The Role of Routine Ureteral Stenting Following Uncomplicated Ureteroscopic Treatment for Upper Ureteral and Renal Stones: A Randomized Control Trial.

Purpose: Ureteral stenting following uncomplicated ureteroscopy (URS) is common practice. Several studies have proven the safety of omitting routine stent placement following distal ureteral stone treatment. However, there is a paucity of data regarding the utility of stent placement for proximal URS. We designed a prospective, randomized controlled trial to evaluate the role of ureteral stent placement following URS for proximal ureteral and renal stones. Methods: Seventy-two patients with proximal ureteral or renal stones measuring as much as 1.5 cm were prospectively randomized into stented (37) or unstented (35) groups. The surgeon was blinded to the treatment group until after stone treatment. Patients tracked postoperative pain medications and completed validated pain questionnaires on postoperative days 0, 3, 7, and 28. Stents were removed on postoperative day 7. Postoperative follow-up imaging was obtained at 4 weeks. Results: No statistical differences were observed between the two groups in terms of demographics or stone characteristics. The operative time was longer in the stented group (p < 0.03). Patients in the stented group had more irritative urinary symptoms (p < 0.0001) and pain (p < 0.0001), missed more days of work (p < 0.01), and used more narcotics (p < 0.0005) during the first week, but no differences were observed at 30 days. Emergency room visits and overall complication rates were similar between the two groups. Three nonstented patients required stent placement. Two stented patients required early stent removal. Urinary tract infections developed in three stented patients, but not in unstented patients. Postoperative imaging did not reveal any hydronephrosis in either group, and the total stone-free rate was 94%. Conclusions: For most patients undergoing uncomplicated ureteroscopic treatment for proximal ureteral and kidney stones, it may be safe to omit ureteral stents to potentially decrease urinary symptoms and pain while improving short-term quality of life. Further studies with larger patient cohorts may be warranted to confirm our results.

Duration of Ureteral Stenting Following Ureteroscopic Perforation in a Porcine Model.

Objectives: Ureteroscopic ureteral perforations have been reported in up to 6% of cases, with recent studies suggesting a decline to less than 2%. Ureteroscopic perforations are managed with prolonged ureteral stenting of up to 6 weeks based on historical data. We sought to evaluate the time of urothelial healing and duration of ureteral stenting following a ureteroscopic perforation in a porcine model. Materials and Methods: Part A: Ureteral perforation using a semirigid ureteroscope was performed in 37 ureters. The ureters were stented using 4.7F × 22 cm stents for 3, 7, 10, or 14 days, and retrograde pyelograms performed after stent removal. Injured ureteral segments were collected for histologic evaluation. Part B: 8 ureters had endoscopic perforation and stenting for 7 days and then survived for 4 weeks for evaluation of urinary extravasation or hydronephrosis and histologic evaluation. Results: Part A: At 3 days of ureteral stenting, there was urinary extravasation on retrograde pyelograms and gross defect in all ureters; average creatinine increased (1.55-1.75 mg/dL). Starting at 7 days, no evidence of gross urothelial defects or extravasation, and average creatinine was stable. Histologic evaluation revealed urothelial healing by 7 days with ongoing tissue healing. Granulation tissue predominated in early phase of healing. Part B: With only 7 days of ureteral stenting, no extravasation or hydronephrosis developed a month after stent removal. Conclusions: Following ureteroscopic ureteral perforation in a porcine model, the urothelium is functionally intact with 7 days of stenting. These results are sustained without complications for at least 4 weeks after stent removal. While further studies are warranted, these results challenge the current practice of maintaining ureteral stenting for several weeks following ureteral perforation during ureteroscopy.

Semi-rigid ureteroscope as a dilator in renal stone ureteroscopic treatment.

INTRODUCTION: To determine the efficacy and safety of using the semi-rigid ureteroscope as the only ureteral dilator for primary ureteroscopy (URS) in the treatment of renal stones. MATERIALS AND METHODS: A retrospective review of primary URS for renal stone disease was performed on consecutive patients treated by a single provider from 2013 to 2017. Utilizing wire placement under fluoroscopic guidance and direct visual ureteroscopic dilation with a semi-rigid ureteroscope, primary outcome was successful completion of stone treatment. In addition, perioperative safety was evaluated. RESULTS: A total of 126 consecutive cases of primary URS using the semi-rigid ureteroscope as the only ureteral dilator were attempted for renal stone treatment. The renal stones were treated in 124 (98.4%) patients without other forms of active ureteral dilation. Two (1.6%) patients required ureteral stent placement for passive dilation despite attempted other dilating techniques. No intraoperative ureteral perforations were identified. Postoperative radiographic follow up was available for 67% patients with a 91% stone free rate and no hydronephrosis or ureteral strictures were detected. CONCLUSION: Utilizing direct visual semi-rigid ureteroscopic dilation with a semi-ridged ureteroscope prior to flexible ureteroscopy leads to successful primary ureteroscopy for renal stone treatment in most patients. This technique is an effective, safe and possibly cost-effective method of obtaining ureteral access to facilitate primary URS for renal stone treatment.

Tumor enucleation vs sharp excision in minimally invasive partial nephrectomy: technical benefit without impact on functional or oncologic outcomes.

OBJECTIVE: To present the benefits and utility of tumor enucleation as an alternative technique to sharp excision during minimally invasive partial nephrectomy (MIPN). METHODS: We retrospectively compared enucleation and sharp excision during MIPN, with the aim of determining benefits and limitations of enucleation in this setting. RESULTS: Among 602 patients undergoing MIPN at our institution, 86 and 516 underwent enucleation and sharp excision, respectively, as determined by the surgeon. The nephrometry score was greater in the enucleation vs sharp excision group (mean, 6.7 vs 6.3), but all other preoperative parameters were similar. The mean ischemia and operative times were 4 and 32 minutes shorter in the enucleation group, respectively, likely owing to less frequent entry into renal sinus (21% vs 41%) and need for tumor bed suturing (41% vs 62%), compared with those in the sharp excision group. There was no association with blood loss, positive margins, urine leak, blood transfusion, major complications, renal function, recurrence, or survival. CONCLUSION: Enucleation appears to provide the benefits of reduced surgical entry into the renal sinus, less need for tumor bed suturing, and shorter operative time, without any impact on functional or oncologic outcomes. Given favorable preoperative radiography and intraoperative findings, enucleation is a useful technique for patients undergoing MIPN.

Histotripsy effects on the bladder trigone: functional and histologic consequences in the canine model.

BACKGROUND: Histotripsy is an extracorporeal therapeutic ultrasound (US) technology, where high-amplitude acoustic energy is applied to targeted tissue. Previous research has demonstrated the feasibility, safety, and effectiveness of histotripsy tissue homogenization and debulking of the prostate in the canine model. Before translating this technology for human use, it is prudent to examine the susceptibility of critical periprostatic structures to cavitation injury in the event of histotripsy mistargeting. In this study, we sought to characterize the tissue effects and biologic response of directly treating the bladder trigone with histotripsy. MATERIALS AND METHODS: In eight anesthetized canines, 750,000 histotripsy pulses were applied uniformly across a 2×1.5-cm area encompassing the bladder trigone and ureteral orifices. Prostate and bladder trigone were harvested immediately after treatment (2 subjects) or at 14 days (6 subjects). Flexible cystourethroscopy, US imaging, and creatinine levels were obtained at intervals until harvest, 14 days after treatment. In one control subject, harvested at 2 days, the same treatment algorithm was applied to the prostate. RESULTS: Transrectal US imaging revealed a cavitation bubble cloud on the surface of the bladder trigone and progressive development of tissue edema during treatment. Flexible cystourethroscopy immediately after treatment confirmed edema and erythema of the trigone. In the six subjects survived 2 weeks after treatment, one incidence of transient, self-limited ureteral obstruction was noted based on hydronephrosis and creatinine levels. At harvest, ureteral orifices were confirmed patent by passage of a guide wire. Histologic evaluation revealed hemorrhage acutely with mild localized fibrosis at 14 days. CONCLUSIONS: In this study, designed along the lines of a worst-case, destructive testing scenario, direct targeting of the bladder trigone with supratherapeutic histotripsy failed to induce significant tissue damage or clinical complication. These results are reassuring and will guide treatment strategy in upcoming human clinical trials of histotripsy treatment for benign prostatic hyperplasia.

Determination of renal hypothermic temperature adequacy for renoprotection during ischemia using renal interstitial glycerol concentrations in a porcine model.

OBJECTIVES: To determine the effect of renal cooling on interstitial glycerol concentration during renal ischemia. The rate of cellular release of glycerol into the interstitial fluid at various hypothermic temperatures during ischemia was used to assess adequacy for renoprotection at those temperatures. METHODS: Twenty-four renal units in 12 pigs underwent ischemia during measurement of renal interstitial fluid glycerol concentration. Kidneys were categorized into a body temperature control group or various hypothermic temperature groups (n = 4): 5°, 10°, 15°, 20°, and 25°. RESULTS: The glycerol concentration of all kidneys increased directly with ischemic time. The rate of increase in glycerol concentrations over ischemic time decreased sequentially as renal temperature decreased. The glycerol concentration of the kidneys cooled to 25°C during ischemia was significantly less (P = .03) relative to the glycerol levels obtained from the kidneys subjected to warm ischemia at 120 minutes. CONCLUSIONS: Renal hypothermia decreases the rate of cellular release of glycerol into the interstitial fluid. Hypothermia at 25°C doubles the time required for renal interstitial glycerol to accumulate to levels associated with irreparable renal function damage. Therefore, relatively warmer hypothermic temperatures may be sufficient to extend a significant renoprotective effect during ischemia.