureteral stenting complication

Background

Cervical cancer is often associated with malignant ureteral obstruction and consequent hydronephrosis. Hydronephrosis caused in this way can be resolved by placing ureteral stents or performing a percutaneous nephrostomy. Complications that may occur during the retrograde ureteral stent placement are usually mild, but serious complications such as stent migration into the cardiovascular system are also possible. Here we present an unusual case where a ureteral stent entered the abdominal aorta during the cystoscopic ureteral stenting, which was resolved by a cystoscopic stent removal kept in check by endovascular catheters.

Case presentations

The 48-year-old female patient was treated in the regional secondary healthcare facility due to bilateral hydronephrosis caused by cervical cancer. The patient had bilateral percutaneous nephrostomies and ureteral stents. Due to the calcification of the left ureteral stent, an urethrorenoscopy with lithotripsy of the calculus in the left ureter was performed in the regional secondary healthcare facility, and the ureteral stent was cystoscopically replaced. The control radiography of the urinary tract showed a misplacement of the left ureteral stent, and a computed tomography showed that the stent was located in the abdominal aorta. The patient was referred to the University Clinical Center of Serbia, where a ureteral stent was cystoscopically removed from the abdominal aorta under the control of endovascular catheters. The patient was in good general condition at all times, with no signs of bleeding, and she was discharged from the hospital on the fourth postoperative day.

Conclusions

The migration of a ureteral stent into the abdominal aorta and the cardiovascular system in general is a rare type of ureteral stenting complication whose treatment requires a multidisciplinary approach. In order to prevent such complications, it is necessary to strictly adhere to the indications for the ureteral stent placement in the case of malignant ureteral obstruction. Also, this procedure should be performed according to the current guidelines and controlled by an X-ray or ultrasound.

In vitro and in vivo studies on bacteria and encrustation resistance of heparin/poly-L-lysine-Cu nanoparticles coating mediated by PDA for ureteral stent application

Ureteral stents are commonly utilized as a medical device to aid the flow of urine. However, biofilm formation and encrustation complications have been clinical problems. To overcome this challenge, heparin/poly-L-lysine-copper (Hep/PLL-Cu) nanoparticle was immobilized on a dopamine-coated polyurethane surface (PU/NPs). The stability and structural properties of the nanoparticles were characterized by Zeta potential, poly dispersion index, transmission electron microscopy, atom force microscopy and contact angle. The surface composition, antibacterial potency, encrustation resistance rate and biocompatibility of PU/NPs were investigated by scanning electron microscope, X-ray photoelectron spectroscopy, antibacterial assay and MTS assay, respectively. In addition, the anti-encrustation property was studied by implanting coated NPs stents in the rat bladder for 7 days. It was shown that the size and distribution of Hep/PLL-Cu nanoparticles were uniform. PU/NPs could inhibit Proteus mirabilis proliferation and biofilm formation, and exhibit no cytotoxicity. Less encrustation (Ca and Mg salt) was deposited both in vitro and in vivo on samples, demonstrating that the NPs coating could be a potential surface modification method of ureteral material for clinical use.

The Whiston Snare Technique for Loop Extraction of Stents (WHISTLES): A novel technique for the intraureteric assembly of a loop snare for the retrograde extraction of a migrated ureteric stent

Background:

While ureteric stent removal remains a frequently performed endourological procedure stent migration either proximally or distally can present the endourologist with a significant intraoperative dilemma. In cases where the stent is of large calibre or impacted into the mucosa of the ureter, retrieval may prove refractory to traditional approaches.

Objective:

To present a further novel procedure: The Whiston Snare Technique for Loop Extraction of Stents (WHISTLES) which allows for intraureteric assembly of a tightening loop through a ureteric catheter thus permitting safe retrieval of a migrated stent.

Methods:

We describe the procedure as it was performed and have recreated the steps in a laboratory environment. This demonstrates an adaptation of existing materials readily found in most urological theatres and is not a prototypical device.

Results:

The procedure was successfully performed to allow extraction of the migrated ureteric stent.

Conclusion:

WHISTLES is a reproducible method for the retrieval of migrated ureteric stents where traditional techniques have failed.

Level of evidence:

5

Evaluation of Selected Properties of Sodium Alginate-Based Hydrogel Material—Mechanical Strength, μDIC Analysis and Degradation

The search for ideal solutions for the treatment of urethral stenosis continues. This includes developing the material, design, while maintaining its optimal and desired properties. This paper presents the results of the research conducted on sodium alginate-based hydrogel material (AHM), which may be used as a material for stents dedicated to the treatment of pathologies occurring in the genitourinary system. In order to determine the selected parameters of the AHM samples, strength and degradation tests, as well as analysis of the micro changes occurring on the surface of the material using a digital image correlation (µDIC) system, were performed. This study shows that the material possessed good mechanical strength parameters, the knowledge of which is particularly important from the point of view of the stent-tissue interaction. The degradation analysis performed showed that the AHM samples degrade in an artificial urine environment, and that the degradation time mainly depends on the chemical composition of the material. The novel µDIC method performed allowed us to characterize the homogeneity of the material structure depending on the cross-linking agent used.

Are All Stent Bearers Equal? Ureteral Stent Symptoms in Kidney Transplant Patients: A Case-Control Prospective Study

Purpose: The aim of this study is to conduct a prospective, controlled single-center study to determine the prevalence and types of ureteral stent symptoms in kidney transplant (KTx) recipients and compare them with nontransplant subjects. Materials and Methods: From December 2012 to June 2019, a total of 102 patients having undergone a KTx and Double-J stent (DJS) placement and 88 patients having undergone endourological lithotripsy and DJS placement were enrolled. The Ureteral Stent Symptom Questionnaire (USSQ) was administered to patients with a median of 25 (KTx) and 31 (urolithiasis) days after stent placement. USSQ scores were used to compare symptoms between the two groups. Results: Of the 190 patients enrolled, 88 belonged to the lithotripsy group (control group) and 102 to the KTx recipients' group. Mean score for urinary symptoms was 21.42 for KTx patients vs 27.53 for control patients with statistical significance (p < 0.001, CI -7.792 to -4.433). The visual analog scale, overall bother, pain at voiding, flank pain at voiding, and frequency of painkiller use scores were significantly higher for control patients than for KTx patients (p = 0.024, <0.001, <0.001, <0.001, and 0.014, respectively). Frequency of rest, changes in work duration, work domain score, suspicion of urinary tract infection (UTI), and need for professional assistance scores were significantly lower for KTx patients than the control. There were no significant differences in general health and sexual domains between groups. Conclusions: KTx recipients have significantly fewer urinary symptoms, pain, work-related disturbances, suspected UTIs, and hospitalizations associated with stent placement than urolithiasis patients.

Fluid mechanical modeling of the upper urinary tract

The upper urinary tract (UUT) consists of kidneys and ureters, and is an integral part of the human urogenital system. Yet malfunctioning and complications of the UUT can happen at all stages of life, attributed to reasons such as congenital anomalies, urinary tract infections, urolithiasis and urothelial cancers, all of which require urological interventions and significantly compromise patients' quality of life. Therefore, many models have been developed to address the relevant scientific and clinical challenges of the UUT. Of all approaches, fluid mechanical modeling serves a pivotal role and various methods have been employed to develop physiologically meaningful models. In this article, we provide an overview on the historical evolution of fluid mechanical models of UUT that utilize theoretical, computational, and experimental approaches. Descriptions of the physiological functionality of each component are also given and the mechanical characterizations associated with the UUT are provided. As such, it is our aim to offer a brief summary of the current knowledge of the subject, and provide a comprehensive introduction for engineers, scientists, and clinicians who are interested in the field of fluid mechanical modeling of UUT. This article is categorized under: Cancer > Biomedical Engineering Infectious Diseases > Biomedical Engineering Reproductive System Diseases > Biomedical Engineering.

Intrathoracic ureteric stent migration through a reno-pleural fistula: a case report of rare antegrade ureteric stenting complication

BACKGROUND

Malignant obstruction and associated hydronephrosis is a common complication of advanced cervical cancer. Percutaneous nephrostomy (PCN) followed by antegrade stenting is often required to relieve obstruction as retrograde access fails in considerable proportion of such patients. Reno-pleural fistula is a rare complication of PCN which creates a patent connection between the renal collecting system and the thoracic cavity, and urine accumulation in the pleural space can cause pleural effusion (i.e., urinothorax). Upward or downward migration is a complication of indwelling ureteric stents. Further migration with extrusion outside of the urinary tract is uncommon. Herein we present an unprecedented case in adult of ureteric stent upward migration through a reno-pleural fistula into the thoracic cavity managed by thoracoscopy.

CASE PRESENTATION

A 66-year-old female was diagnosed of advanced stage cervical cancer with suspicious bladder invasion. Given her bilateral hydronephrosis with impaired renal function, she underwent bilateral PCN and subsequent antegrade ureteric stenting. However, she presented with dyspnea, right back pain, and oliguria four days after bilateral PCN catheter removal. Computed tomography reported massive right pleural effusion and an intrathoracic ureteric stent within reno-pleural fistula. Thoracoscopy with thoracostomy was performed to remove the ureteric stent and urine in right pleural space. A week later, urinothorax had resolved and right PCN was performed again. She was discharged after regaining normal renal function with right PCN and a left ureteric stent in place.

CONCLUSIONS

A reno-pleural fistula can serve as a route for ureteric stent migration and that continuous drainage of urine can cause urinothorax once the stent reaches the thoracic cavity. Anytime a supracostal approach is used for PCN, even when using small caliber catheters, clinicians should pay special attention given the risk of pleural injury and subsequent complications.

Outcomes and Cost Evaluation Related to a Single-Use, Disposable Ureteric Stent Removal System: a Systematic Review of the Literature

PURPOSE OF REVIEW

To present the latest evidence related to the outcomes and cost of single-use, disposable ureteric stent removal system (Isiris).

RECENT FINDINGS

Our review suggests that compared to a reusable flexible cystoscope (re-FC), a disposable flexible cystoscope (d-FC) with built-in grasper (Isiris) significantly reduced procedural time and provided a cost benefit when the latter was used in a ward or outpatient clinic-based setting. The use of d-FC also allowed endoscopy slots to be used for other urgent diagnostic procedures. Disposable FCs are effective and safe for ureteric stent removal. They offer greater flexibility and, in most cases, have been demonstrated to be cost-effective compared to re-FCs. They are at their most useful in remote, low-volume centres, in less well-developed countries and in centres where large demand is placed on endoscopy resources.

Innovations in urolithiasis management

PURPOSE OF REVIEW

This review provides a forecast about ongoing developments in the management of urolithiasis with a potential to challenge the current standard of care. We therefore emphasized innovative technology, which might be considered still experimental in the daily clinic or needs further clinical validation, but harbors the great potential to become a game changer for future stone management.

RECENT FINDINGS

Especially in the endoscopic stone treatment, we observed a multitude of groundbreaking technical innovations, which changed our treatment algorithms over the last decades. Some of this technology already found its way into daily practice. Others like artificial intelligence, burst wave lithotripsy, smart laser systems or gene therapy may not be standardized yet, but have the potential to further revolutionize current practice. Besides those technical features, we included innovations in prevention and diagnostics, as well as patient expectations and patient satisfaction into the analysis. A proper metaphylaxis and patient communication seems to be essential for a long-lasting treatment success.

SUMMARY

The combination of technical innovations, improved stone metaphylaxis and proper patient communication presents the cornerstone of future kidney stone management.

Pigtail Suture Stents Significantly Reduce Stent-related Symptoms Compared to Conventional Double J Stents: A Prospective Randomized Trial

Background

Double J (DJ) ureteral stents are commonly inserted after ureteroscopy (URS) procedures for stone treatment. However, stent-related symptoms are still a major issue.

Objective

To determine whether a commercially available pigtail suture stent (PSS) can reduce stent-related symptoms compared to a conventional DJ stent after uncomplicated URS.

Design setting and participants

We designed a randomized, single-blind, parallel-group trial from January to November 2020. The inclusion criteria were stone-free URS without intraprocedural complications. Patients with distal ureteral stones were excluded.

Intervention

Insertion of a PSS or DJ stent after URS.

Outcome measurements and statistical analysis

The primary endpoint was the Urinary Symptom Index score on the Ureteral Stent Symptoms Questionnaire (USSQ) 2 wk after URS. Secondary endpoints were USSQ domain scores and responses to individual USSQ questions at 2 d and 2 wk after surgery.

Results and limitations

A total of 78 patients were randomized and treated according to protocol. The Urinary Symptom Index score (p = 0.004), overall Visual Analogue Scale (VAS) score (p = 0.022), and the percentage of patients complaining of pain (63.9% vs 86.1%, p = 0.029) were significantly in favor of PSS at both 2 d and 2 wk after URS. At 2 d, the VAS score among patients with pain (p = 0.025) and the General Health Index score (p = 0.036) were significantly better in the PSS group. No severe complications occurred in either group. Study limitations are the exclusion of patients with distal ureteral stones and the limited sample size.

Conclusions

PSS significantly reduced stent-related symptoms after URS, in particular urinary symptoms and pain, compared to conventional DJ stents, and showed a good safety profile.

Patient summary

Stents are hollow tubes placed in the passage between the kidney and the bladder (ureter). The standard stent has two coiled ends (double J stent) to keep it in place in both the kidney and the bladder. We tested a commercial stent with two strings at the bladder end (pigtail suture stent) after procedures to remove stones from the upper urinary tract and found that it caused less stent-related symptoms compared to a double J stent.

This trial is registered at Clinicaltrials.gov as NCT03344120.

Comparative assessment of biodegradable-antireflux heparine coated ureteral stent: animal model study

BACKGROUND

Double J ureteral stents are widely used on urological patients to provide drainage of the upper urinary tract. Unfourtunately, ureteral stents are not free from complications, as bacterial colonization and require a second procedure for removal. The purpose of the current comparative experimental study is to evaluate a new heparin-coated biodegradable antireflux ureteral stent (BraidStent®-H) to prevent urinary bacterial colonization.

METHODS

A total of 24 female pigs were underwent determination of bacteriuria and nephrosonographic, endoscopic and contrast fluoroscopy assessment of the urinary tract. Afterward, were randomly assigned animals to Group-I, in which a 5Fr double-pigtail ureteral stent was placed for 6 weeks, or Group-II, in which a BraidStent®-H was placed. Follow-up assessments were performed at 1, 3, 6, 8, 12 weeks. The final follow-up includes the above methods and an exhaustive pathological study of the urinary tract was accomplished after 20 weeks.

RESULTS

Bacteriuria findings in the first 48 h were significant between groups at 6 h and 12 h. Asymptomatic bacteriuria does not reach 100% of the animals in Group-II until 48 h versus Group-I where it appears at 6 h. The weekly bacteriuria mean rate was 27.7% and 44.4% in Group I and II respectively, without statistical significance. In Group II there were no animals with vesicoureteral reflux, with statistical significance at 3 and 6 weeks with Group-I. The 91.2% of stents in Group-II were degraded between 3 and 6 weeks, without obstructive fragments. Distal ureteral peristalsis was maintained in 66.6-75% in Group-II at 1-6 weeks.

CONCLUSIONS

The heparin coating of BraidStent® allows an early decrease of bacterial colonization, but its effectiveness is low at the long term. Heparin coating did not affect scheduled degradation rate or size of stents fragments. BraidStent®-H avoids the side effects associated with current ureteral stents, thus should cause less discomfort to patients.

Trans-urethral snare stent removal: a novel, self-constructed innovation for simultaneous ureteral stent removal and safety guidewire insertion

BACKGROUND

Ureteral stent insertion and subsequent removal remains one of the most common procedures performed in endourology. We aimed to evaluate a novel, one-step method, permitting simultaneous stent removal and guidewire passage using a self-constructed suture snare via standard cystoscopy. This method should be used prior to ureteroscopy, in cases of minimal stent encrustation and peri-ureteral mucosal oedema, where identification and subsequent cannulation of the ureteral orifice may be a challenge.

METHODS

A self-constructed suture snare is constructed using an open-ended ureteral catheter to facilitate this novel 'Switch' technique. Operative duration, cost feasibility and potential complications with this novel method were assessed in patients with an indwelling stent duration above 100 days.

RESULTS

Age inclusion in this study ranged from 21 to 35 years, with kidney, ureter and bladder scores below 6, in the five patients assessed. Previous ureteral stent indwelling time ranged from 106 to 315 days. Reasons for (pre-stented) ureteroscopy were mostly stone related. The overall recorded procedure time for the Switch technique was successfully performed in less than 96 s (range 68-95 s) in all cases within this series. No procedure-related complications were reported.

CONCLUSION

Utilizing the suture snare, the novel Switch technique was successfully performed in all cases assessed. This method is both time and cost feasible and could be easily utilized in resource-limited areas, regional centres or in cases where a stent grasper is not available, may have malfunctioned or cannot adequately approximate due to distal ureteral stent encrustation.

Success rate of repeat flexible ureteroscopy following previous failed access: An analysis of stent duration

INTRODUCTION

Approximately 8% of patients that undergo therapeutic or diagnostic ureteroscopy will have the procedure aborted and ureter stented due to failed access. The primary objective of this study was to assess mean stent duration prior to repeat ureteroscopy and to calculate the associated successful access rate.

METHODS

This retrospective, descriptive study evaluated all patients undergoing interval ureteroscopy following a failed procedure by endourologic surgeons at the University of Alberta from 2016-2018. Patients declining interval ureteroscopy, or those with malignant/known ureteral strictures were excluded from the study. The primary outcome measures were median time to salvage ureteroscopy and the rate of successful access of the repeat procedure.

RESULTS

A total of 119 patients were identified as having a failed ureteroscopy during our study period. First-time and recurrent stone formers accounted for 64 (53.8%) and 47 (39.5%) patients, respectively. Median stent duration to second procedure was 17 days (average 20, range 10-84). Most patients had their repeat ureteroscopy at 14 days or greater (81.5%); 22 (18.5%) patients had their repeat ureteroscopy between 10 and 13 days. The success rate of a second ureteroscopy after stenting was 99.2% (118/119).

CONCLUSIONS

Ureteric stenting following failed ureteroscopy leads to exceedingly high rates of successful access at interval procedure (99.2%). The standard duration of ureteric stenting employed at our institution is two weeks. Of the patients that underwent an accelerated second procedure (between 10-13 days of stenting), all had successful access at their interval procedure.

Changing the Status Quo: The 100 Most-Disruptive Papers in Urology?

OBJECTIVE

To identify key papers in urology using a novel bibliometric index called the disruption score.

METHODS

A PubMed search was conducted to identify papers published in Journal of Urology, European Urology, Urology, Urologic Oncology, Journal of Endourology, and BJU International, Nature Reviews Urology. Selected urology papers published in other medical journals were also included. Using a validated dataset of disruption scores for all papers published in 1954-2014, the top 100 most-disruptive urology papers, as well as the top 100 most-cited papers, were identified. Comparisons between both lists and across journals were investigated.

RESULTS

A total of 72,623 published articles were included. Journal of Urology had the most articles in the most-disruptive papers list (n = 69) followed by BJU International (n = 16). New England Journal of Medicine had the most papers in the most-cited papers list (n = 26) followed by Journal of Urology (n = 23). Only 7 papers were common to both the most-disruptive papers and most-cited papers lists. Oncology was highly represented among the most-cited papers (n = 60), whereas the most-disruptive papers included a broader representation of urology. The most common study design among the most disruptive papers was small case-series/case reports, whereas the most common study design among the most-cited papers was randomized controlled trials.

CONCLUSION

The disruption score identified landmark papers in urology that have introduced innovative ideas. Disruption score captures a unique profile of scientific impact that may be used in combination with other bibliometric indices to identify scholarly achievements in urology.

Huge encrusted ureteral stent forgotten for over 25 years: A case report

BACKGROUND

Ureteral stent insertion is a relatively non-invasive procedure commonly used in the field of urology to resolve urinary obstruction. However, they are sometimes forgotten and the risk of complications increases with time.

CASE SUMMARY

A 43-year-old woman with a history of recurrent urinary tract infections visited our hospital for evaluation of persistent left flank pain, and lower urinary tract symptoms despite anti-biotic treatment. She had received urological surgery in her teens but did not know the details of her surgery. Kidney, ureter, and bladder X-ray and abdominopelvic computed tomography revealed a forgotten left ureteral stent with huge encrustation at both ends and a severely dilated left kidney with parenchymal thinning. In order to remove the ureteral stent, a laparoscopic nephroureterectomy was planned. The ureteral stent was successfully removed, and she was discharged after recovery. The patient was followed up for two years after surgery and did not show any signs of long-term complications.

CONCLUSION

Long indwelling stents can cause dire complications requiring radical interventions. Stent registry systems, novel stent material development, and proper patient education is important for complication prevention.

The Efficacy and Safety of Ureteric Stent Removal with Strings versus No Strings: Which Is Better?

Objective

To evaluate the current evidence on the effectiveness and safety of ureteric stent removal using strings compared to conventional methods.

Materials and Methods

The electronic databases PubMed, Embase, China National Knowledge Infrastructure (CNKI), and the Cochrane Library were systematically searched up to March 2020. Two reviewers searched the literature, independently extracted the data, and evaluated the quality of the studies according to the inclusion and exclusion criteria. The data analysis was performed with the software program Review Manager 5.3.

Results

Eleven studies with a total of 1809 patients were included in the analysis based on the inclusion criteria. Our meta-analysis showed that visual analogue scale (VAS) scores were significantly lower in the string group than in the conventional group (weighted mean difference (WMD) -2.63; 95% confidence interval (CI) -3.68, -1.58; P < 0.00001). In terms of stent dwell time, the string group had an advantage (WMD -9.53; 95% CI -14.20, -4.86; P < 0.0001). In addition, no significant differences in the occurrence of urinary tract infection (UTI) (odds ratio (OR) 1.03; 95% CI 0.62, 1.72; P = 0.92), emergency room visits (OR 0.99; 95% CI 0.59, 1.67; P = 0.97), or other complications (P > 0.05) were observed between the two groups.

Conclusion

Our findings suggest that an extraction string is an effective and safe method for the removal of ureteric stents. This method gives patients the benefits of reduced pain and shortened stent dwell time without increasing the risk of UTI. Nevertheless, these findings should be further confirmed through large-volume, well-designed prospective randomized controlled trials (RCTs).

In vivo assessment of biodegradable magnesium alloy ureteral stents in a pig model

Today, ureteral stent technology is making progress towards the reduction of complications and patient discomfort. Therefore, magnesium alloys have become excellent candidate materials for manufacturing ureteral stents due to their biodegradability and antibacterial activity. Built on our previous work on biodegradable magnesium alloys, this article reports a semisolid rheo-formed magnesium implant that displays degradability and biocompatibility in vivo, and feasibility as ureteral stents in a pig model. Refined non-dendritic microstructure was observed in the rheo-formed alloy, whose grain size and shape factor were ca. 25.2 μm and ca. 1.56 respectively. Neither post-interventional inflammation nor pathological changes were observed in the urinary system during the implantation period of 14 weeks, and the degradation profile (14 weeks) meets the common requirement for the indwelling time of ureteral stents (8 to 16 weeks). Furthermore, histopathological observation and urinalysis results confirmed that the alloy had significantly higher antibacterial activity than the medical-grade stainless steel control. To our knowledge, this is the first in vivo study of biodegradable magnesium alloy as urinary implants in large animal models. Our results demonstrate that magnesium alloys may be a reasonable option for manufacturing biodegradable ureteral stents.

Advancing Toward 3D Printing of Bioresorbable Shape Memory Polymer Stents

Stents have evolved significantly since their introduction to the medical field in the early 1980s, becoming widely used in percutaneous coronary interventions and following nephrological procedures. However, the current commercially available stents do not degrade and remain in the body forever, leading to problems like restenosis in cardiovascular applications or requiring removal procedures in ureteral applications. Efforts to replace metal with resorbable materials have largely been halted after the commercial failure of and safety concerns elicited by Abbott's Absorb stent in 2017. Industry continues to use common polymers such as poly(l-lactide) (PLLA) and polycaprolactone (PCL) for biomedical products, but due to the weak mechanical properties of these bioresorbable materials in comparison to metals, these devices have struggled to accomplish the goals set, increasing risk of thrombosis. 3D printing stents using bioresorbable and shape memory materials could provide a method of patient-personalized production, remove the need for balloon expansion, and limit stent migration, thus bringing a new age of stent technology. The investigation of a range of 3D-printable and bioresorbable shape-memory polymers can provide solutions to the shortcomings of previously explored bioresorbable stents and revitalize the medical device industry efforts into advancing stent technology.

Surface analysis of ureteral stent before and after implantation in the bodies of child patients

The aim of this work was to determine which part of a double-J ureteral stent (DJ stents) showed the highest tendency to crystal, calculi, and biofilm deposition after ureterorenoscopic-lithotripsy procedure (URS-L) to treat calcium oxalate stones. Additionally, the mechanical strength and the stiffness of DJ stents were evaluated before and after exposure to urine. Obtained results indicated that the proximal (renal pelvis) and distal (urinary bladder) part is the most susceptible for post-URS-L fragments and urea salt deposition. Both, the outer and inner surfaces of the DJ ureteral stents were completely covered even after 7 days of implantation. Encrustation of DJ stents during a 31-day period results in reducing the Young’s modulus by 27–30%, which confirms the loss of DJ stent elasticity and increased probability of cracks or interruption. Performed analysis pointed to the need to use an antibacterial coating in the above-mentioned part of the ureteral stent to prolong its usage time and to prevent urinary tract infection.

Strategies to Improve Patient Outcomes and QOL: Current Complications of the Design and Placements of Ureteric Stents

Ureteric stents have played a vital role in relieving urinary obstruction in many urological conditions. Although they are extremely successful, stents have been associated with complications and reduced patients' health-related quality of life (HRQoL). There are many factors that may affect the quality and longevity of stents. In this review, we have highlighted the journey and innovation of ureteric stents through the modern day. A literature review was conducted to identify relevant articles over the last 20 years. There is a plethora of evidence with various indications for the use of ureteral stents and how they affect QoL. There is still ongoing research to develop the ideal stent with reduced encrustation, one that resists infection and is also comfortable for the patients. Stents made from metal alloys, polymers and biodegradable materials have unique properties in their own right but also have certain deficiencies. These have been discussed along with an overview of newly developed stents. Certain pharmacological adjuncts have also been highlighted that may be useful to improve patient's tolerance to stents. In summary, this paper describes the features of the different types of stents and the problems that are frequently encountered, including effect on patients' HRQoL and financial burden to healthcare providers.

Antibacterial Effects of Bimetallic Clusters Incorporated in Amorphous Carbon for Stent Application

The purpose of this work is the development of Ag/a:C and Ag-Au/a:C coatings for ureteral stents, to provide them with antimicrobial characteristics. Silver was selected because of its well-known antibacterial properties, while gold was included to assess its capacity to accelerate the silver ion release forming a galvanic couple between Au and Ag. Thus, the metallic (Ag) and bimetallic clusters (Ag-Au) were produced by three different configurations: (i) unbalanced magnetron sputtering (conventional sputtering), (ii) plasma gas condensation process, and by (iii) a combination between both previous approaches. Coatings with Ag-Au bimetallic clusters were characterized by transmission electron microscopy (TEM) in order to study the arrangement (alloy, core-shell, and galvanic couple) of these particles in the carbon matrix. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to quantify the Ag ions released through artificial urine from the different coatings deposited on thermoplastic polyurethane tape (one of the materials used in the manufacture of the ureteral stent ). Then, the antibacterial and cytotoxicity properties of Ag and Ag-Au/a:C coatings were evaluated. TEM shows that a biphasic structure was not detected, thus not allowing to anticipate the establishment of a galvanic couple. The ICP-OES results demonstrate that the silver ionization is mainly a function of the amount of silver incorporated in the amorphous carbon (a:C) matrix, and the formation of a bimetallic alloy has a detrimental effect on release of the silver ions. The antibacterial activity was regulated by the silver ionization mechanisms because the coatings with higher Ag release had a higher antibacterial activity.

Indwelling ureteric stents: Patterns of use and nomenclature

Objectives: To evaluate ureteric stenting practice patterns amongst a range of academic and community urologists, and to examine the nomenclature used to identify an indwelling ureteric stent from both our questionnaire and from a review of the literature.

Subjects and methods: A 16-question, peer-reviewed online survey was distributed to members of the Mid-Atlantic American Urological Association. Responses were collected over a 1-month period. Questions included demographics, ureteric stenting practice patterns, and utilization of stenting nomenclature. Inappropriate use of nomenclature was defined as a mismatch between the visually depicted stents and the written description amongst urologists. Trends in ureteric stenting and nomenclature usage were tabulated and analyzed.

Results: Of 863 members, 105 (12.2%) responded to the survey. There was a wide variety of practice settings, with the single-specialty group (44.2%) and academic/university (27.9%) being the two most common. Most providers used both cystoscopy and fluoroscopy to place stents (87.5%) as compared to fluoroscopy alone (12.5%). Most urologists (63.5%) removed stents with cystoscopy as compared to using a stent string (36.5%). While about half (51.0%) of the respondents left stents in situ for ≤3 months, many respondents (43.3%) felt comfortable with maximum dwell times of up to 6 months. The most commonly placed stent was the double pigtail stent (80.8%). However, most respondents inappropriately described this stent design as a Double J stent (72.1%). In the recent literature, 80% of articles clearly defined as using double pigtail stents, incorrectly identified their stent as a ‘Double J’.

Conclusions: Variations in ureteric stenting practice patterns exist amongst community and academic urologists. Although most urologists utilize double pigtail ureteric stents, the majority inaccurately identified this stent design as a Double J. We propose use of the term ‘indwelling ureteric stent’ (IUS) unless describing any specific stent design.

Surface-Treated Pellethanes: Comparative Quantification of Encrustation in Artificial Urine Solution

Introduction: Encrustation of implanted urinary tract devices is associated with significant morbidity. Pellethane^® is a polyether-based compound noted for its strength, porosity, and resistance to solvents. We assessed Pellethane thermoplastic polyurethane (TPU) with and without surface coatings 2-hydroxyethyl methacrylate (HEMA) and tetraethylene glycol dimethyl ether (TETRA) for the potential to resist encrustation in an artificial urine environment. Materials and Methods: Samples of Pellethane TPU, HEMA Pellethane TPU, TETRA Pellethane TPU, and hydrogel-coated ureteral stent (Cook^®) were suspended in a batch-flow model with an artificial urine solution (AUS). Every 48 hours for 90 days, 40% of the solution was replaced with fresh AUS. All samples were stored in a 37°C incubator. Subsequently, the samples were thoroughly dried for 48 hours before weighing. Scanning electron microscopy was used to assess the degree of encrustation. Nu-Attom Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to determine the precise compositions of the encrustation specifically with regard to calcium, magnesium, and phosphate. Results: At the conclusion of the 90-day trial, the samples were analyzed, and the average mass changes were as follows: stent 63.78%, uncoated Pellethane TPU 11.50%, HEMA-coated Pellethane TPU 2.90%, and TETRA-coated Pellethane TPU 0.60%. Pellethane TPU products, and specifically those coated with HEMA and TETRA, exhibited less average mass increase and a lesser propensity to form encrustation than the traditional urinary tract stent. The mass increases noted on coated Pellethane devices were primarily ionic, whereas that of the stent was not. Conclusion: Pellethane, particularly with an HEMA-based preventative coating, may serve as a favorable alternative to traditional urinary stent material, providing its improved resistance to encrustation.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.