What is the definition of stone dust and how does it compare with clinically insignificant residual fragments? A comprehensive review.

PURPOSE: During endoscopic stone surgery, Holmium:YAG (Ho:YAG) and Thulium Fiber Laser (TFL) technologies allow to pulverize urinary stones into fine particles, ie DUST. Yet, currently there is no consensus on the exact definition of DUST. This review aimed to define stone DUST and Clinically Insignificant Residual Fragments (CIRF). METHODS: Embase, MEDLINE (PubMed) and Cochrane databases were searched for both in vitro and in vivo articles relating to DUST and CIRF definitions, in November 2023, using keyword combinations: "dust", "stones", "urinary calculi", "urolithiasis", "residual fragments", "dusting", "fragments", "lasers" and "clinical insignificant residual fragments". RESULTS: DUST relates to the fine pulverization of urinary stones, defined in vitro as particles spontaneously floating with a sedimentation duration ≥ 2 sec and suited for aspiration through a 3.6Fr-working channel (WC) of a flexible ureteroscope (FURS). Generally, an upper size limit of 250 µm seems to agree with the definition of DUST. Ho:YAG with and without "Moses Technology", TFL and the recent pulsed-Thulium:YAG (pTm:YAG) can produce DUST, but no perioperative technology can currently measure DUST size. The TFL and pTm:YAG achieve better dusting compared to Ho:YAG. CIRF relates to residual fragments (RF) that are not associated with imminent stone-related events: loin pain, acute renal colic, medical or interventional retreatment. CIRF size definition has decreased from older studies based on Shock Wave Lithotripsy (SWL) (≤ 4 mm) to more recent studies based on FURS (≤ 2 mm) and Percutaneous Nephrolithotomy(PCNL) (≤ 4 mm). RF ≤ 2 mm are associated with lower stone recurrence, regrowth and clinical events rates. While CIRF should be evaluated postoperatively using Non-Contrast Computed Tomography(NCCT), there is no consensus on the best diagnostic modality to assess the presence and quantity of DUST. CONCLUSION: DUST and CIRF refer to independent entities. DUST is defined in vitro by a stone particle size criteria of 250 µm, translating clinically as particles able to be fully aspirated through a 3.6Fr-WC without blockage. CIRF relates to ≤ 2 RF on postoperative NCCT.

Sepsis prevalence and associated hospital admission and mortality after ureteroscopy in employed adults.

OBJECTIVE: To determine 30-day inpatient mortality, intensive care unit (ICU) admissions, inpatient admissions/readmissions, and yearly trends in sepsis prevalence and inpatient mortality after ureteroscopy (URS) in employed adults. MATERIALS AND METHODS: We performed a retrospective analysis of the IBM MarketScan Commercial Database to identify employed adults aged 18-64 years who underwent URS between 2015 and 2019. Patients were categorized as having no sepsis (controls), non-severe sepsis, or severe sepsis within 30 days of URS. The main outcomes included inpatient mortality, ICU admissions, inpatient admissions, readmissions, and annual rates of sepsis and associated inpatient mortality. RESULTS: Among 109 496 patients undergoing URS, 5.6% developed sepsis (4.1% non-severe, 1.5% severe). The 30-day inpatient mortality rates were 0.03%, 0.3% and 2.5% for controls, non-severe sepsis and severe sepsis, respectively (P < 0.001). In a multivariable analysis, diagnosis of sepsis regardless of severity (hazard ratio [HR] 17.2, 95% confidence interval [CI] 10.5-28.1; P < 0.001) or severe sepsis (HR 49.5, 95% CI 28.9-84.7; P < 0.001) increased the risk of 30-day inpatient mortality compared to no sepsis (controls). ICU admissions on the day of procedure (1.5%, 19.8% and 52.4%), inpatient admission rates (18.3%, 74.9% and 76.9%) and readmission rates (7.1%, 12.0% and 15.9%) were higher with severe sepsis and non-severe sepsis vs controls (all P < 0.001). During the study period, the prevalence of sepsis after URS increased from 4.7% to 6.6% (P < 0.001), while the associated mortality rate decreased from 0.7% to 0.2% (P < 0.001). CONCLUSION: Among working adults aged 18-64 years, sepsis after URS increases the risk of 30-day inpatient mortality, ICU and hospital admission, and hospital readmission. Although the prevalence of sepsis after URS is increasing over time, associated mortality rates are declining. Urologists should be aware of the potentially deadly consequences of sepsis after URS in younger patients.

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.

Supine versus Prone Percutaneous Nephrolithotomy for Complex Stones: A Multicenter Randomized Controlled Trial.

PURPOSE: High-quality evidence comparing supine to prone percutaneous nephrolithotomy (PCNL) for the treatment of complex stones is lacking. This study aimed to compare the outcomes of supine position (SUP) and prone position (PRO) PCNL. MATERIALS AND METHODS: A noninferior randomized controlled trial was performed according to the CONSORT (Consolidated Standards for Reporting Trials) criteria. The inclusion criteria were patients over 18 years of age with complex stones. SUP was performed in the Barts flank-free modified position. Except for positioning, all the surgical parameters were identical. The primary outcome was the difference in the success rate on the first postoperative day (POD1) between groups. The secondary outcome was the difference in the stone-free rate (SFR) on the 90th postoperative day (final SFR). A noninferiority margin of 15% was used. Demographic, operative, and safety variables were compared between the groups. Statistical significance was set at p <0.05. RESULTS: Overall, 112 patients were randomized and their demographic characteristics were comparable. The success rates on POD1 were similar (SUP: 62.5% vs PRO: 57.1%, p=0.563). The difference observed (-5.4%) was lower than the predefined limit. The final SFRs were also similar (SUP: 55.4% vs PRO: 50.0%, p=0.571). SUP had a shorter operative time (mean±SD 117.9±39.1 minutes vs 147.6±38.8 minutes, p <0.001) and PRO had a higher rate of Clavien ≥3 complications (14.3% vs 3.6%, p=0.045). CONCLUSIONS: Positioning during PCNL for complex kidney stones did not impact the success rates; consequently, both positions may be suitable. However, SUP might be associated with a lower high-grade complication rate.

Tranexamic acid in patients with complex stones undergoing percutaneous nephrolithotomy: a randomised, double-blinded, placebo-controlled trial.

OBJECTIVES: To assess the efficacy and safety of single-dose tranexamic acid on the blood transfusion rate and outcomes of patients with complex kidney stones undergoing percutaneous nephrolithotomy (PCNL). PATIENTS AND METHODS: In a randomised, double-blinded, placebo-controlled trial, 192 patients with complex kidney stone (Guy's Stone Scores III-IV) were prospectively enrolled and randomised (1:1 ratio) to receive either one dose of tranexamic acid (1 g) or a placebo at the time of anaesthetic induction for PCNL. The primary outcome measure was the occurrence rate of perioperative blood transfusion. The secondary outcome measures included blood loss, operative time, stone-free rate (SFR), and complications. ClinicalTrials.gov identifier: NCT02966236. RESULTS: The overall risk of receiving a blood transfusion was reduced in the tranexamic acid group (2.2% vs 10.4%; relative risk, 0.21, 95% confidence interval [CI] 0.03-0.76, P = 0.033; number-needed-to-treat: 12). Patients randomised to the tranexamic acid group had a higher immediate and 3-month SFR compared with those in the placebo group (29% vs 14.7%, odds ratio [OR] 2.37, 95% CI 1.15-4.87, P = 0.019, and 46.2% vs 28.1%, OR 2.20, 95% CI 1.20-4.02, P = 0.011, respectively). Faster haemoglobin recovery occurred in patients in the tranexamic acid group (mean, 21.3 days; P = 0.001). No statistical differences were found in operative time and complications between groups. CONCLUSIONS: Tranexamic acid administration is safe and reduces the need for blood transfusion by five-times in patients with complex kidney stones undergoing PCNL. Moreover, tranexamic acid may contribute to better stone clearance rate and faster haemoglobin recovery without increasing complications. A single dose of tranexamic acid at the time of anaesthetic induction could be considered standard clinical practice for patients with complex kidney stones undergoing PCNL.

Acute kidney injury and percutaneous nephrolithotomy: incidence and predictive factors.

INTRODUCTION AND OBJECTIVE: Percutaneous nephrolithotomy (PCNL) is the treatment of choice for patients with large stones. The risk of acute kidney injury (AKI) has not been reported in the Western world. Our objective was to assess the frequency of AKI in patients undergoing PCNL and to identify independent predictors of AKI. METHODS: A retrospective review of PCNL cases performed between January 2014 and June 2019 was reformed. Demographic, laboratory, and intraoperative date were obtained. Perioperative AKI was defined as (1) Increase in serum creatinine by ≥ 0.3 mg/dL (≥ 26.5 micromol/L) within 48 h, or (2) increase in serum creatinine to ≥ 1.5 times baseline. Multivariable logistic regression analysis was performed to determine the factors influencing AKI. A p value of 0.05 was considered significant. RESULTS: A total of 566 patients were included. Mean age was 58 ± 14.4 years. The frequency of AKI was 4.4% (n = 25). The risk factors for AKI after PCNL were having a baseline creatinine > 1.54 mg/dl (p = 0.03, odds ratio [OR] = 2.66, confidence interval [CI] = 1.07-6.6), and a preoperative hemoglobin of less than 10.6 g/dL (p = 0.02, odds ratio [OR] = 2.47, confidence interval [CI] = 1.09-5.5). Patients without AKI had a median hospitalization of 2 days, while those with an AKI were hospitalized for a median of 3 days, and this difference was statistically significant (p < 0.001). CONCLUSIONS: Perioperative AKI occurs in 4.4% of patients undergoing PCNL. Preoperative hemoglobin and serum creatinine can identify those at increased risk, in whom it may be important to avoid nephrotoxic agents.

Ureteral Diameter as Predictor of Ureteral Injury during Ureteral Access Sheath Placement.

PURPOSE: We determined the association between ureteral diameter and ureteral injury during ureteral access sheath placement. MATERIALS AND METHODS: Patients were prospectively enrolled in the study from July 2014 to September 2015. All patients underwent preoperative noncontrast computerized tomography and had a 12Fr to 14Fr ureteral access sheath placement without pre-stenting. A measurement of proximal ureteral diameter was carried out by 2 urologists and 1 radiologist. Ureteral wall injuries were evaluated by 2 endourologists using the 5-grade classification. RESULTS: A total of 68 patients were included and the overall success rate for sheath placement was 94.1% (64). Among this group 46 patients (71.9%) had evidence of any type of injury to the ureter wall and the rate of high grade injuries was 26.1% (12). The ureteral diameter of patients who had a high grade injury was significantly smaller compared to those with low grade injuries (mean±SD 3.29±0.46 mm vs 4.5±0.97 mm, p <0.001). On multivariate analysis narrower proximal ureteral diameter was associated with a higher risk of high grade ureteral injury (OR 2.8, 95% CI 1.9-3.4, p <0.001), regardless of age, gender, body mass index, and middle and distal ureteral diameter. CONCLUSIONS: The proximal ureteral diameter is associated with high grade ureteral injury. A smaller ureteral diameter increases the risk and the severity of ureteral injury. Therefore, preoperative measurement of the ureteral diameter is recommended for ureteral access sheath placement to predict the risk of ureteral injury.

SKOPE-Study of Ketorolac vs Opioid for Pain after Endoscopy: A Double-Blinded Randomized Control Trial in Patients Undergoing Ureteroscopy.

PURPOSE: Pain is the leading cause of unplanned emergency department visits and readmissions after ureteroscopy, making postoperative analgesic stewardship a priority given the current opioid epidemic. We conducted a double-blinded, randomized controlled trial, with noninferiority design, comparing nonsteroidal anti-inflammatory drugs to opiates for postoperative pain control in patients undergoing ureteroscopy for urolithiasis. MATERIALS AND METHODS: Patients were randomized and blinded to either oxycodone (5 mg) or ketorolac (10 mg), taken as needed, with 3 nonblinded oxycodone rescue pills for breakthrough pain. Primary study outcome was visual analogue scale pain score on postoperative days 1-5. Secondary outcomes included medication utilization, side effects, and Ureteral Stent Symptom Questionnaire scores. RESULTS: A total of 81 patients were included (43 oxycodone, 38 ketorolac). The 2 groups had comparable patient, stone, and perioperative characteristics. No differences were found in postoperative pain scores, study medication or rescue pill usage, or side effects. Higher maximum pain scores on days 1-5 (p <0.05) and higher questionnaire score (28.1 vs 21.7, p=0.045) correlated with analgesic usage, irrespective of treatment group. Patients receiving ketorolac reported significantly fewer days confined to bed (mean±SD 1.3±1.3 vs 2.3±2.6, p=0.02). There was no difference in unscheduled postoperative physician encounters. CONCLUSIONS: This is the first double-blinded randomized controlled trial comparing nonsteroidal anti-inflammatory drugs and opiates post-ureteroscopy, and demonstrates noninferiority of nonsteroidal anti-inflammatory drugs in pain control with similar efficacy, safety profile, physician contact and notably, earlier convalescence compared to the opioid group. This provides strong evidence against routine opioid use post-ureteroscopy, justifying continued investigation into reducing postoperative opiate prescriptions.

A Randomized Controlled Trial of Preoperative Prophylactic Antibiotics for Percutaneous Nephrolithotomy in Moderate to High Infectious Risk Population: A Report from the EDGE Consortium.

PURPOSE: Postoperative infectious related complications are not uncommon after percutaneous nephrolithotomy. Previously, we noted that 7 days of antibiotics did not decrease sepsis rates compared to just perioperative antibiotics in a low risk percutaneous nephrolithotomy population. This study aimed to compare the same regimens in individuals at moderate to high risk for sepsis undergoing percutaneous nephrolithotomy. MATERIALS AND METHODS: Patients were prospectively randomized in this multi-institutional study to either 2 days or 7 days of preoperative antibiotics. Enrolled patients had stones requiring percutaneous nephrolithotomy and had either a positive preoperative urine culture or existing indwelling urinary drainage tube. Primary outcome was difference in sepsis rates between the groups. Secondary outcomes included rate of nonseptic bacteriuria, stone-free rate and length of stay. RESULTS: A total of 123 patients at 7 institutions were analyzed. There was no difference in sepsis rates between groups on univariate analysis. Similarly, there were no differences in nonseptic bacteriuria, stone-free rate and length of stay. On multivariate analysis, 2 days of antibiotics increased the risk of sepsis compared to 7 days of antibiotics (OR 3.1, 95% CI 1.1-8.9, p=0.031). Patients receiving antibiotics for 2 days had higher rates of staghorn calculus than the 7-day group (58% vs 32%, p=0.006) but post hoc subanalysis did not demonstrate increased sepsis in the staghorn only group. CONCLUSIONS: Giving 7 days of preoperative antibiotics vs 2 days decreases the risk of sepsis in moderate to high risk percutaneous nephrolithotomy patients. Future guidelines should consider infectious risk stratification for percutaneous nephrolithotomy antibiotic recommendations.

Combined top-down approach with low-power thulium laser enucleation of prostate: evaluation of one-year functional outcomes.

OBJECTIVES: To evaluate the safety and efficacy of combined top and down low power thulium laser enucleation of the prostate (ThuLEP). PATIENTS AND METHODS: Between May 2017 and May 2019, after institutional board review approval, successfully consented patients underwent combined top and down low power ThuLEP. We used a 30 -W Thulium laser with a 550 µm laser fiber and a 26 Fr continuous flow resectoscope. We collected data related to prostate size, enucleation time, morcellation time, perioperative complications, and early outcomes. RESULTS: Sixty patients underwent combined Top and down low power ThuLEP with mean age 67 ± 8. Acute urine retention was the main indication for surgery in 22% of patients, while the remaining had mean IPPS score 26 ± 3. The mean prostate volume was 102 ± 25 ml and the mean Qmax was 6 ± 2 ml/sec. Mean operative time was 103 ± 25 min, while; mean enucleation time was 80 ± 12 min, and mean morcellation time was 17 ± 6 min. The mean enucleated prostate volume was 73 ± 16 g and the mean hemoglobin drop was 1 ± 0.2 mg/dl. There was no need for blood transfusion and the mean hospital stay was 18 ± 4 h and catheters were removed on discharge. The 1st visit was at one month, and we observed significant mean Qmax improvement18 ± 5 ml/s. Our results showed no significant change of IIEF-5 score at 12-month follow-up compared to baseline. CONCLUSION: Low-power Thulium enucleation with a combined top and down technique provided a safe and efficacious outcome, that may reduce strenuous wrist flexion and eliminate the need for high-power Thulium laser device.

Long-term ureteroscopic management of upper tract urothelial carcinoma: 28-year single-centre experience.

BACKGROUND: Long-term survival outcomes of patients who undergo endoscopic management of non-invasive upper tract urothelial carcinoma remain uncertain. The longest mean follow-up period in previous studies was 6.1 years. This study reports the long-term outcomes of patients with upper tract urothelial carcinoma who underwent ureteroscopic ablation at a single institution over a 28-year period. METHODS: We identified all patients who underwent ureteroscopic management of upper tract urothelial carcinoma as their primary treatment at our institution between January 1991 and April 2011. Survival outcomes, including overall survival, cancer-specific survival, upper-tract recurrence-free survival and renal unit survival, were estimated using Kaplan-Meier methodology. RESULTS: A total of 15 patients underwent endoscopic management, with a mean age at diagnosis of 66 years. All patients underwent ureteroscopy, and biopsy-confirmed pathology was obtained. Median (range; mean) follow-up was 11.7 (2.3-20.9, 11.9) years. Upper tract recurrence occurred in 87% (n = 13) of patients. Twenty percent (n = 3) of patients proceeded to nephroureterectomy. The estimated cancer-specific survival rate was 93% at 5, 10, 15 and 20 years. Estimated overall survival rates were 86, 80, 54 and 20% at 5, 10, 15 and 20 years. Only one patient experienced cancer-specific mortality. The estimated mean and median overall survival times were 14.5 and 16.6 years, respectively. The estimated mean cancer-specific survival time was not reached. CONCLUSIONS: Although upper tract recurrence is common, endoscopic management of non-invasive upper tract urothelial carcinoma provides a 90% cancer-specific survival rate at 20 years in selected patients.

Stent duration and increased pain in the hours after ureteral stent removal.

INTRODUCTION To assess the relationship between pain after ureteral stent removal and patient and procedural factors. MATERIALS AND METHODS: A validated survey designed to assess the relationship between quality of life and treatment decisions in kidney stone disease was randomly distributed to patients with a history of a ureteral stent in seven medical centers across North America participating in an endourology research collaborative between July 2016 and June 2018. The primary outcome was increased pain after ureteral stent removal. Statistical analyses were performed using Chi-square and multiple logistic regression. RESULTS: A total of 327 surveys were analyzed. Twenty seven percent of patients reported increased pain in the hours after ureteral stent removal. Patients with a stent ≤ 7 days were significantly more likely to experience pain after stent removal compared to those with a stent > 7 days (33.3% versus 22.8%, p = 0.04). Female gender (OR: 2.41, 95% CI: 1.42-4.10) was associated with increased pain after stent removal, while increasing age was inversely associated (OR: 0.52, 95% CI: 0.36-0.74). After adjustment, patients with a stent > 7 days were significantly less likely to report pain in the hours after removal (OR: 0.59, 95% CI: 0.35-0.99). CONCLUSIONS: Approximately one in four patients will experience increased pain after ureteral stent removal. Female patients, younger patients, and patients with a stent ≤ 7 days were more likely to experience an increase in pain immediately following stent removal. Understanding factors associated with post-stent removal pain may be helpful in counseling patients at high risk stent removal morbidity.

High pressure endoscopic irrigation: impact on renal histology.

PURPOSE: High intra-renal pressures during flexible ureteroscopy have been associated with adverse renal tissue changes as well as pyelovenous backflow. Our objective was to investigate the effect of various intra-renal pressures on histologic changes and fluid extravasation during simulated ureteroscopy. MATERIALS AND METHODS: Twenty-four juvenile pig kidneys with intact ureters were cannulated with an Olympus flexible ureteroscope with and without a ureteral access sheath and subjected to India ink-infused saline irrigation for 30 minutes at constant pressures ranging from sphygmomanometer settings of 50mm, 100mm and 200mmHg. Renal tissue samples were collected, processed and stained, and were evaluated by a blinded pathologist for depth of ink penetration into renal parenchyma as a percentage of total parenchymal thickness from urothelium to renal capsule. RESULTS: The mean percentage of tissue penetration for kidneys with ink present in the cortical tubules at sphygmomanometer pressure settings of 50, 100, and 200mm Hg without a ureteral access sheath was 33.1, 31.0 and 99.3%, respectively and with ureteral access sheath was 0, 0 and 18.8%, respectively. Overall, kidneys with an access sheath demonstrated a smaller mean tissue penetration among all pressure compared to kidneys without a sheath (6.3% vs. 54.5%, p=0.0354). Of kidneys with sheath placement, 11% demonstrated any ink compared to 56% of kidneys without sheath placement. CONCLUSIONS: Pressurized endoscopic irrigation leads to significant extravasation of fluid into the renal parenchyma. Higher intra-renal pressures were associated with increased penetration of irrigant during ureteroscopy in an ex-vivo porcine model.

The use of outpatient opioid medication for acute renal colic and ureteral stents: Insights from a multi-institutional patient survey
.

AIMS: To investigate the main reasons for use of opioids during acute episodes of renal colic and for ureteral stent symptoms post-operatively. MATERIAL AND METHODS: A survey assessing the impact of decreased quality of life and use of opioid pain medication was distributed to patients with a history of ureteral stent at seven academic centers between July 2016 and June 2018. RESULTS: A total of 365 surveys were completed. Opioid use for stone (63.9%) and stent-related pain (39.0%) was common among respondents. When assessing whether patients used more opioids for stone or stent-related pain, 47.7% reported using more for stone pain while 15.0% reported using more for stent pain. 22.6% of patients required opioids for stent-related pain and not stone pain. Increasing patient age was found to be negatively associated with using opioids for stent-related pain (OR: 0.4, 95% CI: 0.3 - 0.6). Increasing age was also found to be negatively associated with opioid use for stone pain (OR: 0.6, 95% CI: 0.4 - 0.8). Patients with a greater number of prior stones had 3.2 times the odds of using opioids for stone pain, in our adjusted model (95% CI: 2.1 - 4.7). CONCLUSION: Patients with more prior stone episodes are more likely to have used opioids for their most recent episode. Although ureteral stents have been shown to be associated with a decreased quality of life, we showed that the use of opioids for stent-related pain is less than that for stone pain. Younger patients are less likely to tolerate a stent without opioid analgesics.

Comparison of automated irrigation systems using an in vitro ureteroscopy model.

INTRODUCTION: Two automated irrigation systems have been released for use during endoscopic procedures such as ureteroscopy: the Cogentix RocaFlow® (CRF) and Thermedx FluidSmart® (TFS). Accurate pressure control using automated systems may help providers maintain irrigation pressures within a safe range while also providing clear visualization. Our objective was to directly compare these systems based on their pressure accuracy, pressure-flow relationships, and fluid heating capabilities in order to help providers better utilize the temperature and pressure settings of each system. MATERIALS AND METHODS: An in vitro ureteroscopy model was used for testing, consisting of a short semirigid ureteroscope (6/7, 5F, 31cm Wolf 425612) connected to a continuous digital pressure transducer (Meriam m1550). Each system pressure output and flow-rate, via 100mL beaker filling time, was measured using multiple trials at pressure settings between 30 and 300mmHg. Output fluid temperature was monitored using a digital thermometer (Omega DP25-TH). RESULTS: The pressure output of both systems exceeded the desired setting across the entire tested range, a difference of 15.7±2.4mmHg for the TFS compared to 5.2±1.5mmHg for the CRF (p < 0.0001). Related to this finding, the TFS also had slightly higher flow rates across all trials (7±2mL/min). Temperature testing revealed a similar maximum temperature of 34.0°C with both systems, however, the TFS peaked after only 8 minutes and started to plateau as early as 4-5 minutes into the test, while the CRF took over 18 minutes to reach a similar peak. CONCLUSIONS: Our in vitro ureteroscopy testing found that the CRF system had better pressure accuracy than the TFS system but with noticeably slower fluid heating capabilities. Each system provided steady irrigation at safe pressures within their expected operating parameters with small differences in performance that should not limit their ability to provide steady irrigation at safe pressures.

Staghorn renal stones: what the urologist needs to know.

Patients with staghorn renal stones are challenging cases, requiring careful preoperative evaluation and close follow-up to avoid stone recurrence. In this article we aim to discuss the main topics related to staghorn renal stones with focus on surgical approach. Most of staghorn renal stones are composed of struvite (magnesium ammonium phosphate) and are linked to urinary tract infection by urease-producing pathogens. Preoperative computed tomography scan and careful evaluation of all urine cultures made prior surgery are essential for a well-planning surgical approach and a right antibiotics choice. Gold standard surgical technique is the percutaneous nephrolithotomy (PCNL). In cases of impossible percutaneous renal access, anatrophic nephrolithotomy is an alternative. Shockwave lithotripsy and flexible ureteroscopy are useful tools to treat residual fragments that can be left after treatment of complete staghorn renal stone. PCNL can be performed in supine or prone position according to surgeon's experience. Tranexamic acid can be used to avoid bleeding. To check postoperative stone-free status, computed tomography is the most accurate imaging exam, but ultrasound combined to KUB is an option. Intra-operative high-resolution fluoroscopy and flexible nephroscopy have been described as an alternative for looking at residual fragments and save radiation exposure. The main goals of treatment are stone-free status, infection eradication, and recurrence prevention. Long-term or short-term antibiotic therapy is recommended and regular control imaging exams and urine culture should be done.

Use of the Quick Sequential Organ Failure Assessment Score for Prediction of Intensive Care Unit Admission Due to Septic Shock after Percutaneous Nephrolithotomy: A Multicenter Study.

PURPOSE: Recent studies have demonstrated that quick sequential organ failure assessment criteria may be more accurate than systemic inflammatory response syndrome criteria to predict postoperative sepsis. In this study we evaluated the ability of these 2 criteria to predict septic shock after percutaneous nephrolithotomy. MATERIALS AND METHODS: We performed a retrospective multicenter study in 320 patients who underwent percutaneous nephrolithotomy at a total of 8 institutions. The criteria for quick sequential organ failure assessment and systemic inflammatory response syndrome were collected 24 hours postoperatively. The study primary outcome was postoperative septic shock. Secondary outcomes included 30 and 90-day emergency department visits, and the hospital readmission rate. RESULTS: Three of the 320 patients (0.9%) met the criteria for postoperative septic shock. These 3 patients had positive criteria for quick sequential organ failure assessment and systemic inflammatory response syndrome. Of the entire cohort 23 patients (7%) met quick sequential organ failure assessment criteria and 103 (32%) met systemic inflammatory response syndrome criteria. Specificity for postoperative sepsis was significantly higher for quick sequential organ failure assessment than for systemic inflammatory response syndrome (93.3% vs 68.4%, McNemar test p <0.001). The positive predictive value was 13% for quick sequential organ failure assessment criteria and 2.9% for systemic inflammatory response syndrome criteria. On multivariate logistic regression systemic inflammatory response syndrome criteria significantly predicted an increased probability of the patient receiving a transfusion (ß = 1.234, p <0.001). Positive quick sequential organ failure assessment criteria significantly predicted an increased probability of an emergency department visit within 30 days (ß = 1.495, p <0.05), operative complications (ß = 1.811, p <0.001) and transfusions (p <0.001). The main limitation of the study is that it was retrospective. CONCLUSIONS: Quick sequential organ failure assessment criteria were superior to systemic inflammatory response syndrome criteria to predict infectious complications after percutaneous nephrolithotomy.

The safety wire with a ureteral access sheath - does it hurt more than it helps?

INTRODUCTION: Studies indicate that with a safety wire in the ureter, an increased amount of force is necessary to advance ureteral access sheaths up to the proximal ureter. Theoretically, the compression of the ureter with the wire could lead to an increase in number and severity of ureteral injuries secondary to placement of a sheath. This prospective study aims to evaluate if there is a correlation between the use of a safety wire and ureteral injury from sheath placement by evaluating the location of the wire in relation to the injury after ureteroscopy. MATERIALS AND METHODS: Fifty-nine consecutive patients underwent ureteroscopy for upper tract urinary stone disease. A 12/14 French ureteral access sheath was used with a safety wire in place. Ureteroscopy during withdrawal of the sheath was video recorded and reviewed by a blinded observer. Visible ureteral injuries were graded per the Traxer ureteral injury scale and the proximity of the wire to the injury was noted. RESULTS: Thirty-one of 59 patients (52.4%) had a ureteral injury secondary to access sheath placement. Eighteen (30.5%) injuries were low-grade, 13 (22.0%) were high-grade (grade 2 and 3) and there were no grade 4 injuries. A total of 10 (32.3%) injuries occurred on the same side as the wire while 67.7% were on the contralateral side of the ureter. Of the injuries that occurred on the same side as the wire, 80% were grade 1 injuries and 2 (20%) were grade 3. Statistical analysis did not show a significant relationship between high/low injury grade and side of injury (p value = 0.088). This suggests that there is no association of between the safety wire and development of high injury. CONCLUSION: There is no association between the location of the safety wire and ureteral injury if injury occurs during the placement of a ureteral access sheath. This suggests that the use of a safety wire does not add significant morbidity to the procedure.

Endoscopic guided PCNL in the prone split-leg position versus supine PCNL: a comparative analysis stratified by Guy's stone score.

INTRODUCTION: The optimal patient positioning for percutaneous nephrolithotomy (PCNL) based on the complexity of stone burden is not yet defined. Thus, we aimed to evaluate the intraoperative parameters, effectiveness and complications of patients undergoing PCNL between the endoscopic-guided prone split-leg PCNL (ePSL) and the supine PCNL by stratifying patients according to Guy's stone score (GSS). MATERIALS AND METHODS: A retrospective chart review was conducted of patients undergoing PCNL at two high-volume tertiary referral centers. At one center, patients underwent PCNL using the ePSL technique, while at the second center, patients underwent PCNL in supine. Patient demographics and stone characteristics, operative details, complications and effectiveness were compared between groups. The impact of obesity was also investigated. RESULTS: Of 830 subjects, a total of 449 (54%) underwent PCNL in ePSL and 381 (46%) in supine. The ePSL group had a greater mean age and body mass index. No statistical differences were found in gender, serum chemistry and Charlson comorbidity index. After stratifying patients by GSS, the differences in baseline stone burden between PSL and supine lost significance and both groups could be compared. Complications were not statistically different between both groups. Univariate analysis demonstrated that multiple tracts and lower pole access were more prevalent in supine. In addition, for GSS1-3, ePSL was correlated with reduced operative time, radiation exposure, length of hospital stay and need for secondary procedure. Multivariate analysis correlated ePSL with lower radiation exposure and need for secondary procedures (p = 0.01). In comparison to the whole trial population, the same tendencies were appreciated for obese cohort. CONCLUSIONS: This is the first report focusing on the performance differences between ePSL and supine PCNL stratified by GSS. Both techniques are safe, with a low rate of complications. For GSS1-3, ePSL reduces radiation exposure and requires less need for both multiple access and secondary procedure.

A comprehensive literature-based equation to compare cost-effectiveness of a flexible ureteroscopy program with single-use versus reusable devices.

PURPOSE: To critically review all literature concerning the cost-effectiveness of flexible ureteroscopy comparing single-use with reusable scopes. MATERIALS AND METHODS: A systematic online literature review was performed in PubMed, Embase and Google Scholar databases. All factors potentially affecting surgical costs or clinical outcomes were considered. Prospective assessments, case control and case series studies were included. RESULTS: 741 studies were found. Of those, 18 were duplicated and 77 were not related to urology procedures. Of the remaining 646 studies, 59 were considered of relevance and selected for further analysis. Stone free and complication rates were similar between single-use and reusable scopes. Operative time was in average 20% shorter with digital scopes, single-use or not. Reusable digital scopes seem to last longer than optic ones, though scope longevity is very variable worldwide. New scopes usually last four times more than refurbished ones and single-use ureterorenoscopes have good resilience throughout long cases. Longer scope longevity is achieved with Cidex and if a dedicated nurse takes care of the sterilization process. The main surgical factors that negatively impact device longevity are lower pole pathologies, large stone burden and non-use of a ureteral access sheath. We have built a comprehensive fi nancial costeffective decision model to fl exible ureteroscope acquisition. CONCLUSIONS: The cost-effectiveness of a fl exible ureteroscopy program is dependent of several aspects. We have developed a equation to allow a literature-based and adaptable decision model to every interested stakeholder. Disposable devices are already a reality and will progressively become the standard as manufacturing price falls.