Intrarenal pressures during flexible ureteroscopy: an insight into safer endourology.

OBJECTIVES: To assess intrarenal pressures (IRPs) and complication rates after flexible ureteroscopy (fURS), and to assess factors that contribute to raised IRPs and postoperative complications. PATIENTS AND METHODS: After informed consent patients underwent fURS under general anaesthesia. The transducer of a 0.3556 mm (0.014″) pressure guidewire was placed in the renal pelvis for live recording of IRPs. The fURS procedures were performed in a routine manner under antibiotic cover with the aim of dusting the calculus to completion. The operating surgeon was blinded to the live-recorded IRPs. RESULTS: A total of 40 fURS procedures were performed in 37 patients (26 male and 11 female). The mean age was 50.5 years. As a cohort, the mean of average IRPs was 34.8 mmHg and the mean of maximal IRPs was 128.8 mmHg. Pearson's correlation showed a significant inverse correlation between the mean IRP and age (r[38]: -0.391, P = 0.013). Three cases experienced postoperative deviations from uncomplicated recovery, with two being hypotensive and one case being both hypotensive and hypoxic. Three cases returned to the emergency department within 30 days of surgery, with two cases of flank pain and one case of urosepsis with positive urine cultures. The patient presenting with urosepsis had exhibited IRPs exceeding the mean. CONCLUSION: The IRPs changed significantly from normal baseline levels during routine fURS. The mean IRP during fURS correlates with patient age, but not with other factors. The IRP may be related to increased complication rates at fURS. Understanding factors that influence IRP will allow urologists to better manage this intraoperatively.

Perspectives on technology: to use or to reuse, that is the endoscopic question-a systematic review of single-use endoscopes.

OBJECTIVE: To compare clinical outcomes of single-use endoscopes with those of reusable endoscopes to better define their role within urology. METHODS: A systematic search of electronic databases was performed. All studies comparing the clinical outcomes of participants undergoing urological procedures with single-use endoscopes to those of participants treated with reusable endoscopes were included. Results are reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement. RESULTS: Twenty-one studies in 3943 participants were identified. Six different single-use flexible ureteroscopes and two different single-use flexible cystoscopes were assessed. There were no differences in mean postoperative infection rates (4.0% vs 4.4%; P = 0.87) or overall complication rates (11.5% vs 11.9%; P = 0.88) between single-use and reusable endoscopes. For patients undergoing flexible ureteroscopy there were no differences in operating time (mean difference -0.05 min; P = 0.96), length of hospital stay (LOS; mean difference 0.06 days; P = 0.18) or stone-free rate (SFR; 74% vs 74.3%; P = 0.54) between the single-use and reusable flexible ureteroscope groups. CONCLUSION: This study is the largest to compare the clinical outcomes of single-use endoscopes to those of reusable endoscopes within urology, and demonstrated no difference in LOS, complication rate or SFR, with a shorter operating time associated with single-use flexible cystoscope use. It also highlights that the cost efficiency and environmental impact of single-use endoscopes is largely dependent on the caseload and reprocessing facilities available within a given institution. Urologists can therefore feel confident that whether they choose to 'use' or to 'reuse' based on the financial and environmental implications, they can do so without negatively impacting patient outcomes.

The impact of kidney stone disease on quality of life in high-risk stone formers.

OBJECTIVE: To assess the impact of kidney stone disease (KSD) and its treatment on the health-related quality of life (HRQOL) of high-risk stone formers with hyperparathyroidism, renal tubular acidosis, malabsorptive disease, and medullary sponge kidney. PATIENTS AND METHODS: The Wisconsin Stone Quality of Life questionnaire was used to evaluate HRQOL in 3301 patients with a history of KSD from 16 institutions in North America between 2014 and 2020. Baseline characteristics and medical history were collected from patients, while active KSD was confirmed through radiological imaging. The high-risk group was compared to the remaining patients (control group) using the Wilcoxon rank-sum test. RESULTS: Of 1499 patients with active KSD included in the study, the high-risk group included 120 patients. The high-risk group had significantly lower HRQOL scores compared to the control group (P < 0.01). In the multivariable analyses, medullary sponge kidney disease and renal tubular acidosis were independent predictors of poorer HRQOL, while alkali therapy was an independent predictor of better HRQOL (all P < 0.01). CONCLUSIONS: Among patients with active KSD, high-risk stone formers had impaired HRQOL with medullary sponge kidney disease and renal tubular acidosis being independent predictors of poorer HRQOL. Clinicians should seek to identify these patients earlier as they would benefit from prompt treatment and prevention.

Comparison of holmium:yttrium-aluminium-garnet (YAG), thulium fiber laser, and pulsed thulium:YAG lasers on soft tissue: an ex vivo study.

OBJECTIVES: To assess laser-tissue interactions through ablation, coagulation, and carbonisation characteristics in a non-perfused porcine kidney model between three pulsed lasers: holmium (Ho): yttrium-aluminium-garnet (YAG), thulium fiber laser (TFL), and pulsed thulium (p-Tm):YAG. MATERIALS AND METHODS: A 150-W Ho:YAG, a 60-W TFL, and a 100-W p-Tm:YAG lasers were compared. The laser settings that can be set identically between the three lasers and be clinically relevant for prostate laser enucleation were identified and used on fresh, unfrozen porcine kidneys. Laser incisions were performed using stripped laser fibers of 365 and 550 µm, set at distances of 0 and 1 mm from the tissue surface at a constant speed of 2 mm/s. Histological analysis evaluated shape, depth, width of the incision, axial coagulation depth, and presence of carbonisation. RESULTS: Incision depths, widths, and coagulation zones were greater with Ho:YAG and p-Tm:YAG lasers than TFL. Although no carbonisation was found with the Ho:YAG and p-Tm:YAG lasers, it was common with TFL, especially at high frequencies. The shapes of the incisions and coagulation zones were more regular and homogeneous with the p-Tm:YAG laser and TFL than with Ho:YAG laser. Regardless of the laser used, short pulse durations resulted in deeper incisions than long pulse durations. Concerning the distance, we found that to be effective, TFL had to be used in contact with the tissue. Finally, 365-µm fibers resulted in deeper incisions, while 550-µm fibers led to wider incisions and larger coagulation zones. CONCLUSION: Histological analysis revealed greater tissue penetration with the p-Tm:YAG laser compared to the TFL, while remaining less than with Ho:YAG. Its coagulation properties seem interesting insofar as it provides homogeneous coagulation without carbonisation, while incisions remained uniform without tissue laceration. Thus, the p-Tm:YAG laser appears to be an effective alternative to Ho:YAG and TFL lasers in prostate surgery.

Aquablation versus HoLEP in patients with benign prostatic hyperplasia: a comparative prospective non-randomized study.

PURPOSE: The question of best surgical treatment for lower urinary tract symptoms (LUTS) due to benign prostate hyperplasia (BPH) remains controversial. We compared the outcomes of aquablation and holmium laser enucleation of the prostate ("HoLEP") in a prospective cohort. METHODS: Patients with BPH underwent aquablation or HoLEP according to their preference between June 2020 and April 2022. Prostate volume ("PV"), laboratory results, postvoid residual volume, uroflowmetry, IPSS, ICIQ-SF, MSHQ-EjD, EES and IIEF were evaluated preoperatively and at three, six and 12 months postoperatively. We also analyzed perioperative characteristics and complications via the Clavien Dindo ("CD") classification. RESULTS: We included 40 patients, 16 of whom underwent aquablation and 24 HoLEP. Mean age was 67 years (SD 7.4). Baseline characteristics were balanced across groups, except the HoLEP patients' larger PV. IPSS fell from 20.3 (SD 7.1) at baseline to 6.3 (SD 4.2) at 12 months (p < 0.001) without differences between aquablation and HoLEP. HoLEP was associated with shorter operation time (59.5 (SD 18.6) vs. 87.2 (SD 14.8) minutes, p < 0.001) and led to better PV reduction over all timepoints. At three months, aquablation's results were better regarding ejaculatory (p = 0.02, MSHQ-EjD) and continence function (p < 0.001, ICIQ-SF). Beyond three months, erectile, ejaculatory, continence function and LUTS reduction did not differ significantly between aquablation and HoLEP. CD ≥ grade 3b complications were noted in six patients in aquablation group while only one in HoLEP group (p = < 0.01). CONCLUSIONS: While aquablation revealed temporary benefits regarding ejaculation and continence at three months, HoLEP was superior concerning operation time, the safety profile and volumetric results.

Trends in the use of radiation protection and radiation exposure of European endourologists: a prospective trial from the EULIS-YAU Endourology Group.

INTRODUCTION: Due to the radiation exposure for the urology staff during endourology, our aim was to evaluate the trends of radiation protection in the operation room by endourologists from European centers and to estimate their annual radiation. METHODS: We conducted a multicenter study involving experienced endourologists from different European centers to evaluate whether the protection and threshold doses recommended by the International Commission on Radiation Protection (ICRP) were being followed. A 36-question survey was completed on the use of fluoroscopy and radiation protection. Annual prospective data from chest, extremities, and eye dosimeters were collected during a 4-year period (2017-2020). RESULTS: Ten endourologists participated. Most surgeons use lead aprons and thyroid shield (9/10 and 10/10), while leaded gloves and caps are rarely used (2/10 both). Six out of ten surgeons wear leaded glasses. There is widespread use of personal chest dosimeters under the apron (9/10), and only 5/10 use a wrist or ring dosimeter and 4 use an eye dosimeter. Two endourologists use the ALARA protocol. The use of ultrasound and fluoroscopy during PCNL puncture was reported by 8 surgeons. The mean number of PCNL and URS per year was 30.9 (SD 19.9) and 147 (SD 151.9). The mean chest radiation was 1.35 mSv per year and 0.007 mSv per procedure. Mean radiation exposure per year in the eyes and extremities was 1.63 and 11.5 mSv. CONCLUSIONS: Endourologists did not exceed the threshold doses for radiation exposure to the chest, extremities and lens. Furthermore, the ALARA protocol manages to reduce radiation exposure.

Advancements in stone classification: unveiling the beauty of urolithiasis.

PURPOSE: Urolithiasis has become increasingly prevalent, leading to higher disability-adjusted life years and deaths. Various stone classification systems have been developed to enhance the understanding of lithogenesis, aid urologists in treatment decisions, and predict recurrence risk. The aim of this manuscript is to provide an overview of different stone classification criteria. METHODS: Two authors conducted a review of literature on studies relating to the classification of urolithiasis. A narrative synthesis for analysis of the studies was used. RESULTS: Stones can be categorized based on anatomical position, size, medical imaging features, risk of recurrence, etiology, composition, and morphoconstitutional analysis. The first three mentioned offer a straightforward approach to stone classification, directly influencing treatment recommendations. With the routine use of CT imaging before treatment, precise details like anatomical location, stone dimensions, and Hounsfield Units can be easily determined, aiding treatment planning. In contrast, classifying stones based on risk of recurrence and etiology is more complex due to dependencies on multiple variables, including stone composition and morphology. A classification system based on morphoconstitutional analysis, which combines morphological stone appearance and chemical composition, has demonstrated its value. It allows for the rapid identification of crystalline phase principles, the detection of crystalline conversion processes, the determination of etiopathogenesis, the recognition of lithogenic processes, the assessment of crystal formation speed, related recurrence rates, and guidance for selecting appropriate treatment modalities. CONCLUSIONS: Recognizing that no single classification system can comprehensively cover all aspects, the integration of all classification approaches is essential for tailoring urolithiasis patient-specific management.

Radiation exposure of urologists during endourological procedures: a systematic review.

INTRODUCTION: Ionizing radiation is used daily during endourological procedures. Despite the dangers of both deterministic and stochastic effects of radiation, there is a lack of knowledge and awareness among urologists. This study reviewed the literature to identify the radiation exposure (RE) of urologists during endourological procedures. METHODS: A literature search of the Medline, Web of Science, and Google Scholar databases was conducted to collect articles related to the radiation dose to urologists during endourological procedures. A total of 1966 articles were screened. 21 publications met the inclusion criteria using the PRIMA standards. RESULTS: Twenty-one studies were included, of which 14 were prospective. There was a large variation in the mean RE to the urologist between studies. PCNL had the highest RE to the urologist, especially in the prone position. RE to the eyes and hands was highest in prone PCNL, compared to supine PCNL. Wearing a thyroid shield and lead apron resulted in a reduction of RE ranging between 94.1 and 100%. Educational courses about the possible dangers of radiation decreased RE and increased awareness among endourologists. CONCLUSIONS: This is the first systematic review in the literature analyzing RE to urologists over a time period of more than four decades. Wearing protective garments such as lead glasses, a thyroid shield, and a lead apron are essential to protect the urologist from radiation. Educational courses on radiation should be encouraged to further reduce RE and increase awareness on the harmful effects of radiation, as the awareness of endourologists is currently very low.

Radiation exposure of patients during endourological procedures.

PURPOSE: Considering the existing gaps in the literature regarding patient radiation dose (RD) and its associated risks, a systematic review of the literature on RD was conducted, focusing on percutaneous nephrolithotomy (PCNL), extracorporeal shock wave lithotripsy (SWL), and ureteroscopy (URS). METHODS: Two authors conducted a literature search on PubMed, Web of Science, and Google Scholar to identify studies on RD during endourological procedures. Two thousand two hundred sixty-six articles were screened. Sixty-five publications met the inclusion criteria using the PRISMA standards. RESULTS: RD was generally highest for PCNL, reaching levels up to 33 mSv, 28,700 mGycm2, and 430.8 mGy. This was followed by SWL, with RD reaching up to 7.32 mSv, 13,082 mGycm2, and 142 mGy. URS demonstrated lower RD, reaching up to 6.07 mSv, 8920 mGycm2, and 46.99 mGy. Surgeon experience and case load were inversely associated with RD. Strategies such as optimizing fluoroscopy settings, implementing ultrasound (US), and following the ALARA (As Low As Reasonably Achievable) principle minimized RD. CONCLUSIONS: This is the first systematic review analyzing RD, which was generally highest during PCNL, followed by SWL and URS. There is no specific RD limit for these procedures. Implementation of strategies such as optimizing fluoroscopy settings, utilizing US, and adhering to the ALARA principle proved effective in reducing RD. However, further research is needed to explore the factors influencing RD, assess their impact on patient outcomes, and establish procedure-specific reference levels for RD.

Patients undergoing double J substitution with a pigtail suture stent report a significant decrease of stent-related symptoms. Results from a prospective multicenter longitudinal trial.

PURPOSE: To compare stent-related symptoms (SRS) in patients with double J (DJ) undergoing substitution with a pigtail suture stent (PSS) after ureteroscopy (URS), through the Ureteral Stent Symptom Questionnaire (USSQ). MATERIALS AND METHODS: Patients with DJ undergoing URS for stone treatment were enrolled in this prospective multicenter longitudinal study. The USSQ was submitted thrice: 2 weeks after DJ, 2 weeks after PSS and 4 weeks after PSS removal (baseline). PRIMARY ENDPOINT: to compare Urinary Symptom Index Score and the rate of patients with pain 2 weeks after DJ and PSS. Secondary endpoints: to compare other USSQ scores and single answers 2 weeks after DJ and PSS, and DJ and PSS USSQ scores with baseline. RESULTS: 93 patients were enrolled. 2 weeks Urinary Symptom Index Score (p < 0.001) and the percentage of patients complaining of pain (60.2% vs 88.2%, p < 0.001) were significantly in favour of PSS compared to DJ. 2 weeks scores were significantly improved with PSS compared to DJ: Pain Index (p < 0.001), VAS (p < 0.001), General Health Index (p < 0.001) and Work Performance Index (p < 0.001). All urinary symptoms were significantly decreased with PSS, including renal pain during micturition and pain interfering with life. Pain Index Score (p = 0.622) and VAS (p = 0.169) were comparable to baseline with PSS, while differed with DJ. CONCLUSIONS: Patients undergoing DJ substitution with PSS after URS report a significant decrease of SRS. Urologists may consider positioning PSS after URS in pre-stented patients to reduce the impact of SRS.

Telemedicine in Endourology for Patient Management and Healthcare Delivery: Current Status and Future Perspectives.

PURPOSE OF REVIEW: Researchers have examined how telemedicine affects endourological patients. This review analyzes the literature to determine telemedicine's benefits and limitations in endourology. RECENT FINDINGS: Many studies were devoted to describing the effect of telemedicine on endourological patient satisfaction, optimization of the clinical decision-making among patients with kidney and ureteric stones, the effectiveness of telemedicine in the management of patients with indications for PCNL, follow-up for patients with urolithiasis and describing financial effectiveness for the patients after BOO surgery. The authors describe phone calls, video calls, and online booking platforms as used as telemedicine technology. However, several concerns also exist, such as the necessity of internet connections and appropriate devices, different receptivity among certain subgroups, data safety, and different regulatory environments among countries. Telemedicine offers the potential to reduce patient travel time, expedite decision-making, and save costs in endourology. However, its everyday implementation is challenging due to various obstacles faced by patients and providers, hindering the realization of its full potential and necessitating a systematic approach to problem-solving.

First 100 Reported Cases of Supine Percutaneous Nephrolithotomy in Malaysia: An Alternative Effective and Safe Approach to Treat Renal Stones.

Background: Supine percutaneous nephrolithotomy (s-PCNL) offers great benefits from urological and anaesthetic points of view. We present the first evaluation of the outcomes of s-PCNL in Malaysia. Our aim was to explore the safety and efficacy of s-PCNL. Methods: Institutional review board approval was obtained from the National Medical Research Register (NMRR ID-21002225-WLP). We retrospectively reviewed 115 patients with renal pelvis stones who underwent single renal access during s-PCNL between November 2020 and May 2023. Patients who underwent simultaneous ipsilateral or contralateral endourological procedures were included. The data were analysed to determine stone-free rates (SFR), major complication rates, blood transfusion rates, operative times and lengths of hospital stay (LOS). Results: The SFR was higher for the single middle calyceal renal access (MCA) group than for the lower calyceal renal access (LCA) or upper calyceal renal access (UCA) groups (OR: 1.76; 95% confidence interval [CI]: 0.63, 4.92). In total, 0, 1 and 2 patients had major complications in the UCA, MCA and LCA groups, respectively (P = 0.453). One of the 115 patients (0.9%) needed blood transfusion. Subgroup analysis revealed mean operative times of 76.3 min and 78.6 min for patients who underwent sole s-PCNL (PCNL-only group) and those who had simultaneous ipsilateral and contralateral endourological procedures (PCNL-plus group), respectively (P = 0.786). The overall mean LOS was 2.9 days. Conclusion: s-PCNL is a safe and effective alternative treatment for renal stones. We would recommend s-PCNL for patients who require an ipsilateral/contralateral endourological procedure (URS/RIRS) because it is time-efficient. All renal accesses are safe. Single MCA is recommended for complete stone clearance.

The Uniform grading tooL for flexIble ureterorenoscoPes (TULIP-tool): a Delphi consensus project on standardised evaluation of flexible ureterorenoscopes.

OBJECTIVE: To develop a standardised tool to evaluate flexible ureterorenoscopes (fURS). MATERIALS AND METHODS: A three-stage consensus building approach based on the modified Delphi technique was performed under guidance of a steering group. First, scope- and user-related parameters used to evaluate fURS were identified through a systematic scoping review. Then, the main categories and subcategories were defined, and the expert panel was selected. Finally, a two-step modified Delphi consensus project was conducted to firstly obtain consensus on the relevance and exact definition of each (sub)category necessary to evaluate fURS, and secondly on the evaluation method (setting, used tools and unit of outcome) of those (sub)categories. Consensus was reached at a predefined threshold of 80% high agreement. RESULTS: The panel consisted of 30 experts in the field of endourology. The first step of the modified Delphi consensus project consisted of two questionnaires with a response rate of 97% (n = 29) for both. Consensus was reached for the relevance and definition of six main categories and 12 subcategories. The second step consisted of three questionnaires (response rate of 90%, 97% and 100%, respectively). Consensus was reached on the method of measurement for all (sub)categories. CONCLUSION: This modified Delphi consensus project reached consensus on a standardised grading tool for the evaluation of fURS - The Uniform grading tooL for flexIble ureterorenoscoPes (TULIP) tool. This is a first step in creating uniformity in this field of research to facilitate future comparison of outcomes of the functionality and handling of fURS.

Upper urinary tract pressures in endourology: a systematic review of range, variables and implications.

OBJECTIVES: To systematically review the literature to ascertain the upper tract pressures generated during endourology, the relevant influencing variables and clinical implications. MATERIALS AND METHODS: A systematic review of the MEDLINE, Scopus and Cochrane databases was performed by two authors independently (S.C., N.D.). Studies reporting ureteric or intrarenal pressures (IRP) during semi-rigid ureteroscopy (URS)/flexible ureterorenoscopy (fURS)/percutaneous nephrolithotomy (PCNL)/miniaturized PCNL (mPCNL) in the period 1950-2021 were identified. Both in vitro and in vivo studies were considered for inclusion. Findings were independently screened for eligibility based on content, with disagreements resolved by author consensus. Data were assessed for bias and compiled based on predefined variables. RESULTS: Fifty-two studies met the inclusion criteria. Mean IRP appeared to frequently exceed a previously proposed threshold of 40 cmH2 O. Semi-rigid URS with low-pressure irrigation (gravity <1 m) resulted in a wide mean IRP range (lowest reported 6.9 cmH2 O, highest mean 149.5 ± 6.2 cmH2 O; animal models). The lowest mean observed with fURS without a ureteric access sheath (UAS) was 47.6 ± 4.1 cmH2 O, with the maximum peak IRP being 557.4 cmH2 O (in vivo human data). UAS placement significantly reduced IRP during fURS, but did not guarantee pressure control with hand-operated pump/syringe irrigation. Miniaturization of PCNL sheaths was associated with increased IRP; however, a wide mean human IRP range has been recorded with both mPCNL (lowest -6.8 ± 2.2 cmH2 O [suction sheath]; highest 41.2 ± 5.3 cmH2 O) and standard PCNL (lowest 6.5 cmH2 O; highest 41.2 cmH2 O). Use of continuous suction in mPCNL results in greater control of mean IRP, although short pressure peaks >40 cmH2 O are not entirely prevented. Definitive conclusions are limited by heterogeneity in study design and results. Postoperative pain and pyrexia may be correlated with increased IRP, however, few in vivo studies correlate clinical outcome with measured IRP. CONCLUSIONS: Intrarenal pressure generated during upper tract endoscopy often exceeds 40 cmH2 O. IRP is multifactorial in origin, with contributory variables discussed. Larger prospective human in vivo studies are required to further our understanding of IRP thresholds and clinical sequelae.

Infection after ureteroscopy for ureteric stones: analysis of 71 305 cases in the Hospital Episode Statistics database.

OBJECTIVES: To investigate the burden of infectious complications following ureteroscopy (URS) for ureteric stones on a national level in England using data from the Hospital Episodes Statistics (HES) data warehouse. MATERIALS AND METHODS: A retrospective cohort was identified and followed up in HES during the period April 2013 to March 2020 for all procedure codes relating to ureteroscopic stone treatment (M27.1, M27.2, M27.3). Treatment episodes relating to the first URS ('index ureteroscopy') for each patient were further analysed. All subsequent admissions within 30 days were also captured. The primary outcome was diagnosis of urinary tract infection (UTI; including all codes relating to a UTI/sepsis within the first 30 days of index URS). Secondary outcomes were critical care attendance, attendance at the accident and emergency department (A&E) within 30 days, and mortality. RESULTS: A total of 71 305 index ureteroscopies were eligible for analysis. The median age was 55 years, and 81% of procedures were elective and 45% were undertaken as day-cases. At the time of index URS, 16% of patients had diabetes, 0.5% had coexisting neurological disease and 40% had an existing stent/nephrostomy. Overall, 6.8% of the cohort (n = 4822) had a diagnosis of UTI within 30 days of index URS (3.9% immediately after surgery). A total of 339 patients (0.5%) required an unplanned stay in critical care during their index URS admission; 8833 patients (12%) attended A&E within 30 days. Overall mortality was 0.18% (60 in-hospital, 65 within 30 days); 40 deaths (0.056%) included infection as a contributing cause of death. CONCLUSION: We present the largest series evaluating infectious complications after ureteroscopic stone treatment. The procedure is safe, with low inpatient infective complication and critical care admission rates.

Evaluation of fluid absorption during flexible ureteroscopy in an in vivo porcine model.

OBJECTIVE: To evaluate the relationship between renal pelvis pressure and fluid absorption during ureteroscopy (URS) in a live porcine model. MATERIALS AND METHODS: Flexible URS (fURS) was performed in anaesthetised female Yorkshire pigs. Prior to performing fURS, a 0.3556-mm (0.014″) pressure-sensing guidewire (Comet™, Boston Scientific) was placed to monitor renal pelvis pressure. A simulated fURS procedure was then performed for 1 h. Infusion of irrigation fluid (5% ethanol in saline) at target renal pelvis pressures (37-150 mmHg) was maintained for 1 h using a pressure bag and real-time feedback from the pressure-sensing guidewire. Venous blood was sampled every 10 min. The volume of irrigation fluid absorbed was estimated with established equations. RESULTS: A URS procedure was performed in vivo in 18 porcine kidneys and the volume of irrigation fluid absorbed during the 1 h URS was calculated. The mean (SD) volume of irrigation fluid absorbed after 1 h of simulated URS was 7.6 (5.7), 10.8 (7.1), 26.0 (15.8), and 56.8 (22.3) mL at renal pelvis pressures of 37, 55, 75, and 150 mmHg, respectively. Compared with URS with renal pelvis pressure of 37 mmHg, the volume of fluid absorption was significantly greater at renal pelvis pressures of 75 and 150 mmHg (P = 0.026 and P = 0.047, respectively). In addition, compared with URS with renal pelvis pressure of 37 mmHg, the rate of absorption was significantly greater at renal pelvis pressures of 75 and 150 mmHg (both P < 0.001). CONCLUSION: In this study of an in vivo porcine model of URS, increasing renal pelvis pressures during URS were associated with increases in irrigation fluid absorption and increases in the rate of fluid absorption.

International Alliance of Urolithiasis guideline on retrograde intrarenal surgery.

OBJECTIVES: To set out the second in a series of guidelines on the treatment of urolithiasis by the International Alliance of Urolithiasis that concerns retrograde intrarenal surgery (RIRS), with the aim of providing a clinical framework for urologists performing RIRS. MATERIALS AND METHODS: After a comprehensive search of RIRS-related literature published between 1 January 1964 and 1 October 2021 from the PubMed database, systematic review and assessment were performed to inform a series of recommendations, which were graded using modified GRADE methodology. Additionally, quality of evidence was classified using a modification of the Oxford Centre for Evidence-Based Medicine Levels of Evidence system. Finally, related comments were provided. RESULTS: A total of 36 recommendations were developed and graded that covered the following topics: indications and contraindications; preoperative imaging; preoperative ureteric stenting; preoperative medications; peri-operative antibiotics; management of antithrombotic therapy; anaesthesia; patient positioning; equipment; lithotripsy; exit strategy; and complications. CONCLUSION: The series of recommendations regarding RIRS, along with the related commentary and supporting documentation, offered here should help provide safe and effective performance of RIRS.

In vivo ureteroscopic intrarenal pressures and clinical outcomes: a multi-institutional analysis of 120 consecutive patients.

OBJECTIVES: To evaluate the pressure range generated in the human renal collecting system during ureteroscopy (URS), in a large patient sample, and to investigate a relationship between intrarenal pressure (IRP) and outcome. PATIENTS AND METHODS: A prospective multi-institutional study was conducted, with ethics board approval; February 2022-March 2023. Recruitment was of 120 consecutive consenting adult patients undergoing semi-rigid URS and/or flexible ureterorenoscopy (FURS) for urolithiasis or diagnostic purposes. Retrograde, fluoroscopy-guided insertion of a 0.036-cm (0.014″) pressure guidewire (COMET™ II, Boston Scientific, Marlborough, MA, USA) to the renal pelvis was performed. Baseline and continuous ureteroscopic IRP was recorded, alongside relevant operative variables. A 30-day follow-up was completed. Descriptive statistics were applied to IRP traces, with mean (sd) and maximum values and variance reported. Relationships between IRP and technical variables, and IRP and clinical outcome were interrogated using the chi-square test and independent samples t-test. RESULTS: A total of 430 pressure traces were analysed from 120 patient episodes. The mean (sd) baseline IRP was 16.45 (5.99) mmHg and the intraoperative IRP varied by technique. The mean (sd) IRP during semi-rigid URS with gravity irrigation was 34.93 (11.66) mmHg. FURS resulted in variable IRP values: from a mean (sd) of 26.78 (5.84) mmHg (gravity irrigation; 12/14-F ureteric access sheath [UAS]) to 87.27 (66.85) mmHg (200 mmHg pressurised-bag irrigation; 11/13-F UAS). The highest single pressure peak was 334.2 mmHg, during retrograde pyelography. Six patients (5%) developed postoperative urosepsis; these patients had significantly higher IRPs during FURS (mean [sd] 81.7 [49.52] mmHg) than controls (38.53 [22.6] mmHg; P < 0.001). CONCLUSIONS: A dynamic IRP profile is observed during human in vivo URS, with IRP frequently exceeding expected thresholds. A relationship appears to exist between elevated IRP and postoperative urosepsis.

Effectiveness of endourological management of ureteral stenosis in kidney transplant patients: EAU-YAU kidney transplantation working group collaboration.

PURPOSE: Ureteral stenosis (US) in kidney transplant (KT) recipients is associated with poorer long-term graft survival. Surgical repair is the standard of care, and endoscopic treatment represents an alternative for stenosis < 3 cm. We aimed to determine the effectiveness and safety of endourological management of US in KT patients and predictors of failure. METHODS: A retrospective multicenter study was conducted in four European referral centers, including all KT patients with US managed endoscopically between 2009 and 2021. Clinical success was defined as the absence of upper urinary tract catheterization, surgical repair or transplantectomy during follow-up. RESULTS: A total of 44 patients were included. The median time to US onset was 3.5 months (IQR 1.9-10.8), the median length of stricture was 10 mm (IQR 7-20). Management of US involved balloon dilation and laser incision in 34 (79.1%) and 6 (13.9%) cases, respectively, while 2 (4.7%) received both. Clavien-Dindo complications were infrequent (10%); only one Clavien ≥ III complication was reported. Clinical success was 61% at last follow-up visit (median = 44.6 months). In the bivariate analysis, duckbill-shaped stenosis (vs. flat/concave) was associated with treatment success (RR = 0.39, p = 0.04, 95% CI 0.12-0.76), while late-onset stenosis (> 3 months post KT) with treatment failure (RR = 2.00, p = 0.02, 95% CI 1.01-3.95). CONCLUSIONS: Considering the acceptable long-term results and the safety of these procedures, we believe that the endoscopic treatment should be offered as a first-line therapy for selected KT patients with US. Those with a short and duckbill-shaped stenosis diagnosed within 3 months of KT seem to be the best candidates.

The heat is on: the impact of excessive temperature increments on complications of laser treatment for ureteral and renal stones.

OBJECTIVE: Technological advancements in the field of urology have led to a paradigm shift in the management of urolithiasis towards minimally invasive endourological interventions, namely ureteroscopy and percutaneous nephrolithotomy. However, concerns regarding the potential for thermal injury during laser lithotripsy have arisen, as studies have indicated that the threshold for cellular thermal injury (43 °C) can be exceeded, even with conventional low-power laser settings. This review aims to identify the factors that contribute to temperature increments during laser treatment using current laser systems and evaluate their impact on patient outcomes. MATERIALS AND METHODS: To select studies for inclusion, a search was performed on online databases including PubMed and Google Scholar. Keywords such as 'temperature' or 'heat' were combined with 'lithotripsy', 'nephrolithotomy', 'ureteroscopy', or 'retrograde intrarenal surgery', both individually and in various combinations. RESULTS: Various strategies have been proposed to mitigate temperature rise, such as reducing laser energy or frequency, shortening the duration of laser activation, increasing the irrigation fluid flow rate, and using room temperature or chilled water for irrigation. It is important to note that higher irrigation fluid flow rates should be approached cautiously due to potential increases in intrarenal pressure and associated infectious complications. The utilization of a ureteral access sheath (UAS) may offer benefits by facilitating irrigation fluid outflow, thereby reducing intrapelvic pressure and intrarenal fluid temperature. CONCLUSION: Achieving a balance between laser power, duration of laser activation, and irrigation fluid rate and temperature appears to be crucial for urologists to minimize excessive temperature rise.