Evaluation of a Polymeric Flap Valve-Attached Ureteral Stent for Preventing Vesicoureteral Reflux in Elevated Intravesical Pressure Conditions: A Pilot Study Using a Porcine Model

Triangular prismatic JJ stent does not cause more discomfort than tubular ones: a randomised controlled trial comparison

OBJECTIVE

To compare the stent-related symptoms (SRS) of three commonly used, readily accessible ureteric JJ stents after uncomplicated flexible ureteroscopic lithotripsy (FURL), in a prospective randomised controlled single-blind parallel-group study, in order to see whether structural difference might influence SRS.

PATIENTS AND METHODS

Patients undergoing FURL were randomised into three groups: the Cook Group received conventional 6 F Cook Universa Soft JJ stents as control, the Kang Yi Bo (KYB) Group received 6 F KYB anti-reflux JJ stents, and the Urovision Group received 7 F Urovision Visiostar ESWL JJ stents. The ureteric stent symptom questionnaire (USSQ) was administered at 1 week, 4 weeks (before stent removal), and 5 weeks (one week after stent removal as baseline evaluation) after stent insertion. Both raw and baseline-adjusted USSQ domain subscores at 1 week and 4 weeks were compared.

RESULTS

A total of 146 patients were included in the analysis. The KYB Group showed significantly lower P6&7 subscore yet higher urinary symptoms score 1 week and 4 weeks after stents insertion than both Cook and Urovision, whilst the Urovision Group achieved similar scores in most domains with Cook.

CONCLUSIONS

Although the KYB anti-reflux JJ stent might prevent vesicoureteral reflux, it induces significantly stronger urinary symptoms, both at 1 week or 4 weeks after stent insertion, with or without baseline correction. Despite the unique triangular prismatic shape, the Urovision Visiostar stent does not cause heavier urinary symptoms or pain compared to the conventional cylinder shape counterparts.

Antireflux Ureteral Stents Prevent Stent-Related Symptoms: A Meta-Analysis of Randomized Controlled Trials

Ureteral stents are widely used in urological care, but they are often associated with adverse stent-related symptoms (SRS), such as painful urination, elevated urinary frequency, and abdominal discomfort. Antireflux ureteral stents have been developed to reduce stent-related pain and reflux by minimizing vesicoureteral reflux (VUR). This systematic review and meta-analysis of randomized controlled trials (RCTs) was undertaken to assess the efficacy of antireflux ureteral stents in mitigating SRS compared to conventional urethral stents. Our study included a total of 269 cases from three RCTs. The meta-analysis showed that antireflux ureteral stents were significantly more effective than standard stents in reducing SRS, including stent-related pain (odds ratio (OR): 4.80, 95% CI: 2.77, 8.31, p <0.00001), severe stent-related pain (OR: 8.35, 95% CI: 2.12, 32.89, p=0.002), flank pain while urinating (OR: 5.98, 95% CI: 3.35, 10.68, p <0.00001), and severe flank pain while urinating (OR: 15.79, 95% CI: 2.91, 85.57, p=0.001). There was no significant difference in the rates of postoperative creatinine abnormality or postoperative hydronephrosis between the two groups. Therefore, antireflux ureteral stents are more effective than standard stents in reducing SRS. This suggests that antireflux ureteral stents should be considered for patients undergoing ureteral stenting.

Biodegradable Stent with mTOR Inhibitor-Eluting Reduces Progression of Ureteral Stricture

In this study, we investigated the effect of mTOR inhibitor (mTORi) drug-eluting biodegradable stent (DE stent), a putative restenosis-inhibiting device for coronary artery, on thermal-injury-related ureteral stricture in rabbits. In vitro evaluation confirmed the dose-dependent effect of mTORi, i.e., rapamycin, on fibrotic markers in ureteral component cell lines. Upper ureteral fibrosis was induced by ureteral thermal injury in open surgery, which was followed by insertion of biodegradable stents, with or without rapamycin drug-eluting. Immunohistochemistry and Western blotting were performed 4 weeks after the operation to determine gross anatomy changes, collagen deposition, expression of epithelial–mesenchymal transition markers, including Smad, α-SMA, and SNAI 1. Ureteral thermal injury resulted in severe ipsilateral hydronephrosis. The levels of type III collagen, Smad, α-SMA, and SNAI 1 were increased 28 days after ureteral thermal injury. Treatment with mTORi-eluting biodegradable stents significantly attenuated thermal injury-induced urinary tract obstruction and reduced the level of fibrosis proteins, i.e., type III collagen. TGF-β and EMT signaling pathway markers, Smad and SNAI 1, were significantly modified in DE stent-treated thermal-injury-related ureteral stricture rabbits. These results suggested that intra-ureteral administration of rapamycin by DE stent provides modification of fibrosis signaling pathway, and inhibiting mTOR may result in fibrotic process change.

Experimental Assessment of New Generation of Ureteral Stents: Biodegradable and Antireflux Properties

Objective: The aim was to assess a new biodegradable and antireflux intraureteral stent (BraidStent^®) design in a swine model after ureteral laparoscopic operation. Materials and Methods: A total of 24 female pigs underwent initial endoscopic, nephrosonographic, and contrast fluoroscopy assessment of the urinary tract. Afterward, unilateral ureteropelvic junction obstruction was performed by laparoscopic approach. Six weeks later, the animals underwent laparoscopic Anderson-Hynes pyeloplasty, and were randomly assigned to Group-I, in which a double-pigtail ureteral stent was inserted for 6 weeks, or Group-II, in which a BraidStent^®, a biodegradable intraureteral stent design, was placed. Follow-up assessments were performed at 3 and 6 weeks and 5 months. Results: In terms of therapeutic success, complete resolution was observed in 91.6% of Group-I animals and 88.8% in Group-II. No evidence of vesicoureteral reflux (VUR) was observed in Group-II animals and statistical significance in VUR and ureteral orifice damage were observed between groups. BraidStent^® degradation occurred in a controlled manner between 3 and 6 weeks, without obstructive fragments. Distal ureteral peristalsis was maintained in 66.6% and 83.3% in Group-II at 3 and 6 weeks of follow-up, respectively. In Group-II, the positive bacteriuria rate was 41.6% and the migration rate 25%. Pathological assessment showed a significant improvement in ureteral healing in Group-II vs Group-I. Conclusions: The results of this comparative study in a porcine model indicate that the intraureteral BraidStent performed similarly to conventional ureteral stents. It avoids complete ureteral length intubation, the adverse effects associated with conventional ureteral stents, and maintains a high level of distal ureteral peristalsis. Moreover, the BraidStent^® exhibited a predictable and controlled degradation rate and did not cause any obstructive fragments. However, further studies are needed to improve the anchoring system and reduce the risk of bacterial colonization.

Antireflux metal stent for biliary obstruction: Any benefits?

Endoscopic retrograde cholangiopancreatography with stent placement has been utilized as standard palliative management of distal malignant biliary obstruction (MBO). Compared to plastic stents, metal stents can provide longer-term relief of symptoms. When a large-bore metal stent is placed across the ampulla, patients are predisposed to the risk of cholangitis or stent dysfunction due to reflux of duodenal contents. To mitigate the risk of adverse events associated with the duodenobiliary reflux, efforts have been directed to development of antireflux metal stents (ARMSs). The antireflux property has been introduced through adding of an antireflux valve to the duodenal stent end. Evidence from clinical studies indicates that ARMSs may not only reduce the risk of ascending cholangitis during follow-up but also prolong stent patency time. However, the results of clinical studies testing ARMSs are inconsistent owing to heterogeneous designs of antireflux valves and stent bodies. Metal stents are increasingly indicated for benign biliary strictures and MBO in the setting of neoadjuvant chemotherapy, and therefore, research is warranted to evaluate ARMSs for those indications. Given that endoscopic ultrasound (EUS)-guided transmural biliary drainage has gained popularity, the optimal timing of placing an ARMS in relation to EUS-guided and percutaneous drainage should be investigated. Development and evaluation of ARMSs require an integrative approach utilizing phantom and animal models, measurements of stent mechanical properties, and in vivo functional study after stent placement. In this review article, we summarize updated evidence on ARMSs for MBO and discuss issues that should be addressed in future studies.

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.

Evaluation of a New Design of Antireflux-biodegradable Ureteral Stent in Animal Model

OBJECTIVE

To determine the effects in urinary tract of a new antireflux-biodegradable ureteral stent.

MATERIALS AND METHODS

Thirty six ureters belonging to 24 pigs were used. The study began with endoscopic, nephrosonographic, and fluoroscopic assessments. Three study groups of ureters (n = 12) were then specified. In group I, a biodegradable antireflux ureteral stent (BDG-ARS) was inserted in the right ureter of 12 pigs. Group II comprised the left ureter of the same animals, in which a double-pigtail stent was placed for 6 weeks. Group III ureters, belonging to 12 additional animals, were subjected to a ureteropelvic junction obstruction model that was then treated by endopyelotomy and stenting with BDG-ARS. Follow-ups were performed at 3-6 weeks and at 5 months.

RESULTS

None of the ureters receiving the BDG-ARS showed any evidence of vesicoureteral reflux (VUR). BDG-ARS degradation took place in a controlled and predictable fashion from the third to the sixth weeks, and no obstructive fragments appeared. No differences were found between groups I and II regarding passive ureteral dilation, but significant differences were found regarding VUR and ureteral orifice damage. BDG-ARS always maintained distal ureteral peristalsis. BDG-ARS in group III showed a 50% positive urine culture rate and a 16.6% migration rate in both BDG-ARS groups.

CONCLUSION

BDG-ARS avoided VUR and bladder trigone irritation. In addition, this polymer combination and stent-braided design achieved a consistent biodegradation rate with no obstructive fragments and with uniform degradation between the third and the sixth weeks. Consequently, morbidity associated with ureteral stents might be reduced.