Search

Introduction and Objective: Prior literature had demonstrated increased stone burden and higher rates of staged surgery in individuals of lower socioeconomic status (SES). Low SES individuals are more likely to experience delays in definitive stone surgery after initial presentation to the emergency department (ED) for kidney stones. This study aims to investigate the relationship between delays in definitive kidney stone surgery and the subsequent need for percutaneous nephrolithotomy (PNL) and/or staged surgical procedures using a statewide data set. Methods: This retrospective cohort study gathered longitudinal data from 2009 to 2018 using the California Department of Health Care Access and Information data set. Patient demographic characteristics, comorbidities, diagnosis/procedure codes, and distance were analyzed. Complex stone surgery was defined as initial PNL and/or undergoing more than one procedure within 365 days of initial intervention. Results: A total of 1,816,093 billing encounters from 947,798 patients were screened, resulting in 44,835 patients with ED visits for kidney stones followed by a urologic stone procedure. Multivariable analysis revealed that relative to patients who underwent surgery within 1 month of initial ED visit for stone disease, patients were at increased odds of undergoing complex surgery if waiting ≥6 months (odds ratio [OR] 1.18, p  = 0.022), ≥1 year (OR 1.29, p  < 0.001), and ≥3 years (OR 1.43, p  < 0.001). Conclusions: Delays in definitive stone surgery after initial ED encounter for stone disease were associated with increased likelihood of undergoing a complex stone treatment.

Introduction and Objectives: Lack of access to urologic specialists is approaching crisis levels as the number of urologists is decreasing, while the demand for urologic care is increasing. The financial implications of this have not been explored. The objective of this study is to examine the impact of access and other patient factors on cost to treat urolithiasis. We hypothesized that markers of poor access would associate with higher costs of surgical encounters for patients presenting with urolithiasis. Methods: A retrospective review of prospectively collected data from the Registry for Stones of the Kidney and Ureter (ReSKU) from September 2015 to July 2018 was conducted to investigate characteristics of surgical patients treated for urinary stone disease. Univariate analysis was performed using the Welch two-sample t -test. Multivariate analysis was performed using logistic regression. Statistical analysis was performed in R version 3.5. Results: When taking into account age, delayed presentation, procedure type, stone size >20 mm, American Society of Anesthesiologists (ASA) code, gender, race, income, distance, urologist density, body mass index, diabetes, infection, education, language, insurance, and stone complexity, patients undergoing percutaneous nephrolithotomy procedure ( p  < 0.001; odds ratio [OR] 12.9, confidence interval [CI] 4.05-48.5), urologist density in the bottom quartile ( p  = 0.014; OR 4.66, CI 1.40-16.9), diabetes ( p  = 0.018; OR 4.38, CI 1.32-15.6), and infection ( p  = 0.007; OR 4.51, CI 1.55-14.0) were the only variables statistically significant for association with top quartile of total cost. Conclusions: Surgical encounter costs are largely dictated by patient clinical factors, but low regional urologist density appears to independently predicted for high-cost stone surgery. Increasing patients' access to a urologist may prove to be financially beneficial in the longitudinal reduction in health care costs for stone disease.

Introduction: American Urological Association (AUA) guidelines recommend percutaneous nephrolithotomy (PCNL) for total stone burden greater than 20 mm, yet it is unclear if the number of stones affects adherence to this guideline. We aim to assess the impact of stone multiplicity on the choice of ureteroscopy (URS) vs PCNL as a first-line therapy for patients with high burden (>20 mm), and examine whether the AUA guideline-discordant care impacts patient outcomes. Materials and Methods: Data were collected from the Registry for Stones of the Kidney and Ureter (ReSKU) database, a prospectively collected registry of patients with stone disease. Multivariate logistic regression (MLR) was used to estimate the association between stone multiplicity and the decision to perform URS for high stone burden (>20 mm) patients. MLR was further used to estimate the association between performing URS and the following outcomes: stone-free rate, need for a second operation, and complications. Postoperative hospital stay was compared between patients receiving URS vs PCNL using Student's t -test. Results: One hundred twenty-five patients were included in this analysis. For patients with total stone burden exceeding 20 mm, those with more than three stones had roughly nine times the likelihood of undergoing URS over PCNL compared with patients with a single stone (adjusted odds ratio 9.21, confidence interval [95% CI] 2.55-40.58, p  = 0.001). Stone-free rates, Clavien-Dindo scores, and frequency of second-look operations did not differ significantly between URS and PCNL patients. URS patients were discharged an average of 1.26 days earlier than patients who received PCNL (95% CI 0.72-1.81, p  < 0.001). Discussion: Stone multiplicity strongly predicts which patients with stone burden >20 mm will undergo URS and who will undergo PCNL. These deviations from AUA guidelines do not appear to worsen patient outcomes. These results suggest that careful consideration of each patient may warrant deviation from guidelines.

Introduction: Cystinuria is a genetic disorder marked by elevated urinary cystine excretion and recurrent cystine nephrolithiasis. Interestingly, despite seemingly similar contralateral renal anatomy, a subset of cystinuric patients consistently form stones in only one kidney. The aim of this study is to evaluate clinical outcomes in unilateral vs bilateral cystine stone formers., Patients and Methods: We performed a retrospective case-control study of cystinuric patients evaluated and treated at the University of California, San Francisco between 1994 and 2015 and categorized patients as either unilateral or bilateral stone formers. Clinical presentation, baseline patient demographics, stone procedures, medical therapy regimens, and long-term renal function were compared between the two groups., Results: A total of 42 cystine stone patients (22 female, 20 male) were included in the analysis. The median age at first presentation was 18.5 years and median age at study conclusion was 45.5 years. Two-thirds of patients (n = 28) had a history of bilateral stones, whereas one-third (n = 14) had unilateral stones. Medical therapy regimens were similar between groups. Despite an increased average number of lifetime surgeries (7.5 sessions for bilateral vs 3.7 sessions for unilateral, p < 0.05), there was no significant difference in medians of the most recent glomerular filtration rate when compared with unilateral stone formers (81.5 vs 95 mL/min, respectively; p = 0.28)., Conclusions: The majority of cystinuric patients within our cohort form stones bilaterally during their lifetime, and require more surgical interventions than unilateral stone formers. Despite this, overall renal function is well preserved in unilateral and bilateral cystinuric stone formers treated with minimally invasive stone extraction procedures.

Purpose: Careful decontamination and sterilization of reusable flexible ureteroscopes used in ureterorenoscopy cases prevent the spread of infectious pathogens to patients and technicians. However, inefficient reprocessing and unavailability of ureteroscopes sent out for repair can contribute to expensive operating room (OR) delays. Time-driven activity-based costing (TDABC) was applied to describe the time and costs involved in reprocessing., Materials and Methods: Direct observation and timing were performed for all steps in reprocessing of reusable flexible ureteroscopes following operative procedures. Estimated times needed for each step by which damaged ureteroscopes identified during reprocessing are sent for repair were characterized through interviews with purchasing analyst staff. Process maps were created for reprocessing and repair detailing individual step times and their variances. Cost data for labor and disposables used were applied to calculate per minute and average step costs., Results: Ten ureteroscopes were followed through reprocessing. Process mapping for ureteroscope reprocessing averaged 229.0 ± 74.4 minutes, whereas sending a ureteroscope for repair required an estimated 143 minutes per repair. Most steps demonstrated low variance between timed observations. Ureteroscope drying was the longest and highest variance step at 126.5 ± 55.7 minutes and was highly dependent on manual air flushing through the ureteroscope working channel and ureteroscope positioning in the drying cabinet. Total costs for reprocessing totaled $96.13 per episode, including the cost of labor and disposable items., Conclusions: Utilizing TDABC delineates the full spectrum of costs associated with ureteroscope reprocessing and identifies areas for process improvement to drive value-based care. At our institution, ureteroscope drying was one clearly identified target area. Implementing training in ureteroscope drying technique could save up to 2 hours per reprocessing event, potentially preventing expensive OR delays.

Ultrasound-guided renal access for percutaneous nephrolithotomy (PCNL) is a safe, effective, and low-cost procedure commonly performed worldwide, but a technique underutilized by urologists in the United States. The purpose of this article is to familiarize the practicing urologist with methods for ultrasound guidance for percutaneous renal access. We discuss two alternative techniques for gaining renal access for PCNL under ultrasound guidance. We also describe a novel technique of using the puncture needle to reposition residual stone fragments to avoid additional tract dilation. With appropriate training, ultrasound-guided renal access for PCNL can lead to reduced radiation exposure, accurate renal access, and excellent stone-free success rates and clinical outcomes.

Background and Purpose: The role of magnesium in urinary stone formation remains undefined. In vivo, magnesium inhibits stone formation in hyperoxaluric rats, and small clinical studies suggest a protective effect of magnesium supplementation in calcium oxalate stone formers. We performed a retrospective review of more than 7,000 stone patients to see if there is a relation between urinary magnesium and other stone risk variable constituents., Materials and Methods: A national database of stone formers categorized by residential ZIP code was queried, and, using strict inclusion criteria, 2,147 patients having pure calcium oxalate stones were identified. There were 1,912 (89%) eumagnesuric (43-246 mg/24 hours) and 235 (11%) hypomagnesuric (<43 mg/24 hours) patients., Results: Patients with decreased urinary magnesium excretion had significantly less daily urine excretion of citrate, calcium, oxalate, uric acid, and sodium than the eumagnesuric group (p < 0.0001). Stone recurrence was slightly more common in the hypomagnesuric group, although the difference was not statistically significant. The percentage of patients voiding <1 L of urine per day was significantly higher in the hypomagnesuric group. In the eumagnesuric group, males outnumbered females 2:1, whereas hypomagnesuric patients showed a female predominance of 1.4:1., Conclusion: The beneficial effects of urinary magnesium on stone formation may be less than previously reported. The role of oral magnesium supplementation and the subsequent increase in urinary magnesium in calcium urinary stone formation remains unknown. Our data suggest that its effect on or interaction with citrate may be influential on urinary citrate concentrations. If magnesium has a protective effect, it may work through pathways that enhance citrate excretion.

Background and Purpose: Increasing evidence suggests that Randall's plaques contribute to the pathogenesis of urinary stone formation. The purpose of our study was to evaluate the urinary risk factors of stone patients who underwent endoscopic mapping of their calices for Randall's plaques., Patients and Materials: Patients (N = 143) having endoscopic procedures to remove upper tract calculi or for other purposes underwent mapping of their calices for Randall's plaques. Plaque incidence and pattern were correlated with the stone composition and urinary risk factors found on subsequent metabolic evaluation., Results: Papillary plaques were found more commonly in patients having calcium oxalate stones than in patients with other stone types and patients without a history of stones. Papillary plaque incidence and pattern did not correlate with any specific urinary risk factor; however, patients with plaques tended to exhibit a higher incidence of all risk factors. Plaque severity tended to be greater in patients exhibiting hypercalciuria., Conclusions: Randall's plaques are found most frequently in patients with calcium oxalate stones and are most important in the pathogenesis of calcium oxalate nephrolithiasis. Stone patients with papillary plaques are more likely to exhibit abnormalities in their urinary milieu than are patients without papillary plaques.

We compared quantitative urinary cystine values in stone-forming family members and unaffected relatives based on an index stone-forming patient. A family pedigree of 39 members was identified. Quantitative urinalyses and serum biochemical profiles were collected with the subjects on similar diets over 72 hours. Detailed medical histories were obtained. Three family members are stone-forming cystinuric patients with a mean urinary cystine excretion of 496 mg/g of creatinine per day. Six persons without a history of stones (mean age 50) had a mean urinary cystine excretion of 364 mg/g of creatinine per day. Thirty-four family members had elevated urinary cystine concentrations (mean 151 mg/g of creatinine per day), and only two family members had normal urinary cystine excretion. Fifteen subjects with elevated urinary cystine values (> 150 mg/g of creatinine per day) had no history of urinary stones despite a mean age of 44 years. Urinary electrolytes and volumes were similar in the stone-forming and non-stone-forming groups. Thirty-nine per cent of the persons from this family pedigree had elevated quantitative urinary cystine concentrations and no history of urinary stones despite a mean age of 44 years. Acalculous cystinuria is an elevated urinary cystine concentration without evidence of urinary stone disease. Despite abnormal urinary cystine excretion, acalculous cystinuria does not necessarily culminate in clinical urinary stone disease.

The utility of indwelling double-J ureteral stents during extracorporeal shockwave lithotripsy (SWL) of renal calculi is ill defined. We evaluated 179 patients treated with SWL for small (< 20 mm in diameter) solitary renal calculi with (N = 27) or without (N = 152) indwelling ureteral stents. There was no significant difference in the stone-free rates at 1 month (both 52%) and 3 months (61% nonstented group v 67% stented group; P = 0.45) or in the retreatment rates (13.3% nonstented group v 14.8% stented group; P = 0.60). The incidence and severity of pain/renal colic were similar for the two treatment groups. There was minimal morbidity associated with SWL in either group. Placement of double-J stents for the purpose of improving stone-free rates, alleviating pain, or preventing ureteral obstruction in conjunction with SWL of solitary renal calculi < 20 mm in diameter is unnecessary.

The dissolutive effects of sodium fluoride on human calcium stone particles were investigated in an in vitro model. Stone particles composed of 65% calcium oxalate and 35% calcium phosphate dissolved in a dose-dependent fashion with NaF exposure. Stone particles exposed to 60 mM NaF had a 17% reduction in particle mass after 24 hours and a 62% reduction after 7 days in comparison with experimental controls bathed in physiologic normal saline. The systemic toxicity of the dose of oral fluoride necessary to achieve the optimal tested urinary concentrations would likely preclude oral administration, but NaF may have an adjunctive role in upper urinary tract irrigation for residual stone fragments after lithotripsy or in chronic low-dose oral administration for prophylaxis against recurrent calcium nephrolithiasis.

Ureteroscopy (URS) and extracorporeal shockwave lithotripsy (SWL) battle for supremacy in the management distal ureteral calculi. In order to clarify issues surrounding this controversy, we created a decision tree modeling URS or SWL with literature-based probabilities and used as endpoints both cost and patient preferences. Ureteroscopy was more successful than single-session or multiple-session SWL, 92.1% v 74.3% or 84.5%, and had a lower retreatment/complication rate. Although initial SWL was only slightly more expensive than URS, $4,420 v $4,337, the difference increased when the additional costs of complications and retreatment were calculated, $6,745 v $5,555. Using values for an "average" patient, SWL was preferred to URS in terms of patient satisfaction. The most important factors distinguishing between URS and SWL were the success of treatment, the cost of initial therapy, and patient attitudes toward unplanned ancillary procedures and retreatment. Although no alteration of success rates and cost figures within reasonable ranges made URS less cost-effective than SWL, individual differences in patients' aversion for complications allowed URS to be preferred to SWL in some situations. Therefore, SWL is less cost-effective than URS and is not necessarily preferred by patients. The physician should be aware of the principal determinants of the choice between URS and SWL treatment of distal ureteral calculi.

In order to compare the effects of intraperitoneal and extraperitoneal insufflation of CO2, we obtained blood gas measurements and chest radiographs in dogs during insufflation into three sites: the peritoneal cavity alone, the retroperitoneal space with communication into the peritoneal cavity, and the retroperitoneal space alone. The blood pH fell a mean of 0.11 +/- 0.03 and the PaCO2 rose a mean of 16.0 +/- 3.7 mm Hg when insufflation included the peritoneal cavity, whereas when insufflation was limited to the retroperitoneum, the pH fell a mean of 0.05 +/- 0.03 and the PaCO2 rose a mean of 7.5 +/- 2.8 mm Hg. Extrapleural thoracic dissection of gas was noted in one animal after insufflation limited to the retroperitoneal space. These findings confirm that there is significant absorption of CO2 from the peritoneal cavity during laparoscopy with CO2 insufflation, whether the pneumoperitoneum is primary or occurs secondary to retroperitoneal insufflation. If the insufflated gas is limited to the retroperitoneal space, however, the absorption of CO2 appears to be reduced in this animal model. The risk of thoracic dissection of gas may be greater during extraperitoneal insufflation than during intraperitoneal insufflation.

We present five patients with urinary matrix calculi, which, in contrast to the normally brittle calcigerous calculi, are soft, pliable, and amorphous. Common clinical features include a history of calcigerous stone disease, renal surgery, urinary obstruction or stasis, and chronic infection with Proteus species or coliforms. The diagnosis is usually made at surgery, but certain preoperative radiographic findings may be suggestive. Matrix calculi are radiolucent on plain abdominal films, although their appearance on nonenhanced CT scans is similar to that of calcigerous calculi despite their small mineral content. Extracorporeal shockwave lithotripsy is ineffective; open or percutaneous techniques are necessary. Histologic inspection reveals laminar concentric rings of organized matrix with an orderly, layered deposition of minerals. Histochemical investigation can provide insight into the possible sequence of events in normal calculogenesis. The successful management of urinary matrix calculi depends on a high index of suspicion and a thorough knowledge of their clinicopathologic features.

We report a new technique for the management of ureterovesical junction stenosis in a renal transplant recipient. Endoscopic retrograde resection of a bladder window permitted direct retroperitoneal vision and longitudinal incision of the distal ureter. Ureteral and bladder mucosa were in close proximity and were stabilized with a double-J catheter. This alternative transmural transvesical ureteroneocystostomy had minimal morbidity and may be an alternative to traditional open surgical repair of these lesions.

The genitourinary system is a common source of disease in many animal species as well as humans, and the practice of comparative endourology is possible because of advances in the past decade in minimally invasive human surgery. Zoo veterinarians may have limited formal urologic training, and increasingly limited public funding resources now leave most community zoos without specialized endourologic equipment or expertise. Urologists may offer or be called on to assist in the diagnosis and management of often rare and valuable species, providing services and expertise previously limited to humans. Such cases may provide intellectual and technical challenges beyond those seen in clinical practice, while applying the same basic universal urologic principles. We describe a cooperative approach to the management of animal urologic disorders based on a 5-year experience as consultants to the San Francisco Zoo and encourage an interdisciplinary approach between urologists and their local zoos where this may be useful in the preservation and maintenance of these valuable and important public resources.

We investigated the use of bisphosphonates, analogs of pyrophosphate that bind to mineralized tissue, to image renal calculi in vivo. Twenty stone-bearing kidneys in 15 patients without urinary obstruction were studied. 99mTechnetium-methylene diphosphonate was injected intravenously followed by 20 mg of furosemide 4 hours later, and images were obtained by gamma counter for 30 minutes. Areas of increased uptake corresponded with the sites of calculi, and even small or radiolucent calculi were easily seen. Counts in the region of each kidney, the L4 vertebral body, and a background area were combined to calculate a scintigram index (SI) for each kidney. The mean SI of the stone-bearing kidneys was 4.8 +/- 3.5 v 1.3 +/- 0.4 for the normal kidneys. There was correlation of the SI with stone composition and size but not with radiographic density. After correction for size, the SI of stone-bearing kidneys remained significantly higher than the SI of normal kidneys, but the differences between calculi of different compositions were diminished. Nonetheless, high SI values were associated with soft types of calculi and low values with hard types. Future investigations will reveal if this association is constant and if there is any relation between bisphosphonate uptake and response to lithotripsy. The sensitivity of urolithoscintigraphy to image small or radiolucent calculi may make it an effective technique for the assessment of residual fragments after lithotripsy.

Pyelocaliceal diverticula are cystic urine collections within the renal parenchyma communicating with the collecting system. They occur in 0.2% to 0.5% of the population and often contain calculi. Flank pain is the most common complaint, and most lesions are diagnosed by intravenous urography. In the past, treatment has required open renal surgery, with potential loss of renal function, or prolonged percutaneous procedures. We propose surgical treatment of caliceal diverticula by laparoscopic unroofing and fulguration. The benefits include renal preservation as well as decreased morbidity and an earlier return to work for the patient.

Suprapubic urinary diversion for the management of lesions of the bladder outlet or urethra has been facilitated by the advent of percutaneous access techniques. Prior to percutaneous endourologic techniques, an open surgical approach was necessary when the transurethral route was impassable. A variety of percutaneous suprapubic cystostomy techniques have evolved in recent years. These have been based on several different access principles and offer the urologist a number of options. Selection of an individual technique is usually a matter of preference and familiarity with a particular manufacturer's product. The list of indications for such an approach is diverse and continues to expand.