Recent advances in ureteral stents:

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.

Renal function is associated with prognosis in stent-change therapy for malignant ureteral obstruction

Purpose

The authors performed this study to investigate the risk factors for predicting stent failure and to evaluate its impact on prognosis.

Materials and Methods

Between January 2002 and March 2017, we retrospectively reviewed 117 consecutive patients who underwent retrograde ureteral stenting and exchanging at least once every 3 months for malignant ureteral obstruction. The patients were classified according to their pre-stenting chronic kidney disease (CKD) stage. The factors affecting stent failure were analyzed using a logistic regression model. Overall survival (OS) was estimated, and the prognostic significance of each variable was estimated using Cox proportional-hazards regression modeling.

Results

Before stenting, 91 patients were CKD stages 1–3 and 26 patients were CKD stages 4–5. These two groups differed significantly only in pre-stenting estimated glomerular filtration rate (eGFR), bilateral obstruction, and pre-stenting pyuria. Among the 117 patients, stent failure occurred in 30 patients (25.6%), and there were no differences between the groups. Pre-stenting pyuria and post-stenting complications were significant predictors of stent failure. There were 79 deaths in total, including 56 in the CKD stages 1–3 group and 23 in the CKD stages 4–5 group. In the multivariate analysis predicting patient OS, pre-stenting eGFR and post-stenting disease progression were significant factors.

Conclusions

Internal ureteral stenting was effective for maintaining renal function in malignant ureteral obstruction. However, it did not restore renal function, which is related to the prognosis of the patients. Therefore, to improve patients' renal function and prognosis, patients who require stenting must be quickly recognized and treated.

A Randomized Controlled Trial to Compare the Safety and Efficacy of Tadalafil and Tamsulosin in Relieving Double J Stent Related Symptoms

Objectives. To evaluate the safety and efficacy of Tadalafil and Tamsulosin in treating Double J stent related symptoms. Methods. In a prospective study, 161 patients with DJ related symptoms were randomized into 3 groups: Group A patients (54), Group B patients (53), and Group C patients (54). They were given Tadalafil, Tamsulosin, and placebo, respectively, at 1st week till removal of DJ stent at 3rd week. All patients completed Ureteral Stent Symptom Questionnaire (USSQ) at 1st week and at 3rd week. The statistical significant difference among groups was determined by the t-test, Kruskal-Wallis test and multivariate analysis were used to assess association of the variables within the three groups, and the level of significance was set at P < 0.05. Results. Tadalafil and Tamsulosin were comparable in relieving urinary symptoms, general health, and work performance (OR = 0.65, 1.8, and 0.92). But Tadalafil was more effective in relieving body pain, sexual problems, and additional problems than Tamsulosin (OR = 5.95, 19.25, and 2.69) and was statistically significant as P < 0.05. Conclusion. Tadalafil was as effective as Tamsulosin in relieving urinary symptom but more effective in relieving sexual symptoms and body pain.

Role of α-blockers in the treatment of stent-related symptoms: a prospective randomized control study

OBJECTIVE

To properly use the Ureteric Symptom Score Questionnaire (USSQ) to evaluate, in a randomized control study, the effect of 2 different α-blockers in improving symptoms and quality of life in patients with indwelling ureteral stents.

METHODS

After institutional review board approval, 150 consecutive patients with a double-J ureteral stent inserted after extracorporeal shockwave lithotripsy (ESWL) or ureteroscopic stone treatment were randomly assigned to receive tamsulosin 0.4 mg, alfuzosin 10 mg, or placebo. The validated USSQ was completed 1 and 4 weeks after stent insertion and 4 weeks after stent removal. The Kruskal-Wallis test for independent samples for non-normally distributed ordinal variables, chi-square to compare proportions or differences, and 1-way analysis of variance (ANOVA) for independent samples to compare for differences in case of continuous variables were used for statistical analysis of the results.

RESULTS

Patients receiving α-blockers expressed an overall statistically significant lower urinary (P <.001), pain (P <.001 with stent in situ), and general health index (P <.002) scores. Sexual life and quality of life were also positively influenced. Quality of work was not influenced. No patients had to discontinue medication because of side effects or underwent stent removal before the due date. There was no difference in various outcomes between the 2 α-blockers.

CONCLUSION

Stent-related morbidity is a reality in the majority of patients. Simple medication, such as α-blockers, reduce stent-related symptoms and the negative impact on quality of life. It seems that stent-related symptom improvement is independent to the type of α-blocker.

Braided thin-walled biodegradable ureteral stent: preliminary evaluation in a canine model

OBJECTIVES

To evaluate a novel designed degradable ureteral stent.

METHODS

A total of 24 male Beagles, each with bilateral stents implanted (a biodegradable ureteral 4.5-Fr stent and a standard 4-Fr biostable stent) were divided into four groups. Intravenous pyelography, B-mode ultrasonography, and blood and urine tests were carried out before the procedure (0 weeks), and at 1-, 2-, 3- and 4-week intervals. Meanwhile, the mechanical characteristics of stents were tested, and scanning electron microscopy images of the biodegradable braided stents were obtained at different time-points postoperatively. In addition, histopathological changes were compared between the two different stents.

RESULTS

All biodegradable braided stents began degrading at 1 week, and had completely degraded by 4 weeks. Hydronephrosis was equivalent during the first 2 weeks, but less with the biodegradable stents than with the control biostable stents at 3 and 4 weeks. Preoperative and postoperative blood and urine results were similar. The mechanical properties of the biodegradable stents were better than conventional biostable stents. Scanning electron microscopy images obtained at different weekly intervals showed that stents degraded in a predictable fashion. Histological testing of the urinary tract showed that the stent-related tissue reactivity of the two different stents were similar.

CONCLUSIONS

Our novel braided thin-walled biodegradable stents provide temporary renal drainage as good as commercially available biostable stents. They also have good biocompatibility and physical characteristics. Therefore, they might have clinical application.

Thermo-expandable metallic urethral stents for managing recurrent bulbar urethral strictures: To use or not?

Objectives

To assess the role of temporary thermally expandable urethral stents in maintaining urethral patency in patients with a recurrent bulbar urethral stricture.

Patients and methods

Twenty-three men with a recurrent bulbar urethral stricture after several attempts at direct visual internal urethrotomy (DVIU) and/or failed urethroplasty were managed with a thermally expandable, biocompatible nickel–titanium alloy urethral stent (Memokath® MK044, Pnn Medical, Kvistgaard, Denmark). The stents were applied by a special mounting device via a rigid urethroscope after DVIU. All patients were followed using plain radiography, uroflowmetry and urine analysis every 3 months for 1 year, and then every 6 months.

Results

The mean (SD) age of the patients was 55.4 (7.3) years and the mean (SD) stricture length was 3.6 (1.2) cm. All patients tolerated the stent, with minimal discomfort in some patients. Four patients (17%) had urinary tract infections, three (13%) had haematuria, three (13%) had obstructed stents due to encrustation, in five (22%) the stent migrated, and two patients had no delayed complications. The mean (SD) follow-up was 17.4 (6.1) months.

Conclusion

Urethral stenting with nickel–titanium alloy thermally expandable stents can be an acceptable temporary procedure for patients with recurrent bulbar urethral strictures who are unfit for or who refuse urethroplasty. However, they have limitations; the search for an ideal urethral stent continues.

Palliative care of malignant ureteral obstruction with polytetrafluoroethylene membrane-covered self-expandable metallic stents: initial experience

Purpose

We assessed the efficacy and safety of insertion of a polytetrafluoroethylene membrane-covered self-expandable metallic stent (UVENTA stent) for palliation of malignant ureteral obstruction on the basis of our early results.

Materials and Methods

Eighteen patients underwent UVENTA stent insertion for extrinsic malignant ureteral obstructions of 20 ureters. The UVENTA stents were deployed retrogradely under cystoscopy and fluoroscopy. Candidates for the procedure had preexisting double-J stents that were nonfunctional or caused excessive bladder irritation. We recorded the success and patency rate in addition to any complications associated with the procedure.

Results

The mean length of obstruction was 10.6 cm (range, 2 to 20 cm). Two ureters were obstructed in the upper ureter, 9 in the lower ureter, and 9 in multiple levels of ureter. Simultaneous balloon dilation was performed in 12 ureters. UVENTA stents were successfully inserted in all patients. No obstruction of the UVENTA stents occurred during the mean follow-up period of 7.3 months (patency rate 100%), but de novo ureteral obstruction developed in 4 ureters. There were no instances of stone formation, hyperplastic reaction, encrustation, or migration. Abnormally elevated serum creatinine decreased to normal levels and hydronephrosis gradually resolved during the 4 weeks after UVENTA insertion. No significant complications developed except for transient and self-limiting hematuria and mild lower abdominal pain.

Conclusions

UVENTA stents may relieve malignant ureteral obstruction safely and easily. Long-term follow-up is necessary to assess the role of this stent in the treatment of malignant ureteral obstruction.

Ureteral stent discomfort: Etiology and management

Objectives:

To review the evidence-based literature on the causes, characteristics, and options to manage double J stent-related symptoms.

Methods:

We performed a Medline database assessment on papers that investigated the prevalence, mechanisms, risk factors, bothersome and management of double-J stent-related symptoms. Articles in English were reviewed and summarized.

Results:

Stent-related symptoms have a high prevalence and may affect over 80% of patients. They include irritative voiding symptoms including frequency, urgency, dysuria, incomplete emptying; flank and suprapubic pain; incontinence, and hematuria. Assessment tools are important to determine their intensity and allow for comparisons between different points in the timeline. The Urinary Stent Symptom Questionnaire (USSQ) is the most proper tool used for this purpose. Management should be focused on the prevention and management of symptoms. In this sense, research has focused on new materials and stent designs that would be more compatible to the physiologic properties of the urinary tract and medications that can ameliorate the sensitivity and motor response of the bladder.

Conclusions:

Stent-related symptoms are very common in the Urological clinical setting. It is of major importance for the urologist to understand their physiopathology and to be familiar with ways to avoid or manage them.

Introduction to biodegradable polylactic acid ureteral stent application for treatment of ureteral war injury

OBJECTIVE

• To study the operability and effectiveness of a biodegradable ureteral stent for clinical treatment of ureteral war injury using a canine model.

MATERIALS AND METHODS

• A device was designed and employed to generate firearm fragment wounds in unilateral ureters (on randomly chosen sides) of nine beagles (Group A). The wounded ureters were then debrided and sutured. • Intravenous pyelography (IVP) and radioactive renography were performed 40, 80 and 120 days postoperatively. In Group B, firearm fragment wounds were made to the bilateral ureters in nine beagles. A polylactic acid stent was placed unilaterally (on a randomly chosen side) whereas the ureter on the other side was debrided and sutured without stenting. • Both IVP and radioactive renography were performed 40, 80 and 120 days postoperatively. The operability and effectiveness of the biodegradable ureteral stent were studied thereafter.

RESULTS

• In Group A, hydronephrosis and hydroureter occurred and worsened postoperatively on the wounded sides in all nine beagles. The ratio of the renal partial concentration indices (RPCI) between the kidneys (unwounded side : wounded side) increased. • The ratio of the kidney washout half-time between the kidneys (unwounded side : wounded side) decreased. In Group B, neither hydronephrosis nor hydroureter was found postoperatively in the stented ureters but both occurred in the unstented ureters in all nine beagles. • The ratio of RPCI between kidneys (stented side : unstented side) increased whereas the kidney washout half-time ratio between the stented and unstented sides decreased. Differences were significant.

CONCLUSION

• In Group A, the new canine model for firearm fragment wounds was tested and proved to be operable and effective. In Group B, hydronephrosis and hydroureter were effectively prevented in ureters by biodegradable stent placement compared with the non-stented ureters where hydronephrosis and hydroureter occurred. The renal concentration capacity was effectively protected and the half-time of kidney washout was shortened.

Endourologic management of malignant ureteral obstruction: indications, results, and quality-of-life issues

Obstruction of the upper urinary tract is a problem commonly faced by practicing urologists. The constant evolution in endourology has effectively facilitated minimally invasive management of upper-tract obstruction. In a case in which malignancy is the cause of obstruction, however, the situation significantly changes. Questions arise regarding the need for relieving the obstruction, the means to accomplish this, and the benefits and drawbacks of each technique regarding both their efficacy and their impact on the patients well-being and the crucial issue of quality of life in the face of malignancy.

Current status of ureteroscopic treatment for urolithiasis

Intracorporeal treatment of urolithiasis is characterized by continuous technological evolution. In this review we present updated data upon the use of ureteroscopy for the management of urolithiasis. Novel digital flexible ureteroscopes are used in clinical practice. Ureteroscopic working tools are revolutionized resulting in safer and more efficient procedures. Special categories of stone patients such as pregnant women, children and patients on anticoagulation medication can now undergo uneventful ureteroscopy. Routine insertion of stents and access sheaths as well as bilateral ureteroscopy is still a controversial issue. Future perspectives include smaller and better instruments to visualize and treat a stone, while robotic ureteroscopy is becoming a fascinating reality.

[How to prevent tissue overgrowth and incrustation of metal stents in the urinary tract in patients with pelvic malignancy] b ]

At the current level of stent application in urology each irreversible urostasis contraindicated for surgical therapy implies consideration of indications for metal stent insertion. Stent incrustation which leads directly into a new uroobstruction is a characteristic complication of this method. Available experience in different uroobstructive conditions has shown that very different clinical aspects of stent usage may directly determine the possibility of their incrustation. Stent incrustation may occur in the early postprocedural course or several months later. After that, prevention of stent incrustation starts with postprocedural evaluation, selection of the stent type, and it is subsequently continued by insertion technique and lasts practically permanently after the insertion (infection control, promotion of diuresis and maintenance of normal urodynamics). Authors present own experianse in clinical aplication of metal stents in uroradiology strictures for period of last 15 years.

Pilot study evaluating ureteric physiological changes with a novel 'ribbon stent' design using electromyographic and giant magnetoresistive sensors

OBJECTIVE

To test a novel 'ribbon stent' (RS) design using an extraluminal bipolar electromyographic (EMG) and giant magnetoresistive (GMR) sensor system to characterize ureteric responses.

MATERIALS AND METHODS

In all, 11 female domestic pigs were divided into three groups to evaluate ureteric physiology: group 1 (two pigs) with an unstented ureter, group 2 (three) with a standard 6 F ureteric stent, and group 3 (six) with the RS. For all groups EMG/GMR evaluation was performed at baseline, immediately after stenting, and at 3 and 7 days after stenting. All pigs underwent standardized retrograde ureteropyelogram evaluation at these time points, and after the final evaluation the pigs were killed and the urinary tract was harvested for histopathological evaluation.

RESULTS

One stent in group 3 could not be deployed due to a problem with ureteric access. For groups 1, 2 and 3 the ureteric peristaltic activity was 109, 63, 72 events/h at baseline (P = 0.49); 61, 70, and 66 events/h immediately after stenting (P = 0.97); 66, 0, 8 events/h at 3 days after stenting (P = 0.002); and 61, 12, 0 events/h at 7 days after stenting, respectively (P = 0.049).

CONCLUSION

The RS was deployed easily and safely in the porcine model using a standard technique. As with a standard stent, there was significant ureteric dilation and decrease in peristalsis with the RS.

In vitro simulation of stent fracture mechanisms in ureteric nitinol wire stents

The ZebraStent is a new-concept lumen-less teflon-coated nitinol double-J wire-stent, designed to facilitate the passage of residual fragments after extracorporeal shock wave lithotripsy. In clinical practice we observed a small number of stent fractures. Hence, an experimental model was designed to simulate the physical forces that may lead to material fatigue of the stent. Flexion force was simulated by "half circular kidney mimicking structures" (HCKMS) into which the upper part of the stent was placed. All experiments were done for a minimum of 5 million cycles representing a stent indwelling time of 9 months, or until stent fracture, and simulating respiratory kidney movement. It was demonstrated that as the diameter of the HCKMS decreases, thus leading to an increased bending of the stent, the likelihood of stent fracture increased proportionally and occurred earlier. From our results it appears that stent fractures can be avoided by observing a maximum indwelling time of 6-8 weeks (which should suffice for the duration of a average SWL treatment), by choosing the correct (and shortest possible) stent length, and perhaps by manufacturer's modifications decreasing the stent's resistance to flexion. The ZebraStent concept remains appealing if it is considered as a short-term stent for post-SWL residual fragments.