Percutaneous nephrostomy versus ureteral stent in hydronephrosis secondary to obstructive urolithiasis:A systematic review and meta-analysis

Objective: To assess if there is a preferable intervention between retrograde ureteral stent (RUS) and percutaneous nephrostomy (PCN) tube, in cases of upper urinary tract stone obstruction with complications requiring urgent drainage, by evaluating outcomes regarding urinary symptoms, quality of life (QoL), spontaneous stone passage, and length of hospital stays, since there is no literature stating the superiority of one modality over the other.Methods: We searched MEDLINE and other sources for relevant articles in June 2019 without any date restrictions or filters applied. The selection was done first by the title and abstract screening and then by full-text assessment for eligibility. Only randomized controlled trials or cohort studies in patients with hydronephrosis secondary to obstructive urolithiasis that presented comparative data between PCN and RUS placement concerning at least one of the defined outcome measures were included. Lastly, MEDLINE database and PubMed platform were screened again using the same terms, from June 2019 until November 2022.Results: Of 556 initial articles, seven were included in this review. Most works were considered of moderate-to-high quality. Three studies regarding QoL showed a tendency against stenting, even though only one demonstrated statistically significant negative impact on overall health state. Two works reported significantly more post-intervention urinary symptoms in stenting patients. One article found that PCN is a significant predictor of spontaneous stone passage, when adjusted for stone size and location. Findings on length of hospital stays were not consistent among articles.Conclusion: PCN appears to be the intervention better tolerated, with less impact on the patient’s perceived QoL and less post-operative urinary symptoms, in comparison with RUS. Nevertheless, further studies with larger samples and a randomized controlled design are suggested.

Compression Mechanical Performance Simulation and Parameter Optimization of Degradable Ureteral Stent Based on ABAQUS

The compression performance of a degradable ureteral stent is analyzed and the parameters are optimized by a finite element modeling method.The degradable ureteral stent explored in this paper is developed from poly(glycolic acid)(PGA)and poly(lactic-co-glycolic acid)(PLGA)degradable materials.Based on the actual measurement of fabric structure parameters,the three-dimensional model of the stent is established with the help of the modeling software.The finite element analysis software is used to simulate the compression process of the degradable ureteral stent.The parameters of materials,interactions and boundary conditions are set according to the compression environment of the stent for modeling and simulation.On this basis,the friction coefficient of yarns,the yarn radius,and the braided angle of the stent are further compared.The comparison test is carried out by a single variable.The experimental results show that the change of yarn friction coefficient has little influence on the compressive stress,while the yarn radius and the braided angle of the stent have a great influence on the compressive stress.

Understanding the corrosion of Mg alloys in in vitro urinary tract conditions: A step forward towards a biodegradable metallic ureteral stent

Ureteral stents play a fundamental role in modern time urology. However, following the deployment, stent-related symptoms are frequent and affect patient health and quality of life. Using biodegradable metals as ureteral stent materials have emerged as a promising strategy, mainly due to the improved radial force and slower degradation rate expected. Therefore, this study aimed to characterize different biodegradable metals in urinary tract environment to understand their propensity for future utilization as base materials for ureteral stents. The corrosion of 5 Mg alloys - AZ31, Mg-1Zn, Mg-1Y, pure Mg, and Mg-4Ag - under simulated urinary tract conditions was accessed. The corrosion layer of the different alloys presented common elements, such as Mg(OH)_(2), MgO, and phosphate-containing products, but slight variations in their chemical compositions were detected. The corrosion rate of the different metals varied, which was expected given the differences in the corrosion layers. On top of this, the findings of this study highlighted the significant differences in the samples' corrosion and corrosion layers when in stagnant and flowing conditions. With the results of this study, we concluded that Mg-1Zn and Mg-4Ag presented a higher propensity for localized corrosion, probably due to a less protective corrosion layer;Mg-4Ag corroded faster than all the other four alloys,and Mg-1Y stood out due to its distinct corrosion pattern, that showed to be more homogeneous than all the other four samples, making this one more attractive for the future studies on biodegradable metals.

Ureteral stents in urolithiasis

Ever since the ureteral stent design was fitted with a curl on both sides to prevent it from migrating up or down the ureter some 40 years ago,its use has gained tremendous momentum,aiding in the rise and evolution of endourology and has confidently kept its place in modern time urology.Over the past four decades,several designs,coating and biomaterials have been developed,trying to reduce infection,encrustation and other stent related symptoms.As the ideal stent has not yet been discovered,different ways of helping patients with their complaints have been researched.This review will cover these aspects of stent use in urolithiasis.

Effect of Preoperative Double-J Ureteral Stenting before Flexible Ureterorenoscopy on Stone-free Rates and Complications

The effect of preoperative Double-J(DJ)ureteral stenting before flexible ureterorenoscopy(FURS)in the treatment for urinary stones was evaluated.We retrospectively enrolled 306 consecutive patients who underwent FURS from Jan.2014 to Dec.2017.All the patients were classified into two groups according to whether they had DJ ureteral stenting before FURS.Baseline characteristics(age,sex,stone location,stone size,surgical success rate,operation time,stone-free rate of the first day after surgery,stone-free rate of the first month after surgery,total complication rate)were compared using Chi-square test for categorical variables and Kruskal-Wallis test for continuous variables.In total,306 patients were included in this study.The group of DJ stenting before FURS included 203(66.3%)patients,and non-DJ stenting before FURS was observed in 103(33.7%)patients.The group of DJ stenting before FURS was significantly associated with a shorter operation time(53.8 vs.59.3 min,P<0.001),a higher stone-free rate of the first day after surgery(69.0%vs.51.5%,P=0.003).However,statistical significant differences were not found in the age,sex,stone location,stone size,surgical success rate,stone-free rate of the first month after surgery(89.2%vs.81.6%,P=0.065)and total complication rate(5.4%vs.9.7%,P=0.161)between the two groups.Preoperative DJ ureteral stenting before FURS could reduce the operation time and increase stone-free rate of the first day after surgery.However,it might not benefit the stone-free rate of the first month after surgery and reduce the complication rate.Preoperative DJ stenting should be not routinely performed.

Use of percutaneous nephrostomy and ureteral stenting in management of ureteral obstruction

The management options for ureteral obstruction are diverse, including retrograde ureteral stent insertion or antegrade nephrostomy placement, with or without eventual antegrade stent insertion. There is currently no consensus on the ideal treatment or treatment pathway for ureteral obstruction owing, in part, to the varied etiologies of obstruction and diversity of institutional practices. Additionally, different clinicians such as internists, urologists, oncologists and radiologists are often involved in the care of patients with ureteral obstruction and may have differing opinions concerning the best management strategy. The purpose of this manuscript was to review available literature that compares percutaneous nephrostomy placement vs ureteral stenting in the management of ureteral obstruction from both benign and malignant etiologies.

Ureteral Stent Fragmentation:a Case Report and Review of Literature

SINCE the introduction of double J stents in 1978, ureteral stents have become an integral tool in treating ureteral obstruction from calculi and other causes.1 Owing to the widespread usageof indwelling ureteral catheters, a number of possible complications such as migration, infection, pyelonephritis, breakage, encrustation, stone formation, and ureteral stents fragmentation have been noted.2 Of all the complications, ureteral stent fragmentation was sporadically reported and believed to be rare. Here we present a case of fragmentation of a new type of double J stent, which was used to provide free drainage to the bladder after balloon dilation.

Ureteral Stenting Following Uncomplicated Ureteroscopy for Ureteric Stones: A Randomized Controlled Trial

Objective: The objective is to assess the benefits and adverse effects of routine ureteral stenting after uncomplicated ureteroscopic lithotripsy. Material and Methods: Sixty patients with ureteric calculi amenable to ureteroscopic lithotripsy were randomized to an unstented (30 patients) or a stented (30 patients) treatment group, standard ureteroscopic lithotripsy done using 8 French semirigid ureteroscope, and pneumatic lithotripter used to fragment the stones. They were followed up for postoperative flank pain, lower urinary tract symptoms (LUTS) and hematuria. Results: There was no significant difference in the mean age (stenting 37.8 year and 33.5 year unstenting) of patients, gender and stone size in both groups. No significant difference in the mean flank pain within 3 days postoperative, while at day 14 postoperative flank pain for stenting group was significant (P = 0.03). Dysuria and urgency were high for stenting group (P = 0.002 and 0.011). Hematuria within 3 and 14 days was higher in the stenting group. Conclusion: After uncomplicated ureteroscopy, stents can be safely omitted. Unstented patients have significantly fewer LUTS, haematuria and flank pain.

In vitro Degradation Study of a Braided Thin-Walled Biodegradable Ureteral Stent

The main disadvantage of conventional ureteral stents commonly used to provide urinary drainage after urological practice is that the patients have to undergo a secondary surgical procedure to remove stents. A new braided thin-walled biodegradable ureteral stent composed of PGA （ polyglycolic acid） and PLGA （ eopolymer of polylactic and polygiycolic acid） mnltifilaments was evaluated in v/tro in this study. In vitro degradation was performed in artificial urine with pH of 5.8 and the temperature of 37~C. The mass loss, mechanical properties, and morphology were observed at different degradaing time intervals of 0, 1, 2, 3, 4, and 5 weeks. The stent had a thinner wail than those of other degradable stents and provided better mechanical properties. The braided thin-walled biodegradable ureteral stents began to degrade after 2 weeks. At the week of 5, the stents were fully degraded. The degradative process of stents is smooth and well controlled.

Peak stent discomfort occurs early and ureteral stent with distal loop design has less paineA pilot prospective randomised singleblinded trial over 2 weeks

Objectives:The Polarisloop ureteric stent reduces the severity of stent discomfort by minimising stent material in the bladder.Early impact of ureteral stenting on quality of life(QoL)within 1 week remains unclear.The usefulness of the patient-administered ureteral stent symptoms questionnaire(USSQ)during this period of stent insertion was assessed.In this pilot single-blinded prospective randomised study,we investigate 1)the presence of early(within the 1st week)stent discomfort via the visual analog scale(VAS);2)determine the QoL of the loop stent against conventional stent.Methods:Forty adults requiring retrograde unilateral ureteral stent placements were enrolled.Patients with single ureteric stone or benign stricture were selected.Patients were randomised in 1:1 ratio to the loop and pigtail arm.The USSQ was administered before placement(baseline),USSQ and VAS were administered on Day 3,7,and 14.Results:There were no significant differences between the USSQ scores.Median pain scores on Day 3 were lower in the loop stent group(2.9 vs.4.0,pZ0.047).There was a significant reduction in pain from Day 3e7(0 vs.1,pZ0.016)in the pigtail group.Conclusions:Our results suggest that peak stent discomfort occurs but resolves quickly within 1 week of post-stent insertion.The loop stent offers a better pain profile compared with conventional stents at Day 3 but no difference in QoL.The loop stent reduces early pain experience post-stent insertion and may have a role in the care of patients who experience significant stent discomfort previously.

Metallic ureteral stent in restoring kidney function: Nine case reports

BACKGROUND Retroperitoneal fibrosis is an exceptionally rare disease characterized by proliferation of fibrous tissue and inflammation in the retroperitoneum.It features many symptoms in the kidneys and in other organs and usually leads to ureteral obstruction.CASE SUMMARY Here we present 9 consecutive cases of idiopathic retroperitoneal fibrosis(IRPF)in patients who presented to the Department of Nephrology or Department of Rheumatology,Xuanwu Hospital,Capital Medical University,Beijing,China,between January 2012 and June 2017 with ureteral obstruction due to external compression of the ureter that led to hydronephrosis and kidney dysfunction.Computed tomography imaging was used to identify hydronephrosis and ureteral obstruction and to evaluate kidney function.Each patient was diagnosed with IRPF based on clinical observation and computed tomography examination results.To restore kidney function,a retrograde metallic stent was placed in the ureter under X-ray guidance 2 d after each patient’s admission.No perioperative complications occurred in any patient,but postoperative complications occurred in two patients as follows:Patient 2 had stent migration and repeated metallic stent infections that resolved with treatment;and patient 4 had postoperative hematuria because he resumed normal activities too soon after stent placement(contrary to instruction).Placement of the metallic ureteral stents provided relief from ureteral obstruction and restored kidney function in all patients.CONCLUSION Our 9-case series underscores the utility and efficacy of applying the Resonance®metallic ureteral stent to treat ureteral obstruction in patients with IRPF.For all retroperitoneal fibrosis cases in our series,ureteral stents provided effective relief and were shown to reduce the incidence rate of perioperative and postoperative complications.

Does delaying ureteral stent placement lead to higher rates of preoperative acute pyelonephritis during pregnancy?

BACKGROUND Pregnancy with renal colic may cause pyelonephritis,decreased renal function,systemic infection and even shock in pregnant women,and cause premature birth and other adverse pregnancy outcomes.When surgery is necessary,the relationship between timing of the operation and the outcome of the mother and child are not known.AIM To investigate the association between time to ureteral stent placement and clinical outcomes of patients with renal colic during pregnancy.METHODS In this retrospective study,pregnant women with renal colic who underwent surgery were studied.Maternal preoperative acute pyelonephritis(PANP),pregnancy outcome,and length of hospital stay(LOS)were compared between the two groups.RESULTS 100 patients were included in the analysis,median age was 30 years.Median time to ureteral stent placement was 48 h(interquartile range,25-96 h),and 32 patients(32%)were diagnosed with PANP.PANP was closely related to hospitalization costs,re-admission to the hospital due to urinary tract infection after surgery and premature delivery.Multivariate analysis found that stone location and time from pain to admission were related to PANP.CONCLUSION Both early and delayed surgery are safe and effective for the treatment of renal colic during pregnancy.Early surgery may be superior to a delayed procedure due to shorter LOS.For pregnant patients with renal colic,delayed surgery within 48 h is not related to the clinical outcome of the mother and child.However,the time from pain to hospital admission was related to PANP.

Forgotten Ureteral Stents in a Tertiary Hospital in Accra and a Review of Endourological Management of Upper Urinary Tract Pathologies in the West Africa Sub-Region

Background: Forgotten ureteral stent is defined as prolong indwelling ureteral stent whose function is no longer desired. Ureteral stents are used in the management of upper urinary tract pathologies. Prolonged indwelling ureteral stents may be complicated by urosepsis or renal failure, encrustation, stone formation, spontaneous fracture which may either be retained or voided in the urine (stenturia). Hitherto, these complications were managed by open procedures alone in our center. We report our recent experience in endourology with the management of three cases of forgotten ureteral stents with durations of ten years and two years (two cases) and review endourological practice in West Africa. Conclusion: Although encrusted stents can be managed successfully by minimally invasive approaches in the majority of cases, the best treatment is prevention. Urology units should have preferably an electronic stent register such that when the time for removal is due, the patient's name and details are flagged red. If electronic register is not available, then a hard paper/book register should be made to prevent situations of forgotten stents. Also, efforts must be made to improve endourological services in the West Africa subregion to allow patients to have the benefit of endourology in the management of upper urinary tract pathologies including that of stones originating from an encrusted or fractured forgotten ureteral stent.

Multi-objective structural optimization and degradation model of magnesium alloy ureteral stent

Background:Mg alloys have attractive properties,including biocompatibility,biodegradability,and ideal mechanical properties.Moreover,Mg alloys are regarded as one of the promising candidates for manufacturing ureteral stents.This study proposed a multi-objective optimization method based on the Kriging surrogate model,NSGA-III,and finite element analysis to improve the degradation performance of Mg alloy ureteral stents.Methods:The finite element model for the degradation of Mg alloy ureteral stents has been established to compare the degradation performance of the stents under different parameters.Latin hypercube sampling was adopted to generate train sample points in the design space.Meanwhile,the Kriging surrogate model was constructed between strut parameters and stent degradation behavior.The NSGA-III was utilized to determine the optimal solution in the global design space.Results:The optimized stent achieved 5.52degradation uniformity(M),10degradation time(DT),and 4work time(FT).The errors between the Kriging surrogate model and the finite element calculation results were less than 6%.Conclusion:The optimized stent achieved better degradation performance.The degradation behavior of stents was dependent on the design parameters.The multi-objective optimization method based on the Kriging surrogate model and finite element analysis was effective in stent design optimization problems.

Stents for malignant ureteral obstruction

Malignant ureteral obstruction can result in renal dysfunction or urosepsis and can limit the physician’s ability to treat the underlying cancer.There are multiple methods to deal with ureteral obstruction including regular polymeric double J stents(DJS),tandem DJS,nephrostomy tubes,and then more specialized products such as solid metal stents(e.g.,Resonance Stent,Cook Medical)and polyurethane stents reinforced with nickel-titanium(e.g.,UVENTA stents,TaeWoong Medical).In patients who require long-term stenting,a nephrostomy tube could be transformed subcutaneously into an extra-anatomic stent that is then inserted into the bladder subcutaneously.We outline the most recent developments published since 2012 and report on identifiable risk factors that predict for failure of urinary drainage.These failures are typically a sign of cancer progression and the natural history of the disease rather than the individual type of drainage device.Factors that were identified to predict drainage failure included low serum albumin,bilateral hydronephrosis,elevated C-reactive protein,and the presence of pleural effusion.Head-to-head studies show that metal stents are superior to polymeric DJS in terms of maintaining patency.Discussions with the patient should take into consideration the frequency that exchanges will be needed,the need for externalized hardware(with nephrostomy tubes),or severe urinary symptoms in the case of internal DJS.This review will highlight the current state of diversions in the setting of malignant ureteral obstruction.

Ultrathin,elastic,and self-adhesive nanofiber bio-tape:An intraoperative drug-loading module for ureteral stents with localized and controlled drug delivery properties for customized therapy

During the postoperative management of urinary diseases,oral or intravenous administration of drugs and implanting ureteral stents are usually required,making localized drug delivery by ureteral stent a precise and effective medication strategy.In the traditional drug loading method,the drug was premixed in the implants in production lines and the versatility of drugs was restricted.However,the complex situation in the urinary system fails the possibility of finding a“one fits all”medication plan,and the intraoperative drug-loading of implants is highly desired to support customized therapy.Here,we designed an ultrathin(8μm),elastic,and self-adhesive nanofiber bio-tape(NFBT)that can easily encapsulate drugs on the stent surface for controllable localized drug delivery.The NFBT exhibited high binding strength to a ureteral stent,a sustained release over 7 d in PBS for hydrophilic drug,and a zero-order release curve over 28 days for the hydrophobic drug nitrofurantoin(NFT).Further in vivo experiments using a porcine ureteral tract infection model demonstrated that NFBT loaded with NFT could significantly reduce the bacterial concentration in urine.The total amount of NFT delivered by the NFBT was about 2.68 wt%of the recommended dose for the systemic administration.

In vivo study on heparin/poly-L-lysine-copper coating for surface functionalization of ureteral stent

Polyurethane(PU)ureteral stents are used in clinics to maintain the ureteral patency.Due to biofilm formation and encrustation complications,long-term clinical usage has been limited.It is therefore necessary to develop an effective response to this unmet medical need.A heparin/poly-L-lysine/copper(NPs)coating was developed in our previous work that showed the effect of preventing infection and encrustation in vitro.In this work,a further study was conducted by grafting NPs on clinical ureteral stents that then were implanted into the infectious bladders of Wistar rats to investigate the effects of nanoparticles on bacterial growth and crystal deposition in vivo.It was found that decreased numbers of adherent microbes,urease amount splitting by bacteria,and deposited crystals were observed on the NPs stents with significant differences in comparison with PU stents.Besides,histological analysis showed that the NPs stents decreased the host tissue inflammation in close relation to the decrease biofilm formation and encrustation after 28 days of implantation.

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 antiencrustation 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.

Case of Fatal Air Embolism during Double‑J Ureteral Stent Placement

Air embolism is a severe and fatal complication,but it is very rare during transurethral surgery.This report describes a case of air embolism during double‑J ureteral stent placement in a 45‑year‑old woman.During ureteroscopy,a sudden decrease in oxygen saturation and end‑expiratory carbon dioxide pressure and cyanosis of the face were observed.Subsequent echocardiography confirmed an air embolism by detecting bubbles in the heart.Despite resuscitative measures,the patient died rapidly.Detailed autopsy was performed to clarify the cause of death and the route of air entering into the circulatory system.The report presented here reminds urologists and pathologists that air embolism can occur during double‑J ureteral stent placement and offers some suggestions regarding identification of air embolism at autopsy.

Acute kidney injury due to bilateral ureteral obstruction in children

Bilateral ureteral obstruction in children is a rare condition arising from several medical or surgical pictures.It needs to be promptly suspected in order to attempt a quick renal function recovery.In this paper we concentrated on uncommon causes of obstruction,with the aim of giving a summary of such multiple,rare and heterogeneous conditions joint together by the common denominator of sudden bilateral ureteral obstruction,difficult to be suspected at times.Conversely,typical and well-known diseases have been just run over.We considered pediatric cases of ureteral obstruction presenting as bilateral,along with some cases which truly appeared as single-sided,because of their potential bilateral presentation.We performed a review of the literature by a search on Pub Med,Cross Ref Metadata Search,internet and reference lists of single articles updated to May 2014,with no time limits in the past.Given that we deal with rare conditions,we decided to include also papers in non-English languages,published with an English abstract.For the sake of clearness,we divided our research results into 8 categories:(1) urolithiasis;(2) congenital urinary tract malformations;(3) immuno-rheumatologic causes of ureteral obstruction;(4) ureteral localization of infections;(5) other systemic infective causes of ureteral obstructions;(6) neoplastic intrinsic ureteral obstructions;(7) extrinsic ureteralobstructions; and(8) iatrogenic trigonal obstruction or inflammation.Of course,different pathogenic mechanisms underlay those clinical pictures,partly wellknown and partly not completely understood.