Ureteral stents in urolithiasis

Surface Modification of Zn-Cu Alloy with Heparin Nanoparticles for Urinary Implant Applications

In this work, an investigation on the Zn-Cu alloy coated with heparin was conducted in order to explore the potentiality of its application as a feasible alternative for biodegradable implants, with the specific goal of addressing the issue of encrustation in the urinary system. The stability of the nanoparticles were characterized by dynamic light scattering. Typical surface characterization such as X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were used to demonstrate a successful immobilization of the NPs. The in vitro corrosion behavior was studied by potentiodynamic polarization and immersion tests in artificial urine (AU) at 37 °C. The 8 weeks in vivo degradation, encrustation resistance, hemocompatibility, and histocompatibility were investigated by means of implantation into the bladders of rats. Both in vitro and in vivo degradation tests exhibited a higher degradation rate for Zn-Cu and NPs groups when compared to pure Zn. Histological evaluations and hemocompatibility revealed that there was no tissue damage or pathological alterations caused by the degradation process. Furthermore, antiencrustation performance and urinalysis results confirmed that the modified alloy demonstrated significant encrustation inhibitory properties and bactericidal activity compared to the pure Zn control. Our findings highlight the potential of this modified alloy as an antiencrustation biodegradable ureteral stent.

The effect of ureteral double J stent insertion on work performance in patients undergoing endoscopic stone treatment

Introduction

Despite the developments in the material of the double J (DJ) stents and the production of thinner ones of desired sizes, patients continue to experience troublesome DJ stent-related symptoms in their lives. This study aimed to determine how DJ stenting affects patients' work performance after endoscopic stone surgery.

Material and methods

A total of 107 patients underwent placement of a ureteral stent after ureterorenoscopy (URS)/retrograde intrarenal surgery (RIRS), and only active and full-time working patients were included. All patients were asked to complete the validated Turkish version of the work performance score (WPS) questionnaire in the Ureteral Stent Symptom Questionnaire (USSQ) the day before stent removal and again one month after stent removal.

Results

Of the participants, 32.7% (n = 35) were female and 67.3% (n = 72) were male; the mean age was 41 (19-80) years. The workday loss had no statistically significant correlation with patient BMI, stone size, or stent indwelling time (p >0.005); however, a statistically significant negative correlation was detected with patient age (r = -0.335, p <0.001). The medians of WPSs with the stent and without the stent were 6 (3-15) and 3 (3-12), respectively (p <0.001).

Conclusions

Although DJ catheterization is a crucial tool for urological practice, it may increase the social and economic burden of patients due to reduced work performance and lost workdays. Therefore, limiting the duration of the DJ stent's stay and providing treatments to minimize patient symptoms will positively impact their professional lives. It would be beneficial to avoid DJ stenting in routine practice unless medically necessary.

The Impact of the Double J Stent on Health and Sexual Life

Double J stents are commonplace tools used in modern urology, serving as a vital aid in the drainage of the upper urinary system. Along with the numerous advantages of these catheters, numerous negative consequences have also been addressed throughout time. Among the most common symptoms associated with ureteral catheters are those associated with LUTS (lower urinary tract symptoms), such as dysuria, urinary urgency, pollakiuria, the feeling of incomplete emptying of the bladder, urinary incontinence, or even urinary tract infections (UTIs). Complications associated with sexual dysfunction, including dyspareunia and pain during sex, which can lead to erectile dysfunction or loss of orgasm, are less discussed in the literature. This small review tries to focus on the most important aspects of low urinary symptoms that affect the general quality of life and those related to the quality of sexual life, which are less discussed but of particular importance in the lifestyle of any patient with such ureteral device.

Recanalize ureteral stents with focused ultrasound

BACKGROUND

Maintaining ureteral patency is imperative to preventing renal injury and systemic infection. Ureteral stents are small conduits connecting the kidney and the bladder. They have been widely used to treat ureteral obstructions and ureteral leaks. The most problematic and frequent stent-associated complication is stent encrustation. This occurs when mineral crystals (e.g. calcium, oxalate, phosphorus, struvite) are deposited onto the surface and internal lumen of the stent. Encrustation can lead to the obstruction of a stent and increases risk of systemic infection. As a result, ureteral stents need to be replaced typically every 2-3 months.

PURPOSE

In this study, we present a non-invasive, high-intensity focused ultrasound (HIFU)-based technique to recanalize obstructed stents. By taking advantage of the mechanical force produced by a HIFU beam, including acoustic radiation force, acoustic streaming, and cavitation, HIFU can break up encrustations, clearing the stent of obstruction.

METHODS

The ureteral stents for this study were obtained from patients undergoing ureteral stent removal. Under the guidance of ultrasound imaging, the encrustation in the stents were located, and then targeted by HIFU at frequencies of 0.25 and 1 MHz. The duty cycle of HIFU was 10%, and the HIFU burst repetition rate was 1 Hz, while the HIFU amplitude was varied to find the threshold pressure that would displace encrustations. The treatment duration was limited at 2 min (or 120 shots from HIFU). The treatments were carried out in two different orientations (parallel and perpendicular) of the ureteral stent with respect to the HIFU beam. For each setting, five treatments were conducted for a maximum duration of 2 min. During the entire treatment, an ultrasound imaging system was used to monitor the movement of encrustations inside the stent. The peak negative HIFU pressures needed to move the encrustations inside the stent was recorded for quantitative analysis.

RESULTS

Our results demonstrated that at both 0.25 and 1 MHz ultrasound frequencies, obstructed stents could be recanalized. At 0.25 MHz, the needed average peak negative pressure was 0.52 MPa in parallel orientation and 0.42 MPa in perpendicular orientation. At 1 MHz, the needed average peak negative pressure was 1.10 MPa in parallel orientation and 1.15 MPa in perpendicular orientation CONCLUSIONS: This first in-vitro study has demonstrated the feasibility of non-invasive HIFU to recanalize ureteral stents. This technology has a potential to reduce the need for ureteral stent exchange.

Bladder stone formation due to neglected double J stent: a case report

Introduction and importance

Double J (DJ) stents are commonly used in genitourinary procedures, but they can lead to complications including infection, hematuria, encrustation, and stone formation. The longer the duration of encrustation, the greater the risk of complications and renal dysfunction. Forgotten stents pose challenges for patients and can require endourological or open surgical procedures.

Case presentation

A 40-year-old man with hypertension and coronary artery disease had a forgotten DJ stent for 3 years, causing suprapubic pain and dysuria. Kidney, ureter, and bladder (KUB) revealed a coiled DJ stent with a large bladder stone and encrustation, and an open cystolithotomy was successfully performed. Recovery was uneventful, and the patient was discharged without complication.

Clinical discussion

Ureteral stents, including the DJ stent, are commonly used for urological conditions but can cause complications if retained beyond the intended timeframe. Optimal timing for stent removal is crucial, and patients' healthcare knowledge and adherence are critical to preventing retention. KUB X-ray can evaluate stent encrustation and bladder stones. Cystoscopy is the typical approach for stent removal, but supplementary interventions may be necessary. Open surgery was recommended for removing a large bladder stone and encrusted stent in this case.

Conclusion

Timely removal of DJ stents is crucial to avoid complications. Extended retention can cause problems such as encrustation and stone formation. Patient education and adherence are essential to prevent retention and forgetfulness. This case report highlights the importance of careful management of patients with DJ stents for optimal outcomes and prevention of complications.

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.

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.

Retained Ureteral Stent Encrustation After Stent Removal: A Case Report

Ureteral stents are used to relieve acute or chronic urinary tract obstructions and may be complicated by stent encrustation. The development of encrustation is related to indwelling time, stent composition, bacterial biofilm formation, malabsorptive disorders, metabolic disorders (hypercalcemia, hyperuricosuria, pH imbalance), and cancer. Without intervention, encrustation may lead to luminal obstruction, infection, stent fracture, or ureteral avulsion during removal. Rarely, forced removal of an encrusted stent may cause the encrustation to remain in the urinary tract which can lead to further complications. Diagnosis of a retained encrustation includes evaluation with X-ray, ultrasound, and CT. Management strategies of retained encrustations are not standardized but may include removal with flexible ureteroscopy. In the following case, we present a 58-year-old male with retained encrustation material following non-forced stent removal that was not readily observed on initial imaging. CT demonstrated a curved, tubular radiodensity representing calcified encrustation material, and the diagnosis of retained encrustation was confirmed after successful removal with flexible ureteroscopy. We concluded that ureteral stent encrustation can remain in the urinary collecting system following stent removal, although this complication is rare and not well studied.

REVIEW ON COMPLICATIONS AND ADVERSE EFFECTS OF METALLIC URINARY STENTS

Urinary stents, be it urethral or ureteral, polymeric, metallic or biodegradable, are one of the most frequently used tools in urology and they have been used for decades in prophylactic and therapeutic setting. Although relatively low invasive, they are prone to complications and adverse effects so much that complication rates up to 100% have been described. Many reviews have focused either on specific groups of patients or particular stent types, materials or designs but so far, no comprehensive review on complications has been published. To tackle this issue, a working group was set up within ENIUS (European Network of multidisciplinary research to Improve Urinary Stents) tasked with literature search in order to screen for and systematically review published stent complications in urethra (male only) and ureters (polymeric and metallic ureteral stents in both sexes) when used in obstructed systems. In this paper, we review, catalogue and summarize complications published for metallic urethral and ureteral stents.

Management of encrusted ureteral stents: Two center experience

Introduction: We present our experience of the endourological management of encrusted ureteral stents (EUS) and a literature review on forgotten encrusted ureteral stents. Methods: A total of 13 encrusted ureteral stents from 12 patients were removed in two hospitals. The medical records were retrospectively analyzed for stent indication, indwelling time, clinical presentation, investigations, type and the number of surgical procedures, operative time, complications, duration of hospital stay, and the follow-up. Results: Five ureteral stents (US) inserted before ESWL(extracorporeal shockwave lithotripsy) for renal stones, seven US for ureteric stones with ureteric colic, and one ureteral stent for post ureteroscopy procedure. The mean indwelling time was 15.07 ± 7.34 months with a range from 6 to 24 months. The mean Kidney,Ureter and Bladder (KUB) score of encrusta-tion grading was 11.84 ± 2.07 with a range from 9 to 15. The encrusted stents were removed by a combination of cystolithotripsy, semi-rigid ureteroscopy (URS), retrograde intrarenal surgery (RIRS), percutaneous nephrolithotomy(PCNL), and ESWL. The average total number of procedures to remove one EUS was 3 ± 1.08 with a range of 2 to 5 proce-dures. Six encrusted stents were removed in one, five stents required two, one stent required three and one stent required four hospital admissions. The median operative time was 210 minutes with a range of 60 to 660 minutes per EUS removal and the mean hospital stay was 2.69 ± 1.43 days with a range of 1 to 6 days. All patients had successful removal of encrusted stent and complete stone clearance with no major complica-tions. In the follow-up, one patient had recurrent ureteric stone, one patient on regular stent exchange due to poor renal function and one patient developed significant ureteric stricture referred for reconstruction. Conclusions: Removal of forgotten encrusted impacted ureteral stents is challenging and requires a multimodal surgical approach. It adds significant costs to the health care system and in addition it affects patient safety and quality of life. Patient education, avoiding unnecessary ureteral stent place-ment and a computerized stent monitoring system reduces the incidence of forgotten ureteral stents and their complications.

A Novel Endoscopic Approach for Distally Calcified Ureteral Stents

Double-J ureteral stents are an invaluable tool in urology and are one of the most widely used stents in the world. However, when left in situ for prolonged periods, so-called “retained” ureteral stents can lead to numerous complications such as migration, hematuria, encrustation, or stent occlusion. These complications present severe challenges in urologic management. Notably, encrustation of ureteral stents may increase the risk of renal impairment and other potentially life-threatening complications. Here, we present the case of a 34-year-old female with a left double-J ureteral stent who presented to the Emergency Department (ED) with a one-day history of left flank pain and febrile urinary tract infection. 

Effect of phytate on crystallization on ureteral stents and bacterial attachment: an in vitro study

The use of double J ureteral stents can lead to several adverse effects, as urinary infection. Bacteria tend to colonize the stent surface, leading to the formation of bacterial biofilms. The presence of urease-producing bacteria increase the urine pH leading to the incrustation and blockage of the stent. On the other hand, these large crystalline masses function as niduses, allowing the attachment of even more bacteria and decreasing its exposure to antibiotics. The aim of this in vitro study was to assess the effect of phytate on the attachment of bacteria to the catheter surface under conditions that favor crystallization. Catheter sections were incubated in a synthetic urine medium (pH 6.5) in the presence or absence of Pseudomonas aeruginosa and phytate. Amount of calcium deposits was measured using an Arsenazo III colorimetric method and the number of attached bacteria to the stent was determined. Differences were assessed using an ANOVA with a Bonferroni post hoc test. The formation of calcium phosphate deposits (brushite and hydroxyapatite) and oxalate crystals (COM), as were as the amount of bacteria decreased when phytate was present. Thus, phytate successfully decreased bacterial adhesion by inhibiting the formation of crystalline deposits.

The accumulation of particles in ureteric stents is mediated by flow dynamics: Full-scale computational and experimental modeling of the occluded and unoccluded ureter

Ureteric stents are clinically deployed to restore urinary drainage in the presence of ureteric occlusions. They consist of a hollow tube with multiple side-holes that enhance urinary drainage. The stent surface is often subject to encrustation (induced by crystals-forming bacteria such as Proteus mirabilis) or particle accumulation, which may compromise stent's drainage performance. Limited research has, however, been conducted to evaluate the relationship between flow dynamics and accumulation of crystals in stents. Here, we employed a full-scale architecture of the urinary system to computationally investigate the flow performance of a ureteric stent and experimentally determine the level of particle accumulation over the stent surface. Particular attention was given to side-holes, as they play a pivotal role in enhancing urinary drainage. Results demonstrated that there exists an inverse correlation between wall shear stress (WSS) and crystal accumulation at side-holes. Specifically, side-holes with greater WSS levels were those characterized by inter-compartmental fluid exchange between the stent and ureter. These "active" side-holes were located either nearby ureteric obstructions or at regions characterized by a physiological constriction of the ureter. Results also revealed that the majority of side-holes (>60%) suffer from low WSS levels and are, thus, prone to crystals accumulation. Moreover, side-holes located toward the proximal region of the ureter presented lower WSS levels compared to more distal ones, thus suffering from greater particle accumulation. Overall, findings corroborate the role of WSS in modulating the localization and extent of particle accumulation in ureteric stents.

Urethral beading: A unique radiographic finding following laser lithotripsy for ureteric stent encrustation

We present an interesting case of ureteric stent encrustation in a 35-year-old male who was lost to follow up for 8 months during the Covid-19 pandemic. After clearing severe stent encrustation with ureteroscopy and laser lithotripsy, the patient presented with urinary retention and multiple failed catheterizations. They were found to have numerous calcified urethral fragments secondary to stent encrustation, with a unique radiographic appearance of a string of beads overlying the pubic symphysis. A new stent was inserted and the patient was lost to follow up for a further 4 months, during which time pronounced encrustation formed again.

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.

New Stent Technologies

Ureteral stents are an indispensable part of any (endo-) urologic practice. Despite the widely demonstrated advantages of stents, they also carry a considerable risk of side effects and complications, such as urinary symptoms, pain, hematuria, decreased quality of life, stent-related infection, and encrustation. Multiple pathways in preventing or mitigating these side effects and complications and improving stent efficacy have been and are being investigated, including stent architecture and design, biomaterials, and coatings. This article provides an update on currently researched and available stents as well as future perspectives.

Validation of robotic-assisted ureteroplasty with buccal mucosa graft for stricture at the proximal and middle ureters: the first comparative study

Although ureteroplasty with buccal mucosa graft for long-segmental ureteral stenosis has been developed long ago, evidence was still restricted to case series in published literature. This study aims to validate ureteroplasty with buccal mucosa graft (BMG) in long-segment stricture at the proximal and middle ureters under designed comparative methods. From April 2015 to January 2019, we performed robotic-assisted ureteroplasty with BMG with a two-phase design and compared ureteroplasty and BMG (phase 2 surgery) with endoscopic stenting (phase 1 surgery). Paired data of effective renal plasma flow (ERPF), glomerular filtration rate (GFR), hydronephrosis grade, and physical and psychological domains of the World Health Organization Quality of Life (WHOQOL)-BREF were compared. A total of 29 patients were enrolled, and only three (10%) patients had hydronephrosis resolution after treatment with endoscopic stenting (p = 0.250 to baseline). Compared to endoscopic ureteral stent, Hedges' g of ureteroplasty with BMG was 0.56 (95% CI 0.43-0.69), 0.63 (95% CI 0.46-0.80), 0.80 (95% CI 0.56-1.04), and 1.06 (95% CI 0.69-1.43) in EGFR, GFR, physical domain of WHOQOL-BREF, and psychological domain of WHOQOL-BREF, respectively (All significance; p < 0.001). After 12-month follow-ups, no recurrence of stricture was reported. In conclusion, Robotic-assisted ureteroplasty with BMG onlay is efficient in reconstruction of long-segment stricture of the proximal and middle ureters.

The effect of perirenal fat stranding on infectious complications after ureterorenoscopy in patients with ureteral calculi

Objective

Perirenal fat stranding (PFS) is linear areas of soft-tissue attenuation in the perirenal space on non-contrast computed tomography. The present study aimed to investigate whether PFS is associated with infectious complications after ureterorenoscopy (URS) in patients with ureteral calculi in any location.

Methods

The data of 602 patients with ureteral stones who underwent URS were analyzed retrospectively. The patients were divided into two groups as Group 1 (PFS not detected) and Group 2 (PFS detected). Gender, and age of patients, size, side, and location of the stone, operation time, double-J stent insertion status, perioperative ureter injury, postoperative infection after URS and related complications, and duration of hospital stay were compared.

Results

While PFS was not detected in 530 patients, PFS was detected in 72 patients. The mean age, male/female ratio, side and localization of the stones, operation time, and perioperative insertion of the double-J after lithotripsy were statistically similar (p>0.05). The median stone diameter was smaller in Group 2 (9 mm vs. 8 mm) (p=0.033). Fever was observed in 30 and 38 patients in Group 1 and Group 2, respectively (p=0.0001). Urinary tract infection was detected in 24 and 27 patients in Group 1 and Group 2, respectively (p=0.0001). The urosepsis did not occur in any patients in Group 1, whereas 8 (11.1%) patients in Group 2 experienced urosepsis (p=0.0001).

Conclusion

According to the results of the present study, patients with ureteral stones accompanied by PFS are much more prone to ureteral injuries and infectious complications such as urinary tract infection, fever, and sepsis after URS.

Neglected double-J stent with giant bladder stone: a case report

Double-J (DJ) stents have been widely utilized in urological practice. They are commonly used to relieve ureteral obstruction. Serious complications may occur when stents are left in place for long periods of time. In the present paper, we report a patient with a neglected DJ stent that had been inserted for five years after uterus-tumor surgery and led to a bladder stone. We report a case of a female who presented a bladder stone with a right DJ stent in the pelvic cavity. The stone was evident in radiological examination in an incidental finding. The treatment was transurethral cystolithotripsy. This case reminds us of the necessity of providing enough information and appropriate knowledge pertaining to the insertion of a ureteral stent. Transurethral cystolithotripsy is one of the treatment methods and can be suggested as a definitive method in consideration that it is a clinically effective and safe intervention.

Anomalous Circumrenal Inferior Vena Cava Associated With Horseshoe Kidney

A 69-year-old male presented with periumbilical pain radiating across his abdomen, with associated nausea and emesis. CT imaging of his abdomen and pelvis revealed calculi in the right and left ureterovesical junctions with hydroureteronephrosis bilaterally. Furthermore, the imaging revealed that the patient had a horseshoe kidney with an associated anomalous inferior vena cava (IVC) that split superiorly to the horseshoe kidney at the L1 level and rejoined inferior to the horseshoe kidney at the L5 level. The IVC took on a "circumrenal" course, as it traversed the right kidney with an anterior and posterior portion. Furthermore, the patient's right ureter was compressed between the anterior portion of the IVC and the right kidney. We hypothesize that the development of the horseshoe kidney around the 7 to 8th week of gestation created a path of resistance for the forming of IVC around the same time. While surgical correction is not warranted, recognition of this circumrenal IVC variant could have major implications for planning of procedures, such as IVC filter placement.

In vivo urinary compatibility of Mg-Sr-Ag alloy in swine model

A biodegradable metallic ureteral stent with suitable mechanical properties and antibacterial activity remains a challenge. Here we reveal the scientific significance of a biodegradable Mg-Sr-Ag alloy with a favorable combination of balanced mechanical properties, adjustable indwelling time in urinary tract and evident antibacterial activity via in vivo experiments in a swine model. Attributed to the rheo-solidification process, equiaxial microstructure and significantly refined grains (average grain size: 27.1 μm) were achieved. Mg₁₇Sr₂ and Mg₄Ag were found as the primary precipitates in the matrix, due to which the alloy obtained ca. 111% increase in ultimate tensile strength in comparison to pure magnesium. Both the in vitro and in vivo results demonstrated the satisfactory biocompatibility of the alloy. Histological evaluation and bioindicators analysis suggested that there was no tissue damage, inflammation and lesions in the urinary system caused by the degradation process. The stent also improved the post-operative bladder functions viewed from the urodynamic results. Our findings highlight the potential of this alloy as antibacterial biodegradable urinary implant material.

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Innovative biodegradable antibacterial Mg-Sr-Ag alloy.

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In vivo study in pig ureter models.

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Enhanced mechanical properties and adjustable indwelling time.

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Outstanding urinary compatibility and evident antibacterial activity.

The efficacy and safety of mirabegron in treating ureteral stent-related symptoms: A systematic review and meta-analysis

OBJECTIVES

This meta-analysis aimed to assess the efficacy and safety of mirabegron in treating ureteral stent-related symptoms.

METHODS

MEDLINE, EMBASE, and the Cochrane Controlled Trials Register were searched to identify randomized controlled trials (RCT) of mirabegron in treating ureteral stent-related symptoms. We conducted a systematic review and meta-analysis based on the eligible RCT.

RESULTS

Five RCT including 546 patients and comparing mirabegron with placebo or blank control were involved in the present research. Regarding efficacy, mirabegron was superior to controls in urinary symptom score (P = .0006) and general health score (P < .0001) of the Ureteral Stent Symptom Questionnaire, total International Prostate Symptom Score (P < .00001), quality of life (P < .0001), analgesic use (P = .008), and readmission or visit to hospital due to discomfort (P = .001). Safety assessments including adverse events (P = .40) suggested that mirabegron was well tolerated.

CONCLUSIONS

The present meta-analysis shows that mirabegron is an effective and safe treatment for relieving ureteral stent-related symptoms with a low occurrence of adverse events.

Assessment of encrustation and physicochemical properties of poly(lactide-glycolide) - Papaverine hydrochloride coating on ureteral double-J stents after long-term flow of artificial urine

Implantation of ureteral stents is associated with inconvenience for the patient, which is related to the natural ability of the ureter to contract. The most frequently used solution is the systemic administration of a diastolic drug, which has a relaxing effect on smooth muscle cells and decreases inconvenience. Current interdisciplinary research aimed at reducing the complications after the implantation of ureteral stents used in the treatment of upper urinary tracts with regard to infection, initiation of encrustation, and fragmentation of stents, and patient pain has not been resolved. This study presents the results of research regarding the impact of a biodegradable coating with the active substance on the physical and chemical properties of ureteral stents used in the treatment of the upper urinary tract. The surface of polyurethane double-J stents was coated with poly(lactide-glycolide) (PLGA) 85/15 loaded with papaverine hydrochloride (PAP) with diastolic properties. The coating for ureteral stents has been designed for short-term implantation. The effect of the coating on the process of encrustation and PAP release by the dynamic in vitro model with artificial urine (AU) up to 30 days was evaluated. The influence of AU on the physical and chemical properties of ureteral stents was determined. As part of the study, surface structure and topography researches; chemical composition analyses using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and wetting; and surface roughness studies of both PUR stents and coated stents were carried out. The proposed biodegradable PLGA+PAP coating is characterized by controlled drug release, while optimal physicochemical properties does not increase the encrustation process.

Impact of differential ureteral stent diameters on clinical outcomes after ureteroscopy intracorporeal lithotripsy: A systematic review and meta-analysis

In this meta-analysis we assessed whether the diameter of ureteral stents (4.7-5-Fr, 6-Fr) has an impact on the rate of occurrence of urinary tract symptoms and complications after successful URS and intracorporeal lithotripsy. A systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. A rigorous search for relevant studies published in MEDLINE, Embase, and the Cochrane Controlled Trials Register was conducted to find informative randomized controlled trials. The reference lists of relevant articles were also manually searched and reviewed. The protocol was prospectively registered at PROSPERO (CRD42020202164). All statistical evaluations were performed using RevMan software version 5.3.0. Seven articles comprising 547 patients were included in the meta-analysis. After placement of ureteral stents with different diameters for approximately 1 week, we found that ureteral stents with smaller diameters (4.7-5-Fr) were associated with significant improvements in the main domain scores on the Ureteral Stent Symptom Questionnaire, such as urinary symptoms (mean difference -4.47, 95% confidence interval -5.87 to -3.08; P < 0.00001) and body pain (mean difference -2.48, 95% confidence interval -4.37 to -0.59; P = 0.01), but poor outcomes in stent migration compared to ureteral stents with a 6-Fr diameter (odds ratio 3.00, 95% confidence interval 1.06-8.51; P = 0.04). However, there were no significant differences in Ureteral Stent Symptom Questionnaire scores with regard to work performance (mean difference -0.56, 95% confidence interval -2.52 to 1.40; P = 0.58), general health (mean difference -2.29, 95% confidence interval -4.95 to 0.37; P = 0.09), additional problems (mean difference -0.43, 95% confidence interval -1.02 to 0.15; P = 0.15), and complications such as fever (odds ratio 0.75, 95% confidence interval 0.24-2.39; P = 0.63). Ureteral stents with a diameter of 4.7-5-Fr have better outcomes than those with a diameter of 6-Fr, based on the Ureteral Stent Symptom Questionnaire pain and urinary tract symptoms scores. However, they are more prone to migration compared to those with a larger diameter.

Application of Omaha system-based continuing care in patients with retained double J tube after urinary calculus surgery

OBJECTIVE

To explore the effect of Omaha system-based continuing care in patients with retained double J tube after urinary calculus surgery.

METHODS

A total of 124 patients hospitalized with retained double J ureteral stent after urinary calculus surgery were selected as the research subjects. According to the random number table method, they were divided into observation group (n=62) and control group (n=62). The control group was given regular continuing care, while the observation group was given the Omaha system-based continuing care. Awareness of knowledge regarding retained double J tube, anxiety, depression, sleep quality, quality of life, incidence of complications, and patient satisfaction were compared between the two groups.

RESULTS

Compared with the control group, patients in observation group did better in the knowledge awareness concerning the purpose of retained double J ureteral stent, daily water consumption, exercise, urination, and extubation time; the observation group was also significantly higher in Self-Rating Anxiety Scale (SAS) scores and lower in Self-Rating Depression Scale (SDS) scores and PSQI scores (all P<0.05). The quality of life (QOL) scores in all aspects of patients in observation group were significantly higher than those of the control group (P<0.05). The incidence of infection, bleeding, fever, back pain, displacement, bladder irritation or other complications in the observation group was significantly lower than that of the control group. Satisfaction rate of patients in the observation group with out-of-hospital continuing care was significantly higher than that of patients in the control group (all P<0.05).

CONCLUSION

The Omaha system-based continuing care has a better nursing effect on patients with retained double J tube after urinary calculus surgery. It can improve patients' compliance with treatment, relieve their anxiety and depression, improve their quality of life, reduce overall complications incidence rate and ultimately improve patients' satisfaction with clinical care.

Effects of mirabegron on JJ stent-related symptoms: A multicentric study

AIMS OF THE STUDY

To investigate the effect of mirabegron 50 mg/daily for JJ stent-related symptoms after ureteroscopic stone surgery.

METHODS

Medical records of 145 patients who were given a single daily oral dose of 50 mg of mirabegron for relieving stent-related symptoms were retrospectively analysed. Demographic and clinical data and stone parameters were recorded. All participants completed the Turkish version of the Ureter Symptom Score Questionnaire (USSQ-T) on the postoperative 7th day, and again after at least 3 weeks, before JJ stent removal. The severity of stent-related symptoms was statistically compared before and after the mirabegron treatment.

RESULTS

The mean urinary symptoms score decreased significantly from 30.87 ± 9.43 to 22.61 ± 6.78 (P < .0001), mean body pain score decreased significantly from 21.82 ± 11.22 to 14.03 ± 7.52 (P < .0001), mean work performance score decreased from 10.50 ± 8.61 to 7.02 ± 6.51 (P < .0001) and mean general health score decreased significantly from 15.43 ± 6.50 to 11.12 ± 3.70 (P < .0001). The mean sexual matters score significantly decreased from 3.88 ± 3.40 to 2.48 ± 2.03 (P < .0001), the additional problem score decreased from 9.31 ± 4.61 to 6.51 ± 2.83 (P < .0001) and the overall quality of life (QoL) score decreased from 5.18 ± 1.94 to 4.23 ± 1.71 after mirabegron use (P < .0001).

CONCLUSION

Daily use of 50 g of mirabegron significantly improved stent-related symptoms, sexual matters and quality of life.

Association between ureteric stent dwell time and urinary tract infection

BACKGROUND

Ureteric stone obstruction commonly presents to the emergency department, with definitive management often involving ureteroscopy and laser lithotripsy. Insertion of a ureteric stent prior to staged lithotripsy is commonly performed in the public healthcare system. Foreign bodies in the urinary tract are also known to increase urinary tract infection (UTI) risk. This study aims to evaluate the association between stent dwell time and UTI prior to lithotripsy.

METHODS

The medical records of all patients who were treated for ureteric stones with initial stent insertion and staged lithotripsy, from 1 January 2018 to 30 June 2019 at a single tertiary centre, by eight urologists were retrospectively reviewed. Demographic features, disease factors and urine culture data were collected and analysed.

RESULTS

Of the 172 patients (median age 56.7 years) identified, one-third had a positive pre-stent urine culture. Twenty-three percent had a positive pre-lithotripsy urine culture with 38% of females compared with 15% of males having a positive culture (P = 0.001). Only 4.3% of patients had a pre-lithotripsy UTI when the stent dwell time was less than 1 month compared with 26.2% when ureteric stents were in situ for longer than 1 month (P = 0.021). The correlation between ureteric stent dwell time and pre-lithotripsy UTI was not linear. Patient comorbidities, stone size, burden and location were not statistically correlated to pre-lithotripsy UTI.

CONCLUSION

In delayed two-staged surgical management of acute urolithiasis, optimal ureteric stent dwell time is less than 1 month to reduce pre-lithotripsy UTI. Female gender is an independent risk factor for pre-lithotripsy UTI.

A prospective randomized study to define the role of low dose continuous prophylactic antibiotics and anti-adherence agents in altering the microbial colonization related to indwelling double-J stents

Objective

Despite conflicting evidence, it is common practice to use continuous antibiotic prophylaxis (CAP) in patients with indwelling double-J (DJ) stents. Cranberry extracts and d-mannose have been shown to prevent colonization of the urinary tract. We evaluated their role in this setting.

Methods

We conducted a prospective randomized study to evaluate patients with indwelling DJ stents following urological procedures. They were randomized into three groups. Group A (n=46) received CAP (nitrofurantoin 100 mg once daily [OD]). Group B (n=48) received cranberry extract 300 mg and d-mannose 600 mg twice daily (BD). Group C (n=40) received no prophylaxis. The stents were removed between 15 days and 45 days after surgery. Three groups were compared in terms of colonization of stent and urine, stent related symptoms and febrile urinary tract infections (UTIs) during the period of indwelling stent and until 1 week after removal.

Results

In Group A, 9 (19.5%) patients had significant bacterial growth on the stents. This was 8 (16.7%) in the Group B and 5 (12.5%) in Group C (p-value: 0.743). However, the culture positivity rate of urine specimens showed a significant difference (p-value: 0.023) with Group B showing least colonization of urine compared to groups A and C. There was no statistically significant difference in the frequency of stent related symptoms (p-value: 0.242) or febrile UTIs (p-value: 0.399) among the groups.

Conclusion

Prophylactic agents have no role in altering bacterial growth on temporary indwelling DJ stent, stent related symptoms or febrile UTIs. Cranberry extract may reduce the colonization of urinary tract, but its clinical significance needs further evaluation.

Anesthetic management using a combination of anterior quadratus lumborum block and erector spinae plane block for robot-assisted partial nephrectomy: two case reports

BACKGROUND

There has been increasing attention regarding quadratus lumborum block (QLB) and erector spinae plane block (ESPB) as effective truncal blocks. There have been reports of combined QLB and ESPB usage in hip surgery resulting in a symbiotic increase in effectiveness. However, there have been no reports regarding robot-assisted partial nephrectomy (RAPN), which requires multiple port holes ranging from near the xiphoid process to below the umbilicus. We hypothesized that the combined use of QLB and ESPB was an option for anesthesia and analgesia during RAPN.

CASE PRESENTATION

Anterior QLB and ESPB were applied to two patients undergoing scheduled RAPN. With intravenous patient-controlled analgesia, the post-surgery numerical rating scale scores were < 3/10 at rest and < 5/10 upon movement, throughout the perioperative time.

CONCLUSIONS

The combination of QLB and ESPB could be an option for the postoperative analgesia in RAPN.

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

BACKGROUND

Encrustation of ureteral double J stents is a common complication that may affect its removal. The aim of the proposed study is to evaluate the efficacy and safety of a new oral composition to prevent double J stent encrustation in indwelling times up to 8 weeks.

METHODS

A double-blinded, multicenter, placebo-controlled trial was conducted with 105 patients with indwelling double J stents enrolled across 9 public hospitals in Spain. The patients were randomly assigned (1:1) into intervention (53 patients) or placebo (52 patients) groups for 3 to 8 weeks and both groups self-monitored daily their morning urine pH levels. The primary outcome of analysis was the degree of stent ends encrustation, defined by a 4-point score (0 - none; 3 - global encrustation) using macroscopic and electron microscopy analysis of crystals, after 3 to 8-w indwelling period. Score was exponentially transformed according to calcium levels. Secondary endpoints included urine pH decrease, stent removal, and incidence of adverse events.

RESULTS

The intervention group benefits from a lower global encrustation rate of stent ends than placebo group (1% vs 8.2%; p < 0.018). Mean encrustation score was 85.12 (274.5) in the placebo group and 18.91 (102.27) in the intervention group (p < 0.025). Considering the secondary end points, treated patients reported greater urine pH decreases (p = 0.002). No differences in the incidence of adverse events were identified between the groups.

CONCLUSIONS

Our data suggest that the use of this new oral composition is beneficial in the context of ureteral double J indwelling by decreasing mean, as well as global encrustation.

TRIAL REGISTRATION

This trial was registered at www.clinicaltrials.gov under the name "Combined Use of a Medical Device and a Dietary Complement in Patient Urinary pH Control in Patients With an Implanted Double J Stent" with date 2nd November 2017, code NCT03343275, and URL.

Advances in Drug Delivery via Biodegradable Ureteral Stent for the Treatment of Upper Tract Urothelial Carcinoma

Drug eluting ureteral stent is an effective means for local drug delivery to the urinary tract. It can potentially solve a variety of upper urinary tract problems, such as stent-related urinary tract infections and discomfort, ureteral stricture, and neoplastic diseases. However, the release of drug elutes on the surface of biostable stents is unsustainable and uncontrollable. With the development of biomaterial science, the emergence of biodegradable ureteral stents (BUSs) provides a new approach for local drug delivery in the urinary tract. The drugs can be continuously released in a controlled manner from a drug-eluting BUS, when the stent degrades. Especially for the delivery of anti-tumor drugs, the stents can obviously improve the therapeutic effectiveness of the drugs by prolonging the contact duration of the drug and tumor cells. In addition, a secondary stent removal procedure can be avoided. The purpose of this review article is to provide an overview of anti-tumor drug-eluting BUSs and discuss the biomaterials and drug delivery systems of BUS that are currently being developed to deliver anti-tumor drugs for upper tract urothelial carcinoma.

A New Customized Ureteral Stent with Nonrefluxing Silicone End-piece to Alleviate Stent-related Symptoms in Malignant Diseases

OBJECTIVE

To evaluate the stent-related symptoms using a new customized ureteral stent with a nonrefluxing silicone end-piece.

METHODS

By decreasing the amount of material within the bladder, it should be possible to attenuate the stent-related symptoms. To minimize the amount of material, 17 consecutive patients already fitted with a double-pigtail stent for malignant ureteral obstruction agreed to be fitted with a customized stent where the bladder loop was replaced by a nonrefluxing silicone end-piece. The ureteral stent symptom questionnaire was prospectively administered to patients at baseline with double-pigtail stent and Day 15 after customized stent placement.

RESULTS

No difficulty in the placement of the customized stent was encountered. No stent failure, no dislodgment and no calcification were observed 6 months after stenting. The scores for the main domain "Urinary symptoms" (34.4 ± 3.6 vs 23.0 ± 7.0; P = .0004) and the question "Global quality of life" (4.4 ± 2.0 vs 2.4 ± 2.1; P = .01) were significantly decreased by the replacement of the double-pigtail stent by the customized stent.

CONCLUSION

The customized ureteral stent may constitute an improvement in the field of stent-related symptoms and seems fit for use in its current shape. Studies exploring and exploiting new concepts are greatly required to reduce stent-related symptoms in all patients including those with cancer.