Interdisciplinary planning improves radiologist obtained access for percutaneous nephrolithotomy.

INTRODUCTION: Proper antegrade access for percutaneous nephrolithotomy (PCNL) is essential for success but can be challenging. Previous work evaluating access obtained by interventional radiology (IR), largely in the emergent setting, has shown high rates of additional access at the time of PCNL. We hypothesize that efforts to improve pre-procedural communication between urology and IR can impact the utility of the access for subsequent PCNL. MATERIAL AND METHODS: We conducted a retrospective review of patients undergoing PCNL at a single hospital from January 2011 to December 2022. Adult patients undergoing PCNL with established preoperative access were included. RESULTS: A total of 141 cases were identified with preoperative access. A total of 111 patients had evidence of planning with IR prior to antegrade access. There were high rates of anatomic abnormality (50%) and staghorn calculus (53%). Patients with planned access had higher body mass index (BMI). While preoperative access was initially utilized in 97% of cases, 6% required additional access to be obtained intraoperatively; this included a low rate of new access in those that were previously discussed with IR (4% vs. 17%, p = 0.02). Overall stone free rates (91%), rates of second stage procedures (55%) and complications (14%) were similar between planned and unplanned groups. CONCLUSION: In this retrospective study of complex patients with large stone burden presenting for PCNL with preoperative antegrade access obtained by IR, the rate of new access was far lower than prior reports. This was likely influenced by urologist involvement in planning access.

Accuracy of Radiology Reports for Obstructing Ureteral Stone Size in the Emergency Department.

OBJECTIVE: To evaluate the number of dimensions of obstructing ureteral stones in the emergency department (ED) described in present-day radiology computed tomography reports and assess for measurement discrepancies between radiologist and urologist review. METHODS: We conducted a single-center retrospective study of patients who presented to the ED with unilateral, solitary, obstructing ureteral stones from March 2018 to March 2021. Stone size in each reported dimension recorded by the radiologist was extracted from the chart and then compared to size independently measured by one of our urologists for all 3 stone dimensions. Our primary outcome was the number of stone dimensions included in the radiology report. RESULTS: In total, 181 patients were included for analysis. 82.3% of radiology reports described the stone in one dimension, 15% in two dimensions, and 2.7% in three dimensions. There was a significant difference in median maximal stone size between radiologist and urologist measurement (5.5 vs 6.5 mm, respectively, P < .001). One hundred fourteen stones (62%) had the maximal measurement recorded in the craniocaudal (CC) dimension by urologist review. Only 26% of radiology reports had the CC measurement included in the radiology report. CONCLUSION: Ureteral stone size in a present-day ED cohort is still frequently measured in only 1 or 2 dimensions. In many cases, this is associated with an absence of a reported CC measurement. Inadequate characterization of stone size may affect acute management. This study hopes to encourage reporting of all three dimensions of obstructing ureteral stones in the ED setting for improvements in patient management.

Linear relationship between absorbed radiation dose and pulse rate during fluoroscopy.

PURPOSE: To identify the relationship between fluoroscopy pulse rate and absorbed radiation dose. We compared absorbed radiation dose with common proxy measurements such as fluoroscopy time and C-arm reported dose. METHODS: Using a simulated patient model, 60 s fluoroscopy exposures were performed using pulse rates of 30, 8, 4, 2, and 1 pulse(s) per second. Each experiment was performed with both standard and low-dose settings using a GE OEC 9800 plus C-arm. Landauer nanoDot™ OSL dosimeters were used to measure the absorbed radiation dose. RESULTS: Fluoroscopy pulse rate and absorbed radiation dose demonstrated a linear correlation for both standard (R2 = 0.995, p < 0.001) and low-dose (R2 = 0.998, p < 0.001) settings. For any given pulse rate, using the low-dose setting reduced absorbed radiation dose by 58 ± 2.8%. Fluoroscopy time demonstrated a linear relationship with absorbed radiation dose for both standard (R2 = 0.996, p < 0.001) and low-dose (R2 = 0.991, p < 0.001) settings, but did not change with use of the low-dose setting. C-arm reported radiation dose correlated linearly with absorbed dose (R2 = 0.999) but consistently under-estimated measured values by an average of 49 ± 3.5%. Using a combination of 1 pulse-per-second and low-dose fluoroscopy, absorbed dose was reduced by 97.7 ± 0.1% compared to standard dose and 30 pulse-per-second settings. CONCLUSION: Absorbed radiation dose decreases linearly with fluoroscopy pulse rate during equivalent exposure times. Adjusting fluoroscopy pulse rate and utilizing low-dose settings significantly reduces overall absorbed radiation exposure by up to 98%.

International Alliance of Urolithiasis (IAU) guidelines on the metabolic evaluation and medical management of urolithiasis.

The aim of this study was to construct the fourth in a series of guidelines on the treatment of urolithiasis by the International Alliance of Urolithiasis (IAU) that by providing a clinical framework for the metabolic evaluation, prevention, and follow-up of patients with urolithiasis based on the best available published literature. All recommendations were summarized following a systematic review and assessment of the literature in the PubMed database from January 1976 to June 2022. Each generated recommendation was graded using a modified GRADE methodology. Guideline recommendations were developed that addressed the following topics: initial evaluation, metabolic testing, dietary measures, medical management, and follow-up of recurrent stone formers. It was emphasized by the Panel that prevention of new stone formation is as important as the surgical removal of the stones. Although general preventive measures may be effective in reducing stone recurrence rates in some patients, specific medical and dietary management should be well considered and eventually applied in an individualized manner based on the outcomes of metabolic work-up, stone analysis and some certain patient related factors. A detailed follow-up of each case is essential depending on the metabolic activity of each individual patient.

Prospective randomized trial of 2 versus 12-weeks of postoperative antibiotics after percutaneous nephrolithotomy in complex patients with infection-related kidney stones.

PURPOSE: Treatment of struvite kidney stones requires complete surgical stone removal combined with antibiotic therapy to eliminate urinary tract infections and preventive measures to reduce stone recurrence. The optimal duration of antibiotic therapy is unknown. We sought to determine if 2- or 12-weeks of antibiotics post percutaneous nephrolithotomy (PNL) for infection stones resulted in better outcomes for stone recurrence and positive urine cultures. MATERIAL AND METHODS: This multi-center, prospective randomized trial evaluated patients with the clinical diagnosis of infection stones. Patients were randomized to 2- or 12-weeks of postoperative oral antibiotics (nitrofurantoin or culture-specific antibiotic) and included if residual fragments were ≤4 mm on computed tomography imaging after PNL. Imaging and urine analyses were performed at 3-, 6-, and 12-months post-procedure. RESULTS: Thirty-eight patients were enrolled and randomized to either 2-weeks (n = 20) or 12-weeks (n = 18) of antibiotic therapy post-PNL. Eleven patients were excluded due to residual fragments >4 mm, and 3 patients were lost to follow-up. The primary outcome was the stone-free rate (SFR) at 6 months post-PNL. At 3-, 6-, and 12-months follow-up, SFRs were 72.7% versus 80.0%, 70.0% versus 57.1%, 80.0% versus 57.1% (p = ns), between 2- and 12-week-groups, respectively. At 3-, 6-, and 12-months follow-up, positive urine cultures were 50.0% versus 37.5%, 50.0% versus 83.3%, and 37.5% versus 100% between 2- and 12-week groups, respectively (p = ns). CONCLUSIONS: For patients with stone removal following PNL, neither 2-weeks nor 12-weeks of postoperative oral antibiotics is superior to prevent stones and recurrent positive urine cultures.

Subcapsular hematoma in a solitary kidney: successful conservative management.

Subcapsular renal hematoma (SRH) is an infrequent complication of urologic interventions but can lead to serious consequences in patients with a solitary kidney. We present our experience with conservative management of a patient with a solitary kidney and multiple medical comorbidities who developed a SRH and subsequent renal failure after nephroureteral catheter placement. Literature on the management of this unique clinical scenario is limited. Herein, we share our experience with supportive care and temporary dialysis in a medically complex patient whose outcome is complete renal recovery.

Urinary Metabolic Disturbances During Topiramate Use and their Reversibility Following Drug Cessation.

OBJECTIVE: To understand the metabolic disturbances of stone formers currently taking topiramate and to examine the reversibility of these disturbances with cessation of the medication. MATERIALS AND METHODS: All progress notes written by 5 endourologists from a single academic center were retrospectively reviewed from January 2010 to July 2020 containing the words "topiramate" or "topamax." Inclusion criteria were age >18 and presence of either a 24-hour urine sample or stone analysis while on topiramate. In addition, a subgroup of 18 patients with 24-hour urine samples before and after stopping topiramate were identified. RESULTS: A total of 93 patients were identified and included for final analysis. Twenty-four hour urine samples were available in 67 patients and showed mean citrate excretion of 331 ± 322 mg/d, mean pH of 6.6 ± 0.5, and mean calcium phosphate supersaturation of 1.9 ± 1.1. In the subgroup analysis urinary citrate excretion increased from 225 mg/d to 614 mg/d (P <.01) and pH decreased from 6.59 ± 0.54 to 6.33 ± 0.47 (P = .06) after stopping topiramate. In addition, 114 stone events occurred in 73 distinct patients, with 50% of stones either pure or majority (≥50%) calcium phosphate by composition. CONCLUSION: Hypocitraturia and elevated pH is seen during topiramate use with resultant higher rate of calcium phosphate stone formation compared to the general population. Stopping topiramate leads to significant increase in citrate excretion and normalization of pH. These metabolic disturbances appear to be reversible with medication cessation.

Defining 24-hour urine parameters and kidney stone risk of student athletes.

PURPOSE: Dehydration is a risk factor for kidney stone formation. Studying populations that may experience dehydration without a known increased incidence of stone formation may help understand stone formation and prevention. High-caliber athletes represent such a population. We characterized the urinary environment of high-caliber athletes utilizing 24-hour urine collections with comparison to non-athlete controls. MATERIALS AND METHODS: After Institutional Review Board (IRB) and National Collegiate Athletic Association (NCAA) compliance officer approval, 74 college-student athletes and 20 non-athletes were enrolled. Demographics, medical history, and sport of participation were recorded. Participants were asked to provide 24-hour urine collections as well as diet and activity logs at the time of urine collection. Standard stone risk parameters were assessed and compared to litholink reference standards. RESULTS: 34 athletes and 10 non-athletes provided at least one 24-hour urine specimen for evaluation. Athletes had a high prevalence of urinary risks for stone formation including low volume (median 1.46 L), low citrate, high sodium, high calcium (females), and high uric acid (males). However, athletes also had a high prevalence of known stone-protective factors such as high urine magnesium. Athletes had a lower urine pH but high supersaturation of uric acid and calcium oxalate compared to non-athletes. CONCLUSION: Student athletes appear to have a high prevalence of urinary risk factors for stone formation such as dehydration, high calcium, high uric acid, high sodium, and low citrate. Overall stone risk in this population may be offset by increased levels of stone-protective factors such as magnesium. Further study of this population may help generate hypotheses for effective stone prevention strategies in the general population.

Safety During Ureteroscopy: Radiation, Eyes, and Ergonomics.

It is known that urologic surgeons are at risk of work-place injury due to the physical requirements of operating and exposure to hazards. These hazards include radiation, exposure to body fluids, use of laser energy, and orthopedic injury due to the physical nature of operating. The risks that these hazards present can be mitigated by implementing several evidence-based safety measures. The methods to protect against radiation exposure include keeping radiation usage in the operating room as low as reasonably achievable, donning lead aprons, and wearing protective glasses. Additionally, protective glasses decrease the risk of eye injury from laser injury and exposure to body fluids. Finally, practicing sound surgical ergonomics is essential to minimize the risk of orthopedic injury and promote career longevity. The interventions discussed herein are simple and easy to implement in one's daily practice of urology.

Minimizing radiation dose in management of stone disease: how to achieve 'ALARA'.

PURPOSE OF REVIEW: Exposure to radiation is known to have adverse effects such as secondary malignancies. Patients with nephrolithiasis are exposed to radiation in the workup and treatment of their condition. Furthermore, exposure to radiation is often repeated due to the high recurrence rate of nephrolithiasis. RECENT FINDINGS: We discuss practices inside and outside of the operating room to strive to keep radiation exposure as low as reasonably achievable (ALARA) for patients being treated for nephrolithiasis. These efforts include reduced dose computed tomography scans, fluoroless surgical techniques and new alternative technologies. SUMMARY: Maintaining radiation exposure ALARA for our patients is increasingly practical. The urologist must make every effort to adhere to ALARA principles to protect patients from the stochastic effects of radiation.

Unconventional Use of the Lithoclast to Aid in the Treatment of Large Distal Ureteral Stone Burden in a Patient With a Ureterocele.

INTRODUCTION: Large ureteral stone burden can present significant challenges for the urologist to treat. Here we present the retrograde use of the Lithoclast Select, in a dilated distal ureter after incision of a ureterocele. METHODS: The patient is a 64 year-old female with large distal ureteral stone burden, with approximately 15 1-2 cm stones. She presented with significant right flank pain, urinary urgency, frequency, dysuria, and recurrent urinary tract infections. RESULTS: A 22-French rigid cystoscope was inserted into the bladder. Urethral outlet was normal. Patient was noted to have 2 right-sided ureteral orifices, consistent with a completely duplex system. At the medial right ureteral orifice a very large ureterocele was noted. The lower pole system was scoped and stone free. The ureter to the upper pole moiety was scoped and a large stone burden within the distal ureter was visualized. The Plasmacise Gyrus was used to incise the anterior part of the ureter by inserting the Plasmacise into the ureteral orifice and tenting it anteriorly. The 24-French nephroscope was then inserted into the distal ureter. Graspers were used to extract many fragments however several were unable to be extracted from the distal ureter due to their size and thus were fragmented and evacuated with the ultrasonic lithoclast within the distal ureter. A 365-µ laser fiber was also used to fragment some of the stones. There were no complications. CT Scan 4 months post operatively was negative for stone recurrence. Last follow up was 15 months postprocedure where the patient was doing well. CONCLUSIONS: Utilization of the rigid nephroscope and ultrasonic lithotripter in a female patient with a dilated distal ureter with a capacious or incised ureterocele is safe and effective, allowing for treatment of greater than 15 cm total distal ureteral stone burden.

Optimizing Outcomes in Urological Surgery: Intraoperative Patient Safety and Physiological Considerations.

INTRODUCTION: Intraoperative surgical outcomes are influenced by a wide variety of patient, surgeon and institutional factors. The current literature lacks comprehensive resources that describe best practices in preventing patient safety events and optimizing patient physiology during urological surgery. METHODS: A multidisciplinary panel of subject matter experts (urologists, nurses, anesthesiologists) was convened to evaluate the existing literature, create a white paper and disseminate this to urological providers. Focusing on intraoperative patient safety and physiology, a narrative review was undertaken and relevant guidelines and practical interventions were highlighted. RESULTS: Patient safety is optimized by preventing surgical site infections, wrong site surgery, venous thromboembolism, falls/positioning injuries, laser/fire injuries, excessive radiation exposure and harm from the adoption of new technology. Goals for intraoperative physiological parameters (temperature, glucose, fluid balance) are addressed as well as analgesic and anesthetic considerations in urological patients. In addition, practical tools are provided to assist in the quality improvement process. CONCLUSIONS: This article summarizes intraoperative factors related to patient safety and optimal physiology that can impact urological surgical outcomes. This overview can be used as a practical guide for process improvement to optimize the quality of intraoperative care.

Endoscopic diagnosis of renal pseudoaneurysm following ureteroscopy.

Renal pseudoaneurysm following ureteroscopy is a rare cause of hematuria usually diagnosed and treated with angiography and embolization. Here we present a case of a small pseudoaneurysm causing intermittent flank pain and gross hematuria associated with clot retention initially diagnosed during ureteroscopy and subsequently treated with a combined endourologic and endovascular approach.

Trends in renal calculus composition and 24-hour urine analyses in patients with neurologically derived musculoskeletal deficiencies

ABSTRACT Purpose: To better characterize metabolic stone risk in patients with neurologically derived musculoskeletal deficiencies (NDMD) by determining how patient characteristics relate to renal calculus composition and 24-hour urine parameters. Materials and Methods: We performed a retrospective cohort study of adult patients with neurologically derived musculoskeletal deficiencies presenting to our multidisciplinary Kidney Stone Clinic. Patients with a diagnosis of NDMD, at least one 24-hour urine collection, and one chemical stone analysis were included in the analysis. Calculi were classified as primarily metabolic or elevated pH. We assessed in clinical factors, demographics, and urine metabolites for differences between patients who formed primarily metabolic or elevated pH stones. Results: Over a 16-year period, 100 patients with NDMD and nephrolithiasis were identified and 41 met inclusion criteria. Thirty percent (12 / 41) of patients had purely metabolic calculi. Patients with metabolic calculi were significantly more likely to be obese (median body mass index 30.3kg / m2 versus 25.9kg / m2), void spontaneously (75% vs. 6.9%), and have low urine volumes (100% vs. 69%). Patients who formed elevated pH stones were more likely to have positive preoperative urine cultures with urease splitting organisms (58.6% vs. 16.7%) and be hyperoxaluric and hypocitraturic on 24-hour urine analysis (37mg / day and 265mg / day versus 29mg / day and 523mg / day). Conclusions: Among patients with NDMD, metabolic factors may play a more significant role in renal calculus formation than previously believed. There is still a high incidence of carbonate apatite calculi, which could be attributed to bacteriuria. However, obesity, low urine volumes, hypocitraturia, and hyperoxaluria suggest an underrecognized metabolic contribution to stone formation in this population.

Trends in the Usage of Contrast Allergy Prophylaxis for Endourologic Procedures.

OBJECTIVE: To characterize current practice patterns of urologists in the management of intravenous (IV) contrast allergy in the setting of endourologic procedures. METHODS: A survey was administered to all members of the Endourological Society to assess management of IV contrast allergy prior to ureteroscopy (URS) and percutaneous nephrolithotomy (PCNL). Treatment regimens, reports of adverse outcomes, and demographics of respondents were also collected. Data were analyzed using chi-square tests. RESULTS: The response rate was 15% (325/2100). A total of 21% and 28% of respondents reported giving prophylaxis prior to URS and PCNL, respectively. Nearly 3% of respondents reported having observed a severe adverse reaction to intraluminal contrast in the past. Approximately half reported giving prophylaxis only 1 hour prior to the procedure. Most respondents (77%) completed a fellowship, the most common being endourology. Chi-square analysis revealed a significant difference between giving prophylaxis for URS or PCNL and the respective case volumes (for URS, X2 = 8.3, P= .004; for PCNL, X2 = 8.5, P= .003) where urologists with the lowest and highest case volumes were more likely to give prophylaxis (Fig. 1). There was no significant difference between giving prophylaxis for URS or PCNL and recency of residency, fellowship training, practice setting, or practice type. CONCLUSION: Most urologists do not give prophylaxis for patients with IV contrast allergy prior to URS and PCNL. Further studies are needed to evaluate the necessity of prophylaxis as well as to establish clear guidelines.

Modeling the Incidence of Secondary Malignancy Related to Ionizing Radiation Use in the Management of Nephrolithiasis.

OBJECTIVE: To model the risk of secondary malignancy and associated mortality due to ionizing radiation from the evaluation and management of nephrolithiasis. METHODS: A PUBMED-based literature search was performed to identify model inputs, specifically annual incidence of nephrolithiasis sub-stratified by age and gender and radiation exposure associated with nephrolithiasis episodes. Estimates of age and gender specific radiation-induced malignancy and mortality rates were obtained from the BEIR VII Phase 2 report with dose extrapolation using the linear no-threshold model. RESULTS: Incidence of new diagnoses of nephrolithiasis ranged from 42/100,000 in males 20-30 years old to 248/100,000 in males 60-70 years old. Radiation exposure per nephrolithiasis episode was 37.3 mSv over a 2-year period. Data regarding average stone episodes per patient with nephrolithiasis was limited and conservatively estimated at 1.5. Modeled lifetime attributable risk of secondary malignancy and subsequent mortality in individual stone patients ranged from 0.096% and 0.085%, respectively, in males over the age of 70 to 0.59% and 0.39% in females 20-30 years old. In the USA, overall incidence of secondary malignancy and associated mortality related to nephrolithiasis management was calculated to be 862.7 and 545.3 cases/year, respectively. CONCLUSION: This model suggests that ionizing radiation from the management of nephrolithiasis carries a small but significant risk of causing secondary malignancy. This knowledge must be considered when using modalities that involve radiation in the diagnosis and therapeutic management of nephrolithiasis.

Trends in renal calculus composition and 24-hour urine analyses in patients with neurologically derived musculoskeletal deficiencies.

PURPOSE: To better characterize metabolic stone risk in patients with neurologically derived musculoskeletal deficiencies (NDMD) by determining how patient characteristics relate to renal calculus composition and 24-hour urine parameters. MATERIALS AND METHODS: We performed a retrospective cohort study of adult patients with neurologically derived musculoskeletal deficiencies presenting to our multidisciplinary Kidney Stone Clinic. Patients with a diagnosis of NDMD, at least one 24-hour urine collection, and one chemical stone analysis were included in the analysis. Calculi were classified as primarily metabolic or elevated pH. We assessed in clinical factors, demographics, and urine metabolites for differences between patients who formed primarily metabolic or elevated pH stones. RESULTS: Over a 16-year period, 100 patients with NDMD and nephrolithiasis were identified and 41 met inclusion criteria. Thirty percent (12 / 41) of patients had purely metabolic calculi. Patients with metabolic calculi were significantly more likely to be obese (median body mass index 30.3kg / m2 versus 25.9kg / m2), void spontaneously (75% vs. 6.9%), and have low urine volumes (100% vs. 69%). Patients who formed elevated pH stones were more likely to have positive preoperative urine cultures with urease splitting organisms (58.6% vs. 16.7%) and be hyperoxaluric and hypocitraturic on 24-hour urine analysis (37mg / day and 265mg / day versus 29mg / day and 523mg / day). CONCLUSIONS: Among patients with NDMD, metabolic factors may play a more significant role in renal calculus formation than previously believed. There is still a high incidence of carbonate apatite calculi, which could be attributed to bacteriuria. However, obesity, low urine volumes, hypocitraturia, and hyperoxaluria suggest an underrecognized metabolic contribution to stone formation in this population.

Identifying and managing the risks of medical ionizing radiation in endourology.

INTRODUCTION: The risks of exposure to medical ionizing radiation is of increasing concern both among medical professionals and the general public. Patients with nephrolithiasis are exposed to high levels of ionizing radiation through both diagnostic and therapeutic modalities. Endourologists who perform a high-volume of fluoroscopy guided procedures are also exposed to significant quantities of ionizing radiation. The combination of judicious use of radiation-based imaging modalities, application of new imaging techniques such as ultra-low dose computed tomography (CT) scan, and modifying use of current technology such as increasing ultrasound and pulsed fluoroscopy utilization offers the possibility of significantly reducing radiation exposure. We present a review of the literature regarding the risks of medical ionizing radiation to patients and surgeons as it pertains to the field of endourology and interventions that can be performed to limit this exposure. MATERIALS AND METHODS: A review of the current state of the literature was performed using MEDLINE and PubMed. Interventions designed to limit patient and surgeon radiation exposure were identified and analyzed. Summaries of the data were compiled and synthesized in the body of the text. RESULTS: While no level 1 evidence exists demonstrating the risk of secondary malignancy with radiation exposure, the preponderance of evidence suggests a dose and age dependent increase in malignancy risk from ionizing radiation. Patients with nephrolithiasis were exposed to an average effective dose of 37mSv over a 2 year period. Multiple evidence-based interventions to limit patient and surgeon radiation exposure and associated risk were identified. CONCLUSION: Current evidence suggest an age and dose dependent risk of secondary malignancy from ionizing radiation. Urologists must act in accordance with ALARA principles to safely manage nephrolithiasis while minimizing radiation exposure.