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

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

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.

Estimating the health-related quality of life of kidney stone patients: initial results from the Wisconsin Stone Quality of Life Machine-Learning Algorithm (WISQOL-MLA).

OBJECTIVE: To build the Wisconsin Stone Quality of Life Machine-Learning Algorithm (WISQOL-MLA) to predict urolithiasis patients' health-related quality of life (HRQoL) based on demographic, symptomatic and clinical data collected for the validation of the Wisconsin Stone Quality-of-Life (WISQOL) questionnaire, an HRQoL measurement tool designed specifically for patients with kidney stones. MATERIAL AND METHODS: We used data from 3206 stone patients from 16 centres. We used gradient-boosting and deep-learning models to predict HRQoL scores. We also stratified HRQoL scores by quintile. The dataset was split using a standard 70%/10%/20% training/validation/testing ratio. Regression performance was evaluated using Pearson's correlation. Classification was evaluated with an area under the receiver-operating characteristic curve (AUROC). RESULTS: Gradient boosting obtained a test correlation of 0.62. Deep learning obtained a correlation of 0.59. Multivariate regression achieved a correlation of 0.44. Quintile stratification of all patients in the WISQOL dataset obtained an average test AUROC of 0.70 for the five classes. The model performed best in identifying the lowest (0.79) and highest quintiles (0.83) of HRQoL. Feature importance analysis showed that the model weighs in clinically relevant factors to estimate HRQoL, such as symptomatic status, body mass index and age. CONCLUSIONS: Harnessing the power of the WISQOL questionnaire, our initial results indicate that the WISQOL-MLA can adequately predict a stone patient's HRQoL from readily available clinical information. The algorithm adequately relies on relevant clinical factors to make its HRQoL predictions. Future improvements to the model are needed for direct clinical applications.

Does "MyChart" Benefit "My" Surgery? A Look at the Impact of Electronic Patient Portals on Patient Experience.

PURPOSE: Electronic patient portals can be beneficial in providing direct engagement and clarity to avoid unnecessary extra provider encounters. In this study we assessed whether portal usage among endourology patients affected telephone call frequency, unscheduled physician visits, emergency department presentations and complication rates. MATERIALS AND METHODS: We conducted a retrospective chart review of patients undergoing elective endourology procedures by a single surgeon at a tertiary urology center from July 2017 to July 2018. Patient demographics, operative details, patient portal (MyChart) registration, patient initiated MyChart messages, telephone encounters, unscheduled physician visits and emergency department presentations during a 1-month period before and after the procedure were identified. Logistic regression analysis assessed relationships between MyChart use and study outcomes. RESULTS: We identified 313 patients (200 MyChart users, 113 nonusers) who underwent 374 procedures. MyChart users were younger (age 56 vs 61, p=0.0011) and more likely to be married (69.5% vs 48.7%, p=0.0004). MyChart users made fewer telephone calls before (1.1 vs 1.2, p=0.005) and after procedure (0.9 vs 1.3, p=0.029), and had fewer emergency department visits (8 vs 18, p=0.0005) than nonusers. On multivariable analysis MyChart nonusers were 4.55 (95% CI 1.92-11.11) times more likely to have an unscheduled clinic visit (p=0.0006), 1.92 (95% CI 1.075-3.333) times more likely to have an emergency department visit (p=0.028) and 2.7 (95% CI 1.43-5.26) times more likely to have a postoperative complication (p=0.0026). CONCLUSIONS: Patients undergoing endourology procedures who use MyChart make fewer telephone calls and are significantly less likely to have an unscheduled clinic/emergency department visit or a complication.

Association of Patient Age and Gender with Kidney Stone Related Quality of Life.

PURPOSE: Kidney stone formers have lower health related quality of life than nonstone formers. The North American Stone Quality of Life Consortium is a multicenter, longitudinal, prospective study of health related quality of life in patients with kidney stones using the WISQOL (Wisconsin Stone Quality of Life Questionnaire) with data on 2,052 patients from a total of 11 centers. This study is a subanalysis of cross-sectional data looking at the association of age, gender and race on health related quality of life of stone formers. MATERIALS AND METHODS: We performed multivariable analyses of ordinal logistic regression analyses to determine the impact of age, gender and race on health related quality of life, adjusting for other baseline covariates. The proportional odds assumption of ordinal logistic regression was checked. Total score and scores on 4 subdomains (social functioning, emotional functioning, stone related impact and vitality) were included. RESULTS: Median total score for all patients was 80.4. On multivariable analysis older patients had a significantly higher total health related quality of life score than younger patients (per 10-year increase OR 1.25, p <0.0001). Male patients had higher scores than females (OR 1.56, p = 0.0003) and nonCaucasian patients had lower health related quality of life than nonLatino Caucasian patients (OR 0.63, p = 0.0045). CONCLUSIONS: Younger and female patients with kidney stones have lower health related quality of life than older and male patients, respectively. NonCaucasian patients with stones also have lower health related quality of life. The clinical impact of these findings might include future implications for patient counseling, including dietary and medical management of stone disease, and potential changes to the paradigm of the surgical management of stones.

Low Income and Nonwhite Race are Strongly Associated with Worse Quality of Life in Patients with Nephrolithiasis.

PURPOSE: Kidney stones are a source of significant morbidity which have been shown to negatively impact health related quality of life. We sought to understand the association between health related quality of life, socioeconomic status and race among patients with kidney stones. MATERIALS AND METHODS: Patients with stones at a total of 11 stone centers across the United States completed the WISQOL (Wisconsin Stone Quality of Life questionnaire). The patient ZIP Code™ was used to estimate household income. A mixed effects regression model was constructed for analysis with ZIP Code as the random intercept. RESULTS: A total of 2,057 stone formers completed the WISQOL. Lower income was independently associated with significantly lower health related quality of life (ß = 0.372, p = 0.014), as were nonwhite race (ß = -0.299, p = 0.001), unemployed work status (ß = -0.291, p = 0.008), female gender (ß = -0.204, p <0.001), body mass index greater than 40 kg/m2 (ß = -0.380, p <0.001), 5 or more medical comorbidities (ß = -0.354, p = 0.001), severe recurrent stone formation (ß = -0.146, p = 0.045), enrollment at an acute care visit, or a preoperative or postoperative appointment (ß = -0.548, p <0.001) and recent stone symptoms (ß = -0.892, p <0.001). CONCLUSIONS: Lower income, nonwhite race and unemployed work status were independently associated with lower health related quality of life among patients with kidney stones. While clinical characteristics such as body mass and stone disease severity were also associated with health related quality of life, this study shows that socioeconomic factors are similarly important. Further research to understand the specific mechanisms by which socioeconomic status and race impact health may lend insight into methods to optimize clinical treatment of stone formers and patients with other chronic diseases.

The Effect of Thiazide and Potassium Citrate Use on the Health Related Quality of Life of Patients with Urolithiasis.

PURPOSE: To our knowledge it is unknown whether the benefits of medical management of urolithiasis outweigh the potential side effects of the medications used, including potassium citrate and thiazide diuretics. Therefore, we evaluated the relationship between potassium citrate or thiazides and overall stone related health related quality of life. MATERIALS AND METHODS: Cross-sectional data were obtained on stone forming enrollees in the North American Stone Quality of Life Consortium. We used the WISQOL (Wisconsin Stone Quality of Life) questionnaire to compare health related quality of life between patients treated and not treated with potassium citrate or thiazide type diuretics. Additionally, the likelihood of gastrointestinal complaints was compared between those prescribed and not prescribed potassium citrate. The likelihood of fatigue and sexual complaints was also compared in those prescribed and not prescribed thiazides. RESULTS: Of the 1,511 subjects, including 787 males and 724 females, 279 were on potassium citrate and 238 were on thiazides at study enrollment. Patients prescribed potassium citrate had higher health related quality of life in each domain vs those not prescribed potassium citrate (p <0.001). Patients prescribed thiazides had higher health related quality of life in each domain compared to those not prescribed thiazide (all p <0.01). Those prescribed potassium citrate were less likely than those not prescribed potassium citrate to report nausea, stomach upset or cramps (OR 0.57, p <0.001). Patients prescribed thiazides were less likely than those not prescribed thiazides to report fatigue (OR 0.63, p = 0.004) or reduced sexual interest and/or activity (OR 0.64, p = 0.005). CONCLUSIONS: Among stone formers the use of potassium citrate and thiazides was associated with better health related quality of life across all WISQOL domains without an increased likelihood of gastrointestinal complaints and fatigue or sexual complaints, respectively. These findings may be useful when counseling patients regarding the initiation of potassium citrate or thiazides for medical management of nephrolithiasis.

Validation and Reliability of the Wisconsin Stone Quality of Life Questionnaire.

PURPOSE: WISQOL (Wisconsin Stone Quality of Life questionnaire) is a disease specific, health related quality of life measure designed for patients who form kidney stones. The purpose of this study was to demonstrate the external and convergent validity of WISQOL and assess its psychometric properties. MATERIALS AND METHODS: At the WISQOL creation site (development sample) and at 8 geographically diverse centers in the United States and Canada (consortium sample) patients with a history of kidney stones were recruited. Item response option variability, correlation patterns and internal consistency were compared between samples. Convergent validity was assessed by patients who completed both WISQOL and SF-36v2® (36-Item Short Form Health Survey, version 2). RESULTS: Results were analyzed in 1,609 patients, including 275 in the development sample and 1,334 in the consortium sample. Response option variability patterns of all items were acceptable. Internal WISQOL consistency was acceptable. Intersample score comparisons revealed few differences. For both samples the domain-total WISQOL score correlations exceeded 0.86. Item level analyses demonstrated suitable variation, allowing for discriminatory scoring. At the time that they completed WISQOL, patients with stones and stone related symptoms scored lowest for health related quality of life. Patients with stones but no symptoms and those with no stones scored higher. The convergent validity substudy confirmed the ability of WISQOL to identify stone specific decrements in health related quality of life that were not identified on SF-36v2. CONCLUSIONS: WISQOL is internally consistent and discriminates among patients with different stone statuses and symptoms. WISQOL is externally valid across the North American population. It may be used for multicenter health related quality of life studies in kidney stone disease.

Does Combination Therapy with Tamsulosin and Tolterodine Improve Ureteral Stent Discomfort Compared with Tamsulosin Alone? A Double-Blind, Randomized, Controlled Trial.

PURPOSE: Ureteral stent discomfort is a significant postoperative problem for many patients. Despite the use of narcotics and α-blockers patients often experience bothersome lower urinary tract symptoms and pain, which impair daily activities. We compared combination therapy with an α-blocker and an anticholinergic to monotherapy with an α-blocker. MATERIALS AND METHODS: A double-blind, randomized, controlled trial was performed from December 2012 to April 2014. A total of 80 patients were randomized, including 44 to the combination group (tamsulosin 0.4 mg and tolterodine early release 4 mg) and 36 to the monotherapy group (tamsulosin 0.4 mg and placebo). Patients with preexisting ureteral stent placement or current anticholinergic therapy were excluded from study. Patients completed USSQ (Urinary Stent Symptom Questionnaire) before stent placement on the day of surgery, the day after stent placement, the morning of stent removal and the day after stent removal. The questionnaire included questions regarding urinary symptoms, general health, body pain, and work and sexual history. RESULTS: A total of 80 patients (40 males and 40 females) were studied. Mean age was 51.5 vs 51.3 years (p = 0.95) and mean body mass index was 33.6 vs 31.9 kg/m(2) (p = 0.44) in monotherapy group 1 vs combination therapy group 2. Between the 2 groups there was no significant difference in urinary symptoms, body pain and activities of daily living from baseline to just before stent removal (p = 0.95, 0.40 and 0.95, respectively). Although there was no difference between the groups, both showed improvement in urinary symptoms from the time of initial stent insertion to just prior to stent removal (difference -0.50 for combination therapy and -0.40 for monotherapy). The mean stent indwelling time of 9.6 and 8.7 days in the combination and monotherapy groups, respectively, did not differ (p = 0.67). On ANOVA it had no significant impact on results (p = 0.64). CONCLUSIONS: Combination therapy with tamsulosin and tolterodine does not appear to improve urinary symptoms, bodily pain or quality of life in patients after ureteral stent placement for nephrolithiasis compared to tamsulosin alone. Both groups experienced worse urinary symptoms, pain and quality of life with a stent, suggesting that further research is necessary to improve stent discomfort.

Systemic Inflammatory Response Syndrome after Percutaneous Nephrolithotomy: A Randomized Single-Blind Clinical Trial Evaluating the Impact of Irrigation Pressure.

PURPOSE: We evaluated the impact of intraoperative irrigation pressures on the risk of systemic inflammatory response after percutaneous nephrolithotomy. MATERIALS AND METHODS: Between January 2014 and March 2015, 90 patients with renal stones planned for percutaneous nephrolithotomy were randomized between low (80 mm Hg) and high (200 mm Hg) irrigation pressure. Patient demographics, perioperative outcomes and systemic inflammatory response incidence rates were compared using the chi-square and Wilcoxon signed rank tests. RESULTS: Mean patient age, gender, body mass index and other perioperative outcomes were similar in both arms. High pressure irrigation was associated with a higher risk of systemic inflammatory response syndrome (46%) compared to low pressure irrigation (11%, p=0.0002). On multivariate analysis only high irrigation pressure, paraplegia or neurogenic bladder and nonquinolone perioperative medication were predictive of postoperative systemic inflammatory response syndrome. CONCLUSIONS: High pressure fluid irrigation fluid increases the risk of postoperative systemic inflammatory response syndrome after percutaneous nephrolithotomy.

Clinical Predictors of 30-Day Emergency Department Revisits for Patients with Ureteral Stones.

PURPOSE: Patients with ureteral stones frequently present to the emergency department for an initial evaluation with pain and/or nausea. However, a subset of these patients subsequently return to the emergency department for additional visits. We sought to identify clinical predictors of emergency department revisits. MATERIALS AND METHODS: We reviewed emergency department visits at our institution with an ICD-9 diagnosis of urolithiasis and an associated computerized tomography scan between 2010 and 2013. Computerized tomography studies were independently reviewed to confirm stone size and location, and degree of hydronephrosis. The primary outcome was a second emergency department visit within 30 days of the initial visit for reasons related to the stone. Patient characteristics and stone parameters at presentation were recorded. Univariable and multivariable analyses were done to identify factors associated with emergency department revisits. RESULTS: We reviewed the records of 1,510 patients 18 years old or older who presented to the emergency department with a diagnosis of ureteral stones confirmed by computerized tomography. Of the patients 164 (11%) revisited the emergency department within 30 days. On multivariable analysis the presence of a proximal ureteral stone, age less than 30 years and the need for intravenous narcotics in the emergency department remained independently associated with an emergency department revisit. CONCLUSIONS: Younger patients, those with proximal stones and those requiring intravenous narcotics for pain control are more likely to return to the emergency department. Consideration should be given for early followup or intervention for these patients to prevent costly emergency department returns.

Prospective trial of the detection of urolithiasis on ultralow dose (sub mSv) noncontrast computerized tomography: direct comparison against routine low dose reference standard.

PURPOSE: In this prospective trial we compared ultralow dose computerized tomography reconstruction algorithms and routine low dose computerized tomography for detecting urolithiasis. MATERIALS AND METHODS: A total of 48 consenting adults prospectively underwent routine low dose noncontrast computerized tomography immediately followed by an ultralow dose series targeted at a 70% to 90% reduction from the routine low dose technique (sub mSv range). Ultralow dose series were reconstructed with filtered back projection, and adaptive statistical and model based iterative reconstruction techniques. Transverse (axial) and coronal images were sequentially reviewed by 3 relatively inexperienced trainees, including a radiology resident, a urology fellow and an abdominal imaging fellow. Three experienced abdominal radiologists independently reviewed the routine low dose filtered back projection images, which served as the reference standard. RESULTS: The mean effective dose for the ultralow dose scans was 0.91 mSv (median 0.82), representing a mean ± SD 78% ± 5% decrease compared to the routine low dose. Overall sensitivity and positive predictive value per stone for ultralow dose computerized tomography at a 4 mm threshold was 0.91 and 0.98, respectively. Sensitivity, specificity, positive and negative predictive values, and accuracy per patient were 0.87, 1.00, 1.00, 0.94 and 0.96, respectively. At a 4 mm threshold the sensitivity and positive predictive value per stone of the ultralow dose series for filtered back projection, and adaptive statistical and model based iterative reconstruction was 0.89 and 0.96, 0.91 and 0.98, and 0.93 and 1.00, respectively. Sensitivity, specificity, positive and negative predictive values, and accuracy per patient at the 4 mm threshold were 0.82, 1.00, 1.00, 0.91 and 0.94 for filtered back projection, 0.85, 1.00, 1.00, 0.93 and 0.95 for adaptive statistical iterative reconstruction, and 0.94, 1.00, 1.00, 0.97 and 0.98 for model based iterative reconstruction, respectively. Sequential review of coronal images changed the final stone reading in 13% of cases and improved diagnostic confidence in 49%. CONCLUSIONS: At a 4 mm renal calculus size threshold ultralow dose computerized tomography is accurate for detection when referenced against routine low dose series with dose reduction to below the level of a typical 2-view plain x-ray of the kidneys, ureters and bladder. Slight differences were seen among the reconstruction algorithms. There was mild improvement with model based iterative reconstruction over filtered back projection and adaptive statistical iterative reconstruction. Coronal images improved detection and diagnostic confidence over axial images alone.

Can Perioperative Antibiotic Choice Impact Rates of Infectious Complications After Percutaneous Nephrolithotomy? A Single-Blind, Prospective Randomized Trial.

Objective: National guidelines recommend periprocedural antibiotics before percutaneous nephrolithotomy (PCNL), yet it is not clear which is superior. We conducted a randomized trial to compare two guideline-recommended antibiotics: ciprofloxacin (cipro) vs cefazolin, on PCNL outcomes, focusing on the development of systemic inflammatory response syndrome (SIRS) criteria. Methods: Adult patients who were not considered high risk for surgical or infectious complications and undergoing PCNL were randomized to receive either cipro or cefazolin perioperatively. All had negative preoperative urine cultures. Demographic and perioperative data were collected, including SIRS criteria, intraoperative urine culture, duration of hospitalization, and need for intensive care. SIRS is defined by ≥2 of the following: body temperature <96.8°F or >100.4°F, heart rate >90 bpm, respiratory rate >20 per minute, and white blood cell count <4000 or >12,000 cells/mm3. Results: One hundred forty-seven patients were enrolled and randomized (79 cefazolin and 68 cipro). All preoperative characteristics were similar (p > 0.05), except for mean age, which was higher in the cipro group (64 vs 57 years, p = 0.03). Intra- and postoperative findings were similar, with no difference between groups (p > 0.05), except a longer mean hospital stay in the cefazolin group (2 hours longer, p = 0.02). There was no difference between SIRS episodes in both univariate and multivariate analyses. Conclusions: Despite the relatively broader coverage for urinary tract pathogens with ciprofloxacin, this prospective randomized trial did not show superiority over cefazolin. Our findings therefore support two appropriate options for perioperative antibiotic prophylaxis in patients undergoing PCNL who are nonhigh risk for infectious complications.

Incidence and trends in the treatment of kidney stones in Canada A population-based cohort study.

INTRODUCTION: Our objective was to assess the incidence of kidney stones requiring acute care, trends in the surgical treatment of stones, and the demographics of stone formers in Canada. METHODS: We conducted a population-based, retrospective cohort study using administrative data from the Canadian Institute for Health Information. We included Canadian residents age >18 years, outside of Quebec, who presented between January 1, 2013, and December 31, 2018, with a kidney stone episode. This was defined as a kidney stone resulting in hospital admission, emergency department visit, or stone intervention, specifically shockwave lithotripsy (SWL), ureteroscopy (URS), or percutaneous nephrolithotomy (PCNL). RESULTS: There were 471 824 kidney stone episodes, including 184 373 interventions. The number of kidney stone episode increased from 277/100 000 in 2013 to 290/100 000 in 2018. The median age was 53 (interquartile range 41-65) years and 59.9% were male. The crude rate for stone intervention was 877/100 000. The age- and gender-standardized rate for interventions was highest in Nova Scotia and Newfoundland and Labrador, and lowest in Prince Edward Island. The most common intervention in Canada was URS (73.5%), followed by SWL (19.8%) and PCNL (6.7%). The percent utilization of SWL was highest in Manitoba, whereas for URS, it was highest in Prince Edward Island and Alberta. CONCLUSIONS: Our study provides the first population-based data on the demographics of stone formers and treatment trends across Canada. There has been a 4.7% increase in kidney stone episodes over the study period. Those presenting to hospital or requiring intervention for a kidney stone are more likely to be male, aged 41-65, and undergo URS.

Percutaneous nephrolithotomy with retrograde nephrostomy access: a forgotten technique revisited.

PURPOSE: We retrospectively assessed outcomes in a single institution series of percutaneous nephrolithotomy using retrograde nephrostomy access. MATERIALS AND METHODS: We retrospectively evaluated the records of 333 consecutive patients treated between May 2003 and July 2008. Measured variables included patient demographics, retrograde nephrostomy site, postoperative drainage, operative time, stone clearance rate and degree, requirement for secondary procedures, stone composition and complications. RESULTS: A total of 333 patients were included in study, including 162 females and 171 males with a median age of 56 years (range 17 to 87). Median hospital stay was 2 days (range 1 to 13). Antegrade access was required in 14 patients (4%) due to difficult or suboptimal anatomy. A nephrostomy tube was placed in 33 of 329 patients (10%), mainly for postoperative irrigation. Mean operative time was 76 minutes (range 25 to 246). Of the patients 79% achieved complete clearance, 19% had residual fragments 4 mm or less and 2% had significant persistent stones greater than 4 mm. Postoperatively 11 patients (3%) required shock wave lithotripsy. Analysis revealed calcium oxalate in 57% of stones, uric acid in 24%, struvite in 5% (infection stones) and other in 21%. Complications included 4 patients (1%) with significant postoperative hemorrhage, including angioembolization in 2, transfusion of 4 U packed red blood cells in 1 and observation in 1. CONCLUSIONS: The retrograde technique to establish a percutaneous nephrostomy tract for percutaneous nephrolithotomy is safe and effective with stone clearance and complication rates comparable to those of antegrade access.

Contemporary minimally invasive treatment options for renal angiomyolipomas.

Renal angiomyolipomas (AMLs) are benign renal masses that are often asymptomatic and detected incidentally. However, treatment might be necessary in symptomatic presentations or when the mass exceeds 4 cm in size. While the goal of management for renal AMLs is to relieve symptoms and prevent hemorrhage, a priority is renal function preservation, especially given the propensity of these lesions to recur. The traditional treatment for renal AMLs is renal angioembolization or surgical excision of the lesion. With advancements in minimally invasive surgery, several other modalities have now emerged for nephron sparing approaches. These include angioembolization, laparoscopic and percutaneous ablative therapies such as radiofrequency ablation, cryoablation and microwave ablation, and pure or robot-assisted laparoscopic partial nephrectomy. Given the relatively low frequency of renal AMLs requiring treatment, much of the available literature on these minimally invasive approaches is largely extrapolative, based on series on small renal masses, i.e. renal cell carcinoma (RCC). This report is based on a thorough review of the published literature to date on the minimally invasive treatment and outcomes of renal AMLs.