Metallic Ureteral Stents versus Endoureterotomy as a Therapeutic Approach for Experimental Ureteral Stricture

Flexible ureteroscopy lithotripsy combined with metallic ureteral stents for the treatment of patients with upper urinary tract calculi

Flexible ureteroscopy lithotripsy (FURS) is the most common treatment for patients with upper urinary tract calculi (diameter, <2 cm). The purpose of this prospective study was to assess the efficacy of FURS combined with metallic ureteral stents (MUS) for the treatment of upper urinary tract calculi. A total of 38 patients with upper urinary tract calculi were recruited in the present study, to compare the efficacy between FURS and FURS combined with MUS (FURS-MUS). The results demonstrated that FURS-MUS shortened operative time compared with FURS (35.2±1.2 vs. 57.4±1.7 min, respectively; P<0.01). Data also indicated that the clearance rate in FURS-MUS and FURS was decreased from 94.5 and 87.8%, respectively (P<0.05). FURS-MUS treatment decreased the duration of postoperative hospital stay compared with FURS (4.5±0.5 vs. 7.5±1.5 days, respectively; P<0.05). These data demonstrated that FURS-MUS significantly increased postoperative inflammation score compared with FURS (6.2±0.8 vs. 4.2±1.0, respectively; P<0.05). The complication rate and blood loss exhibited no significant difference between FURS-MUS and FURS (complication rate, 6.5% vs. 5.9%, respectively; blood loss, 4.2% vs. 4.6%, respectively). FURS-MUS significantly decreased inflammatory cytokines and risk of sepsis, and improved readmission rate, stone recurrence and progression-free survival compared with patients treated with FURS. In conclusion, these data suggested that FURS-MUS may be an efficient, minimally invasive and reproducible operation for patients with upper urinary tract calculi.

New combined approach in metallic ureteral stenting to avoid urothelial hyperplasia: study in swine model

PURPOSE

We assessed the therapeutic value of a new treatment option for ureteral strictures that may avoid urothelial hyperplasia, which is the main cause of metallic stent failure.

MATERIALS AND METHODS

We used 24 pigs in this study. An experimental model of ureteral stricture was induced in all animals. Obstruction was confirmed by ultrasound and retrograde ureteropyelogram 6 weeks after model creation. The pigs were then randomly allocated to 2 experimental groups. Therapy involved placement of a 6 × 30 mm metallic ureteral covered stent in the ureteral stricture in group 1 and subsequent endoureterotomy at the ureteral segments adjacent to the 2 ends of the stent in group 2. A double pigtail stent was then deployed for 3 weeks. Completion studies 6 months after therapy included retrograde ureteropyelogram, endoluminal ultrasound and ureteroscopy to assess urothelial hyperplasia formation.

RESULTS

At the end of the study evidence of urothelial hyperplasia was seen in 50% of the pigs in group 1 and in 29% in group 2. Four and 2 cases of cranial stent migration in groups 1 and 2, respectively, were seen at 6 months. Hyperplasia and renal involvement were statistically significantly different between the groups with more damage in group 1 than in group 2.

CONCLUSIONS

Hyperplasia was markedly reduced when ureteral peristalsis was inhibited by endoureterotomy at the area of interaction between the stent and the ureter.

Analysis of ureteral stent compression force and its role in malignant obstruction

PURPOSE

Extrinsic ureteral obstruction can be a challenging entity for the urologist since half of the ureteral stents placed for malignant obstruction fail. We evaluated the resistance to radial compression of various stents.

MATERIALS AND METHODS

Silhouette(R) 4.6Fr, 6Fr and 8Fr, Sof-Curl Tecoflex 6Fr, Resonance 6Fr, Polaris Ultra 6Fr and 7Fr, and Percuflex 6Fr and 8Fr stents were tested. The force needed to compress the stent to 50% of its original external diameter was measured at 3 locations along the stent length, including proximal, middle and distal. Statistical analysis was performed.

RESULTS

Statistically greater force was required to compress the Resonance and Silhouette stents compared to all others tested. These results were maintained at all 3 locations along the stent. Only the Polaris 6Fr stent differed in resistance to compression along the stent length.

CONCLUSIONS

The significantly higher forces required to compress the Resonance and Silhouette stents may translate into improved success in patients with malignant ureteral obstruction.

Endourologic techniques for ureteropelvic junction obstruction therapy. Comparative animal study

PURPOSE

The aim of this work is to compare 3 endourologic techniques for treating a ureteropelvic junction (UPJ) obstruction. To accomplish this, we performed a study in a porcine animal specimen, in which we compared laparoscopic pyeloplasty that emerges as the future gold standard technique, with 2 endopyelotomy techniques.

MATERIAL AND METHODS

Twenty-four healthy large white female pigs were randomly divided in 3 groups-group I (laparoscopic pyeloplasty), group II (endopyelotomy-Acucise, Applied Medical, Rancho Margarita, CA), and group III (endoballoon rupture endopyelotomy). Percutaneous and endoluminal ultrasonographic and fluoroscopic studies were analyzed during the different phases of the study. The study was divided in 3 phases. First one included premodel documentation of normal urinary tract and laparoscopic UPJ obstruction induction. During second phase at 6 weeks later, diagnosis and endourologic treatment were carried out. Fifteen weeks after obstruction treatment, follow-up imaging studies and postmortem evaluation of all animals were performed.

RESULTS

After the sonographic and fluoroscopic assessment, we determined the percentage of success rate for each technique-with an 87.5% for groups I and II and 75% for group III. Significant statistical differences were found between the 2 pyelotomy groups and the pyeloplasty group regarding the duration of the intervention. Significant statistical differences are evident in the evolution of the UPJ's diameter between groups I and III.

CONCLUSIONS

Laparoscopic pyeloplasty is the technique that produces fewer side effects in the reconstructed area, as well as a wider dilation of the UPJ. Nevertheless, as we show in this study, we found similar results between endopyelotomy in selected patients than pyeloplasty, and it is simpler and less invasive than the latter.

Application of Self-Expandable Metal Stents for Ureteroileal Anastomotic Strictures: Long-Term Results

PURPOSE

We report our long-term experience with the management of benign ureteroileal anastomotic strictures using self-expandable metal stents.

MATERIALS AND METHODS

A total of 16 male and 2 female patients with a mean+/-SD age of 72+/-7 years (range 66 to 78) with benign fibrotic strictures at the site of ureteroileal anastomosis underwent implantation of self-expandable metal stents with a nominal diameter of 6 to 8 mm. A total of 24 ureteroileal conduits were treated. The external nephrostomy tubes were removed after fluoroscopic validation of ureteral patency. Patients were followed with blood biochemistry, ultrasonography, urography and/or virtual endoscopy. Retrograde external-internal catheter insertion through the cutaneous stoma was performed in cases of recalcitrant stricture.

RESULTS

The technical success rate of ureteroileal stricture crossing and stenting was 100% (24 of 24 cases). Mean followup was 21 months (range 7 to 50). The clinical success rate during the immediate post-stenting period was 70.8% (17 of 24 cases). The 1 and 4-year primary patency rates were 37.8% and 22.7%, respectively. Secondary interventions included repeat balloon dilation in 15 ureters, of which 8 also underwent subsequent coaxial stent placement. The 1 and 4-year secondary patency rates were 64.8% and 56.7%, respectively. Except in 2 patients who died external-internal Double-J catheters continued to be inserted retrograde in 6 ureteroileal conduits. They are periodically exchanged to prevent mucous inspissation and stent encrustation.

CONCLUSIONS

Metal stents served as the definitive treatment for stricture in more than half of the cases, whereas in the remainder the stents allowed the uncomplicated and regular exchange of Double-J catheters in retrograde fashion. This combined, less invasive treatment for ureteroileal anastomotic strictures may help patients avoid surgical revision and preserve quality of life.