Assessment of stone ablation rate using the Moses technology modes with different energy and pulse settings: An experimental study.

Objectives: To compare lithotripsy ablation rate with the Moses modes versus conventional pulse modes when using the Holmium:Yttrium-Aluminum-Garnet (Ho:YAG) laser. Methods: The Lumenis® Pulse P120H Holmium Laser System and a 365 µm Moses D/F/L fiber were used to assess stone ablation rate in conventional Short and Long Pulse as well as Moses Contact and Distance at 10 W (0.5Jx20Hz and 2Jx5Hz) and 60 W (1Jx60Hz and 2Jx30Hz). Hard and soft phantom stones were formed, and all tests were conducted in a custom experimental configuration installed in a saline-filled bath. The laser was delivered up to 3 kJ of total energy. The fragmentation pattern was assessed via photographs in each cohort. Results: The time to reach the target energy was 5 min and 50 s in all 10 W and 60 W trials, respectively. In both stone types, ablation was more effective when high-power, high-energy and Moses Distance was utilized. In soft stones, the lowest ablation rate was detected in the Long Pulse modality in all power, energy and frequency settings. Overall, when dusting settings (high-frequency, low-energy) were used, a deeper single cavitation was observed rather than small cavitations. Conclusions: The most effective pulse modality as evaluated via stone ablation rate depends on the stone hardness as well as energy and frequency settings. In both hard and soft stones, ablation is more effective when 60 W (2Jx30Hz) power settings and Moses Distance are used. Tailored laser settings in terms of energy and frequency could be set for each case scenario.

Outcomes of thulium prostatectomy with "Oyster technique" versus transurethral prostatectomy (TURP): a randomized control trial.

PURPOSE: To compare the perioperative and postoperative outcomes between Oyster prostate vaporesection using Tm-YAG laser and the conventional transurethral prostatectomy using monopolar energy. METHODS: Patients with LUTS with an accumulative size of at least 60 ml were randomly assigned to one of two parallel groups to undergo Tm-YAG laser vaporesection (Group 1) or conventional monopolar transurethral prostatectomy (Group 2). The primary endpoints were the reduction in IPSS and the increase in Qmax postoperatively. Secondary endpoints included the Hemoglobin drop, the complication rate, the changes in urodynamic parameters, the duration of hospitalization and catheterization and the changes in IIEF during the 24-month follow-up. RESULTS: In total 32 and 30 patients were enrolled in Groups 1 and 2, respectively. Patient age (p = 0.422) and prostate volume were similar among the groups (p = 0.51). The outcomes in terms of IPSS decrease and Qmax amelioration were comparable (p = 0.449 and p = 0.237, respectively). Operative and hospitalization times were lower in Group 1 (p = 0.002 and p = 0.004, respectively). Hemoglobin drop, changes in urodynamic parameters and improvement in IIEF and QoL scores did not differ among the two Groups. The average time with the catheter was 2.06 ± 0.35 and 2.5 ± 0.82 (p = 0.003) days for Group 1 and Group 2, respectively. The overall complication rate was 6.2% for Group 1 and 13.3% for Group 2. CONCLUSIONS: The Oyster technique leads to similar postoperative outcomes compared to the standard monopolar transurethral prostatectomy. The shorter catheterization, hospitalization and operation time should be considered advantages of the Oyster technique.

Holmium: Yttrium-aluminum-garnet laser lithotripsy: Is there a difference in ablation rates between short and long pulse duration?

Introduction: The high-power holmium: yttrium-aluminum-garnet lasers provide a wide variety of settings for stone disintegration. The aim of this in vitro study is to evaluate the effect of short and long pulse duration on ablation rates on urinary stones. Materials and Methods: Two types of artificial stones were created by BegoStone™ with different compositions (15:3 and 15:6, stone/water ratio). Stones with a 15:3 and 15:6 powder-to-water ratio were defined as hard and soft stones, respectively. Lithotripsy was performed with different laser settings using a custom-made in vitro model consisting of a 60 cm long and 19 mm diameter tube. The ablation rate is defined as the final total mass subtracted from the initial total mass and divided to the time of treatment. Stone ablation rates were measured according to different laser settings with total power of 10W (0,5J-20 Hz, 1J-10 Hz, 2J-5 Hz) and 60W (1J-60 Hz, 1,5J-40 Hz, 2J-30 Hz). Results: Higher pulse rates and higher total power settings were related to higher ablation rates. Short pulse duration was more effective on soft stones, whereas long pulse duration was more effective on hard stones. For the same power settings, the highest energy-lowest frequency combination resulted in higher ablation rate in comparison to the lowest energy-higher frequency combination. Finally, short and long pulse average ablation rates do not differ so much. Conclusion: Regardless of the stone type and pulse duration, utilization of higher power settings with higher energies increased the ablation rates. Higher ablation rates were demonstrated for hard stones using long pulse duration, and for soft stones with short pulse duration.

Effects of irrigation parameters and access sheath size on the intra-renal temperature during flexible ureteroscopy with a high-power laser.

OBJECTIVES: To investigate the effect of different laser power settings on intra-renal temperature (IRT) under different irrigation conditions during flexible ureteroscopy (FURS) in a live-anesthetized porcine model. METHODS: Following ethics approval, 2 female pigs weighing ~ 28 kg were used. Under general anesthesia, a percutaneous access was obtained to fix a K-type thermocouple inside the pelvi-calyceal system for real-time recording of IRT during FURS without UAS, UAS-10/12, UAS-12/14, and UAS-14/16F. A high-power holmium laser was used and the IRT was recorded during laser activation for up to 60 s at a laser power of 20 W, 40 W, and 60 W under gravity irrigation and manual pump irrigation. RESULTS: Under gravity irrigation, FURS without UAS was associated with hazardous IRT at a laser power as low as 20 W for as short as 20 s of laser activation. The IRT was rendered borderline when UAS was used. This UAS buffering effect disappeared with the use of higher laser-power settings (40 W and 60 W) with the maximal IRT exceeding 60 °C. Moreover, laser activation at 60 W was associated with very rapid increase in IRT within few seconds. Under pump irrigation, laser activation at the highest power setting (60 W) for 60 s was associated with a safe IRT, even without the use of UAS. The maximal IRT was below 45 °C. CONCLUSION: The use of high-power Ho:YAG laser carries potentially harmful thermal effect when used under gravity irrigation, even when large-diameter UAS is used. High-power settings (> 40 W) require high irrigation flow. The use of UAS is advisable to reduce the IRT and balance any intra-renal pressure increase.

The hemodynamic interactions of combination therapy with α-blockers and phosphodiesterase-5 inhibitors compared to monotherapy with α-blockers: a systematic review and meta-analysis.

OBJECTIVE: The present study systematically reviewed the safety of combined treatment with an alpha blocker and phosphodiesterase-5 inhibitor. MATERIALS AND METHODS: The study was performed according to the PRISMA statement. The included studies were randomized controlled trials that included at least one group on alpha-blocker monotherapy and one group on a combined treatment with an alpha blocker and phosphodiesterase-5 inhibitor. The primary endpoints were the hemodynamic effects of the two groups, specifically the clinically significant changes and a positive orthostatic test. The secondary endpoints were the adverse events of the two treatment modalities. RESULTS: A total of 6687 studies were screened, and 19 randomized controlled trials were eligible for the meta-analysis. The combined treatment more often produced a clinically significant hemodynamic change with an MD of 4.73 (CI 1.25, 17.94; I2 = 0%; p = 0.02), but the positive orthostatic test was similar between the groups with an MD of 1.64 (CI 0.36, 7.47; I2 = 50%; p = 0.52). The meta-analysis of adverse events favored alpha-blocker monotherapy with an OD of 0.5 (CI 0.32, 0.78; I2 = 44%; p = 0.002). However, if we consider only the adverse events due to hypotension, the result was similar between the two groups with an OD of 0.97 (CI 0.58, 1.64; I2 = 0%; p = 0.92). CONCLUSION: The combined treatment may produce a clinically significant hemodynamic change. The combination of alpha blocker and phosphodiesterase-5 inhibitor was safe because it did not increase the rate of adverse events due to hypotension.

Systematic Review and Meta-Analysis Comparing Percutaneous Nephrolithotomy, Retrograde Intrarenal Surgery and Shock Wave Lithotripsy for Lower Pole Renal Stones Less Than 2 cm in Maximum Diameter.

PURPOSE: The aim of the current systematic review and meta-analysis is to provide an answer on which is the most appropriate approach for the management of the lower pole stones with a maximal dimension of 2 cm or less. MATERIALS AND METHODS: A systematic review was conducted on PubMed®, SCOPUS®, Cochrane and EMBASE®. The PRISMA guidelines and the recommendations of the EAU Guidelines office were followed. Retrograde intrarenal surgery, shock wave lithotripsy and percutaneous nephrolithotomy were considered for comparison. The primary end point was the stone-free rate. RESULTS: A total of 15 randomized controlled trials were eligible. Percutaneous nephrolithotripsy and retrograde intrarenal surgery have higher stone-free rates in comparison to shock wave lithotripsy and require fewer re-treatment sessions. Operative time and complications seem to favor shock wave lithotripsy in comparison to percutaneous nephrolithotripsy, but this takes place at the expense of multiple shock wave lithotripsy sessions. Retrograde intrarenal surgery seems to be the most efficient approach for the management of stones up to 1 cm in the lower pole. CONCLUSIONS: The pooled analysis of the eligible studies showed that the management of lower pole stones should probably be percutaneous nephrolithotripsy or retrograde intrarenal surgery to achieve stone-free status over a short period and minimal number of sessions. For stones smaller than 10 mm, retrograde intrarenal surgery is more efficient in comparison to shock wave lithotripsy. The decision between the 2 approaches (percutaneous nephrolithotripsy or retrograde intrarenal surgery) should be individual, based on the anatomical parameters, the comorbidity and the preferences of each patient.

Combination Therapy with Alpha-blocker and Phosphodiesterase-5 Inhibitor for Improving Lower Urinary Tract Symptoms and Erectile Dysfunction in Comparison with Monotherapy: A Systematic Review and Meta-analysis.

CONTEXT: The effects of combination therapy consisted of an α-blocker and a phosphodiesterase-5 inhibitor (PDE5I) for the treatment of lower urinary tract symptoms (LUTS) and erectile dysfunction (ED). OBJECTIVE: To systematically investigate the efficacy and safety of combination therapy in comparison with monotherapy. EVIDENCE ACQUISITION: The study complied with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement and the recommendations of the European Association of Urology Guidelines office. The study was registered in the PROSPERO database with ID CRD42018086619. Only comparative prospective studies, randomized or quasirandomized, with at least one control group with monotherapy were selected for the meta-analysis. The primary endpoint was the quality of life related to LUTS and ED, measured with the International Prostate System Score (IPSS), maximum flow rate (Qmax), postvoid residual (PVR), and International Index of Erectile Function (IIEF). Secondary endpoints included the adverse events rate. In the subgroup analysis of the influence of adding a PDE5I to the treatment of LUTS, the use of different PDE5Is was considered. EVIDENCE SYNTHESIS: After the screening of 6687 publications, 25 randomized controlled trials were considered eligible to be included in the meta-analysis. In the combination group, IPSS was lower and Qmax was higher than in the α-blocker group, with mean differences (MDs) of 1.41 (95% confidence interval [CI]: 0.42, 2.41; I2 = 71%, p = 0.005) and -1.01 ml/s (95% CI: -1.58, -0.43; I2 = 58%, p = 0.0006), respectively. The mean change of the IPSS was bigger in the combination group, with an MD of -1.72 (95% CI: -2.55, -0.89; I2 = 37%, p < 0.0001). The mean change of Qmax was insignificant, with an MD of -0.61 (95% CI: -1.57, 0.34; I2 = 63%, p = 0.21), as well as PVR and the mean change of PVR, with MDs of 0.65 (95% CI: -5.37, 6.66; I2 = 76%, p = 0.83) and -20.79 (95% CI: -48.94, 7.37; I2 = 75%, p = 0.15), respectively. The IIEF and the mean change of the IIEF had no difference between the combination group and the PDE5I-monotherapy group, with MDs of 1.82 (95% CI: -0.91, 4.54; I2 = 40%, p = 0.19) and 0.25 (95% CI: -1.11, 1.62; I2 = 47%, p = 0.72), respectively. Regarding the adverse events, the meta-analysis was in favor of monotherapy. None of the studies reported any serious or severe adverse event. CONCLUSIONS: Treatment with combination therapy is more effective for the improvement of the IPSS. Less significant improvement was shown in Qmax. The beneficial effect of combination therapy regarding ED remains equivocal. The combination therapy seemed to be safe and well tolerated. PATIENT SUMMARY: In this study, we review the effects of the combination therapy consisting of an α-blocker and a phosphodiesterase-5 inhibitor for the treatment of lower urinary tract symptoms (LUTS) and erectile dysfunction (ED). We found strong evidence to suggest the combination therapy for the improvement of LUTS. Benefits regarding the treatment of ED are less clear.

The Effect of Irrigation Power and Ureteral Access Sheath Diameter on the Maximal Intra-Pelvic Pressure During Ureteroscopy: In Vivo Experimental Study in a Live Anesthetized Pig.

Objectives: To assess the effect of irrigation settings and the size of ureteral access sheath (UAS) on the maximal intra-pelvic pressure (IPPmax) during ureteroscopy (URS) in pigs. Materials and Methods: In supine position, three anesthetized female pigs underwent cystoscopy to insert a 6F ureteral catheter in each ureter. Pigs were then turned to prone position to establish a percutaneous access, insert a 10F nephrostomy tube in the kidney, and connect it to a urodynamic device. An 8F semi-rigid ureteroscope or the Flex-X2 Flexible Ureteroscope was used with two irrigation settings: gravity flow and manual pumping using a commercial pump. URS was performed without UAS and with the UAS 9.5/11, 12/14, 14/16 at the ureteropelvic junction and the IPPmax was recorded. Results: Under gravity irrigation, the recorded IPPmax during semi-rigid URS in the distal ureter and the renal pelvis was 0 and 30 cmH2O, respectively. Further, the IPPmax during flexible URS in the renal pelvis without UAS, with UAS 9.5/11.5, with UAS 12/14, and with UAS 14/16 was 23, 6, 2, and 1 cmH2O, respectively. Under manual pumping, the IPPmax during semi-rigid URS in the distal ureter and the renal pelvis was 84 and 105 cmH2O, respectively. Further, the IPPmax during flexible URS in the renal pelvis without UAS, with UAS 9.5/11.5, with UAS 12/14, and with UAS 14/16 was 45, 46, 18, and 1 cmH2O, respectively. Conclusion: Manual pumping can significantly increase the IPPmax to unsafe levels during URS. The UAS can significantly decrease the IPPmax, even under manual pumping. The larger the UAS, the lower the IPPmax. The use of UAS can render URS safer by acting as a safeguard against the consequences of increased IPP, even under forced irrigation.

Experimental Studies of Nonabsorbable Polymeric Surgical Clips for Use in Urologic Laparoscopy.

Objective: This study aimed to compare the stability of the Click'aV® (Grena®), Click'aV plus (Grena), and Hem-o-lok® (Weck®, Teleflex®) polymer clips and the evaluation of the clips stability on a complete porcine artery. Materials and Methods: A dynamometer with a custom support and clamp unit was used. The crank gradually increased the tension force being applied on the clip via the suture. Different directions for the application of the force were tested. The highest force before the start of slipping the suture was noted. The procedure was repeated three times for each ligating clip. Results: For transverse stability, the "XL-size" Grena Click'aV Plus required preventing slippage at a greater force compared to the Hem-o-lok (p = 0.0071). No significant differences found statistically between the Grena Click'aV and Hem-o-lok clips (p = 0.1). For longitudinal stability, the Hem-o-lok required a significantly higher force to be opened compared to the Click'aV (p = 0.0036), but no statistically significant difference was found compared to the Click'aV Plus (p = 0.1). Concerning porcine artery stability, the artery slipped through the Click'aV clip in both measurements at a force of 10.2 and 9.4 N. In contrast, the arteries were cut in all measurements using the Click'aV Plus and the Hem-o-lok clips at forces of 11.8 and 12.8 N and 12.9 and 14.2 N, respectively. None of the clips leaked with up to 300 mm Hg of intra-arterial pressure applied to porcine renal arteries. Conclusions: The Grena Click'aV Plus clip has similar performance to the Hem-o-lok clip, and this clip can be equally useful for ligating vessels in laparoscopic urologic surgeries. We believe, from our findings in this study as well as those from other reports, that vascular clips applied properly by experienced surgeons provide a safe, reliable, and considerable cost-saving option for vascular control in urologic laparoscopic surgery.

The use of S-curved coaxial dilator for urethral dilatation: Experience of a tertiary department.

OBJECTIVE: Urethral strictures can be treated by urethral dilation, optical internal urethrotomy, or open surgical reconstruction (urethroplasty). Urethral dilation is done with filiforms and followers, balloons, or coaxial dilators inserted over a guidewire. The S-curved coaxial dilator (SCCD) was designed to facilitate the passage of the dilator through the stricture and the urethra because it imitates the curved anatomy of the male urethra. This study presents our experience with SCCD. MATERIALS AND METHODS: We used this kind of dilation in 310 patients. The technique included the insertion of a hydrophilic floppy-tipped guidewire through the urethra directly into the bladder under fluoroscopic control. The SCCDs were then inserted over the guidewire. Dilators of gradually increased size from 8F to 20F were used. The follow-up of the patients includes uroflowmetry and measurement of postvoid residual at 4 weeks, 6 months, or in the case of a recurrence of symptoms. RESULTS: The age of the patients were 69.08 ± 15.77 years. The causes of urethral stricture were iatrogenic (n = 114), traumatic (n = 35), infectious (n = 22), and of unknown origin (n = 139). The stricture length was 1.62 ± 0.85 cm. The mean number of dilations needed per case was 2 (range: 1-15), and the time between the dilations was 212.19 ± 253.9 days. We had seven failures. CONCLUSION: We propose the S-curved coaxial dilators for urethral dilation as a safe and effective technique because of their similarity to the shape of the male urethra and because of their hydrophilic coating.

Robot-Assisted Simple Prostatectomy by an Extraperitoneal Approach.

The incidence of symptomatic benign prostate hyperplasia and bladder outlet obstruction has increased during the last two decades. Most of men are treated conservatively. When medical therapy is inadequate to relief symptoms, surgical treatment is necessary. Absolute indications for surgical treatment are gross hematuria, recurrent urinary infections and retentions as well as bladder stones. With advent of minimally invasive surgery, large prostates tend to be treated either endoscopically or laparoscopically (including robotic assistance). Herein, the robotic-assisted simple prostatectomy is described.

The effectiveness of ureteric metal stents in malignant ureteric obstructions: A systematic review.

OBJECTIVE: To review the literature on the effectiveness, safety and long-term patency of ureteric metal mesh stents (MSs), as a variety of MSs have been used for managing malignant ureteric obstruction over the last three decades. MATERIALS AND METHODS: A systematic review using the search string; Ureter∗ AND (stent OR endoprosthesis) AND metal∗ was conducted on PubMed, Scopus, Web of science and Cochrane Library online databases in May 2016. Prospective, retrospective, and comparative studies including MSs were included. The primary endpoint was the patency rate and the secondary endpoint was complications. RESULTS: In all, 324 publications were screened and 31 articles were included in the systematic review; 21 prospective and 10 retrospective studies. These studies reported the effectiveness of specific MSs in population studies, in comparative studies among different MSs, as well as among MSs and JJ stents. It should be noted that all comparative studies were retrospective. CONCLUSION: The experiences with vascular MSs, such as the Wallstent™ (Boston Scientific/Microvasive, Natick, MA, USA), were related to high occlusion rates, due to endoluminal hyperplasia, and long-term disappointing patency. The use of covered MSs designed for the vascular system was also unfavourable. The Memokath 051™ (PNN Medical A/S, Kvistgaard, Denmark) had better patency rates, but also higher migration rates. The long-term results were acceptable and rendered the Memokath 051 as a viable option for the management of malignant ureteric obstruction. The Uventa™ (Taewoong Medical, Seoul, Korea) and Allium™ (Allium Medical Solutions Ltd, Caesarea, Israel) MSs, specifically designed for ureteric placement, provided promising results. Nevertheless, the wide acceptance of these MSs would require well-designed clinical studies and long-term follow-up.

Minimally Invasive Surgical Ureterolithotomy Versus Ureteroscopic Lithotripsy for Large Ureteric Stones: A Systematic Review and Meta-analysis of the Literature.

CONTEXT: The management of large ureteric stones represents a technical and clinical challenge. OBJECTIVE: To investigate the safety and efficacy of minimally invasive surgical ureterolithotomy (MISU) in comparison with ureteroscopic lithotripsy (URS) for the treatment of large ureteric stones. EVIDENCE ACQUISITION: The Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) guidelines were followed for the conduction of the study, which was registered in the PROSPERO database. Search string was "(laparoscop* OR retroperito* OR robot*) AND ureterolitho*"; database scope included PubMed, SCOPUS, Cochrane, and EMBASE. Primary end points were the stone-free (SFR) and complications rates. Secondary end points included operative time and hospital stay. Subgroup analyses were performed for stones 1-2 and >2cm, as well as different lithotripters and ureteroscopes. Meta-analysis and forest-plot diagrams were performed with the RevMan 5.3.5 software. EVIDENCE SYNTHESIS: After screening 673 publications, seven randomized controlled trials were eligible to be included in the meta-analysis. A total of 778 patients were pooled after the elimination of the dropouts. No robotic cohorts were found. Only upper ureteral stones were treated in the included studies. The SFR at discharge and 3 mo was higher with MISU with odds ratios of 6.30 (95% confidence interval [CI]: 3.05, 13.01; I2=0%) and 5.34 (95% CI: 2.41, 8.81; I2=0%), respectively. The most common complications for MISU and URS were conversion to open surgery and stone migration to the renal pelvis, respectively. Favorable results in terms of operative time were observed in the case of URS with a mean difference of 29.5min (95% CI: 14.74, 44.26; I2=98%). Hospitalization time was favorable in the case of URS with a mean difference of 2.08 days (95% CI: 0.96, 3.20; I2=99%). CONCLUSIONS: This meta-analysis showed a significantly higher SFR at discharge and 3 mo for MISU in comparison with URS when upper ureteral stones were treated. Operative and hospitalization time favored URS over MISU. PATIENT SUMMARY: The current study investigated the literature on the minimally invasive management of large ureteric stones. The available evidence shows that both ureteroscopic lithotripsy and minimally invasive surgical ureterolithotomy could be considered for the treatment of these stones with similar results. The selection of the approach should be based on the advantages and disadvantages of each technique.

Drug eluting stent in urology / Estents ureterales liberadores de fármacos en urología

The Drug eluting stents (DESs) are the most commonly used stents in interventional cardiology. DESs have been shown to minimize the restenosis rate after stenting the coronary vessels by addressing the phenomena of smooth muscle proliferation and inflammation. The effect of the DESs is attributed to the antiproliferative drugs which are coated onto the stent and are released in controlled fashion. The anti-proliferative drugs reduce the hyperplastic reaction by inhibiting the smooth muscle cell cycle and their proliferation. Urological stents are important instruments of the everyday urological practice with a variety of indications for their use. Nevertheless, their use is hampered by a number of complications such as infection, patient discomfort, encrustation, migration and hyperplastic reaction. In an attempt to reduce the complications, the concept of DESs was introduced to Urology. DESs for ureteral or urethral as well as polymeric or metal have been evaluated in experimental studies. The clinical evaluation of DESs is limited only to polymeric stent with results that require further investigation and confirmation. The development of stent designed for the urinary tract, the selection of the appropriate substances combined with the appropriate experimental and clinical investigation would provide DESs acceptable for the urological practice

Los estents ureterales liberadores de fármacos (EULF) son los estents más utilizados en cardiología intervencionista. Han demostrado que minimizan la tasa de reestenosis después de su colocación en los vasos coronarios resolviendo el fenómeno de proliferación del músculo liso e inflamación. El efecto de los EULF se atribuye a los fármacos antiproliferativos que recubren el estent y se liberan de una forma controlada. Los fármacos antiproliferativos reducen la reacción hiperplásica por inhibición del ciclo celular del musculo liso y su proliferación. Los estents urológicos son instrumentos importantes en la práctica urológica diaria con una variedad de indicaciones para su uso. Sin embargo, su utilización se ve dificultada por complicaciones cómo la infección, la incomodidad del paciente, la incrustación, la migración y la reacción hiperplásica. El concepto de estent liberador de fármaco se introdujo en Urología en un intento por reducir las complicaciones. Los estents liberadores de fármacos para uréter o uretra, tanto poliméricos como metálicos se han evaluado en estudios experimentales. La evaluación clínica de los estents liberadores de fármacos se ha limitado sólo a los poliméricos, con resultados que requieren mayor investigación y confirmación. El desarrollo de estents diseñados para el tracto urinario, la selección de las substancias adecuadas, combinadas con la investigación experimental y clínica apropiada ofrecerá estents liberadores de fármacos aceptables para la práctica urológica