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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.

Objectives: To assess the efficacy of a new anti-reflux intraureteral stent design in a swine model after minimally invasive treatment of ureteral stricture to reduce ureteral stent morbidity, previous to manufacture this design in a biodegradable fashion., Methods: Twenty-eight female pigs were included. The study began with a cystoscopic, nephrosonographic and contrast fluoroscopic assessment. Afterwards, obstructive uropathy model in right ureter was created. Obstruction was confirmed 6 weeks later and animals were randomly distributed into 2 groups. Group I underwent laser endopyelotomy and Group-II laparoscopic pyeloplasty A 3Fr anti-reflux intraureteral stent was placed 6 weeks. Follow-up evaluations were performed at 3-6 weeks. The final follow-up was completed at 5 months and included the aforementioned diagnostic methods and pathological study., Results: None of the study animals showed any vesicoureteral reflux signs or ureteral orifice injury. There were no urinomas or ureteric fistulas. The dislodgement rate was 10.7%. After 6 weeks of stenting, 71.4% of ureters showed ureteral peristalsis below the stent, and 100% at the final follow-up. After pathological assessment, no differences were shown at UPJ and healing in the incised area was correct in both groups., Conclusions: The new stent design avoids vesicoureteral reflux and bladder trigone irritation, consequently might reduce morbidity associated with double pigtail ureteral stents. This study also shows that it is only necessary temporary scaffolding the incised ureteral segment and not the entire length of the ureter after minimally invasive surgery. It is also necessary to manufacture this design in a biodegradable material, thus avoiding its removal.

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., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: To assess a new antireflux ureteral stent in animal model. The design expects to reduce morbidity associated with JJ ureteral stents., Materials and Methods: Twelve pigs were used in this study. The study began with a nephrosonographic assessment and excretory urography. Afterward, measurement of the internal diameter of both ureteropelvic junctions (UPJ) by retrograde ureteropyelography was performed. A 3 Fr (ARS group) antireflux ureteral stent was placed in the right kidney and a JJ 4 Fr (JJ group) stent was placed in the left. Follow-ups were performed at 3-6 weeks; both stents were removed at 6 weeks. The final follow-up was completed at 5 months. This includes the above-mentioned diagnostic methods and an anatomopathological study., Results: There were no significant differences in UPJ diameter evolution between groups. During renal damage assessment, significant differences at 3 and 6 weeks were found, renal dilation being larger in JJ group. The JJ group shows a higher degree of vesicoureteral reflux at 3 and 6 weeks. After assessment of ureteral orifice, significant differences between groups were found at 3 weeks, 6 weeks, and 5 months, damage being more severe in the JJ group. After anatomopathological assessment, no statistical significance at UPJ was observed. However, statistical significance was found at ureterovesical junction, damage being more severe in the JJ group., Conclusion: The antireflux ureteral stent design dilates the upper urinary tract without affecting ureterovesical junction, and consequently reduces morbidity associated with JJ ureteral stents. Therefore, its patient tolerance will possibly be better than that to existent designs., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: To evaluate a new design for a hybrid, dynamic, metallic ureteral stent that might avoid the formation of urothelial hyperplasia after ureteral metallic stenting in an experimental study., Materials and Methods: A total of 30 healthy female pigs were included in the present study, and an experimental obstructive uropathy in the right lumbar ureter was created in each pig. Obstruction was confirmed using percutaneous ultrasonography and retrograde ureteral pyelography and endoluminal ultrasonography 6 weeks after obstructive uropathy model creation. Then, the pigs were randomly distributed into 2 groups. Group 1 underwent standard metallic ureteral self-expanding internally covered stent deployment. Group 2 received a new hybrid metallic ureteral self-expanding internally covered stent. The follow-up period was 6 months., Results: The hybrid metallic ureteral self-expanding internally covered stent group had a lower rate of urothelial hyperplasia (21% vs 70%), reduced stent migration (6.6% vs 33.3%), and a greater success rate after 6 months of follow-up (86.6% vs 47%) compared with the standard metallic ureteral self-expanding internally covered stent deployment group, with statically significant differences between the 2 groups., Conclusion: Our experimental results have indicated that the use of the hybrid metallic ureteral self-expanding internally covered stent in ureteral strictures is feasible, safe, and effective and reduces the formation of urothelial hyperplasia without secondary interventions to maintain ureteral patency., (Copyright © 2013 Elsevier Inc. All rights reserved.)