Variability in stone composition and metabolic correlation between kidneys in patients with bilateral nephrolithiasis.

PURPOSE: To evaluate the clinical significance of discordant stone analyses in patients undergoing bilateral ureteroscopy. MATERIALS AND METHODS: A retrospective chart review was performed for all patients undergoing stone extraction with bilateral ureteroscopy at our institution in an aim to identify patients who had bilateral stone analysis and 24-h urine chemistry data available. Stones were then classified based upon the dominant present (> 50%). Twenty-four hour urinalysis results were reviewed and statistical analysis performed comparing discordant and concordant patient populations, assessing significant differences that would potentially influence clinical management. RESULTS: We identified 79 patients (158 renal units) who had bilateral stones removed at the time of ureteroscopy. The majority of stones were classified as calcium oxalate (CaOx) (60.1%) followed by calcium phosphate (CaP) (27.8%), brushite (5.1%), uric acid (UA) (4.4%), and cystine (2.5%). Discrepancies in stone classifications were present 24% of the time. Evaluation of 24-h urinalysis results demonstrated that patients with CaOx:CaP stone discordance compared to CaOx:CaOx concordant stone formers were more likely to have an elevated pH (p = 0.02) and lower uric acid supersaturation (p = 0.01). CONCLUSIONS: Discrepancies in stone mineral content are common in patients with bilateral stone disease. A single stone analysis from one side in the setting of bilateral stone disease is insufficient for management of patients with bilateral renal stones, and may lead to mismanagement when this misrepresented information is utilized in addition to 24-h urinalysis results. At least one stone analysis should be performed from both sides during a bilateral stone extraction procedure.

Holmium laser enucleation of the prostate in Jehovah's Witness patients.

PURPOSE: To evaluate if HoLEP is a viable option for male patients with medication-refractory urinary symptoms due to an enlarged prostate who are surgical candidates, but do not accept blood product transfusion. MATERIALS AND METHODS: Between August 2008 and March 2019, nine Jehovah's Witness patients were undergoing HoLEP for relief of lower urinary tract symptoms and urinary retention. We described change in hemoglobin, change in PSA, enucleated prostate weight, enucleation and morcellation times, length of stay, and postoperative retention rate. RESULTS: The average age was 71.4 years (range 53-87). Urinary retention requiring catheterization was present in seven patients (78%). Two patients had a known diagnosis of prostate cancer preoperatively. The mean preoperative PSA on average was 21.6 ng/dL. Patients had a wide range of gland sizes, with a mean enucleated weight of 141 g (range 18-344 g). Mean reduction in hemoglobin was 16.9% following HoLEP. All patients managed to void postoperatively. All but one patient went home on postoperative day 1, and this patient went home on postoperative day 2. No patients required blood product transfusion or return to the operating room for clot irrigation postoperatively. CONCLUSION: HoLEP is a reasonable option for Jehovah's Witness and other patients with contraindications to blood product transfusion requiring surgical management of urinary symptoms due to enlarged prostate.

Stone-free Outcomes of Flexible Ureteroscopy for Renal Calculi Utilizing Computed Tomography Imaging.

OBJECTIVE: To assess stone-free rates following ureteroscopy (URS) for renal calculi at our institution using low-dose renal only computed tomography (CT). METHODS: A retrospective review of patients undergoing flexible URS for renal stones only with subsequent CT scan within 3 months. Meticulous basketing of all stone fragments was performed whenever possible. A "true" zero-fragment stone-free rate was determined by reviewing the CT scan and radiologist's report. Patients with nephrocalcinosis (as determined by visual inspection of papilla at the time of URS) were assigned the "stone-free" category. RESULTS: Flexible URS was performed in 288 renal units of 214 patients with renal calculi from 2013 to 2016. Median preoperative stone size was 6.2 mm with the average kidney containing 6.4 stones. An access sheath was used in 92% of cases. A total of 73% (209/288) renal units were completely stone free by CT assessment. Patients with residual fragments were as follows: 1 mm in 2% (7/288), 2-4 mm in 16% (46/288), and >4 mm in 9% of kidneys (26/288). CONCLUSION: The true stone-free rate in patients undergoing flexible URS for renal calculi utilizing active basketing of fragments as determined by strict CT assessment was 73%. In patients with residual fragments, the majority are 2-4 mm in size making URS a treatment option for renal calculi with excellent stone-free results.

A Survey of Morcellator Preference and Cost Comparison of the Lumenis VersaCut and Wolf Piranha Morcellators.

OBJECTIVE: To evaluate operating room (OR) costs associated with the 2 available morcellators in the United States in a matched cohort and to determine benign prostatic hyperplasia surgeon's morcellator preference. MATERIALS AND METHODS: Patients from 2013, the last year our institution exclusively used the VersaCut device, were matched 1:1 with the most recent patient cohort, utilizing the Wolf Piranha morcellator. Cost of morcellation including the expense of OR time and disposable instrument costs were calculated. A survey to the Endourological Society e-mail listserv was sent to determine morcellator preference. RESULTS: We identified 142 patients who underwent holmium laser enucleation of the prostate in 2013. When compared with the VersaCut group, morcellation efficiency (4.4 vs 7.0 g/min, P <.01) and expense of OR time ($1420.80 vs $992.21, P <.005) both favored the Piranha morcellator system even when the costs of disposable instruments were factored into the analysis ($1338.81 vs $1637.50, P <.05). A total of 126 urologists responded to the survey. Of these, 56 (44.5%) perform transurethral prostate enucleations, which included 48 (86%) holmium. More endourologists use the VersaCut (n = 33, 59%) than the Piranha (n = 24, 43%) morcellator. Qualities that impacted the preference of morcellator included the preferred device is safer, faster, easier to use, reusable, and less expensive. CONCLUSION: We identified a significant improved efficiency and improved cost savings utilizing the Piranha morcellator even when controlling for disposable costs. Of the endourologists who responded to the survey, less than half perform transurethral enucleation. Morcellator preference is largely based on safety, efficiency, and ease of use, whereas cost and reusablility were of lesser importance.

Accuracy of daily fluid intake measurements using a "smart" water bottle.

High fluid intake is an effective preventative strategy against recurrent kidney stones but is known to be challenging to achieve. Recently, a smart water bottle (Hidrate Spark™, Minneapolis, MN) was developed as a non-invasive fluid intake monitoring system. This device could help patients who form stones from low urine volume achieve sustainable improvements in hydration, but has yet to be validated in a clinical setting. Hidrate Spark™ uses capacitive touch sensing via an internal sensor. It calculates volume measurements by detecting changes in water level and sends data wirelessly to users' smartphones through an application. A pilot study was conducted to assess accuracy of measured fluid intake over 24 h periods when used in a real life setting. Subjects were provided smart bottles and given short tutorials on their use. Accuracy was determined by comparing 24-h fluid intake measurements calculated through the smart bottle via sensor to standard volume measurements calculated by the patient from hand over the same 24 h period. Eight subjects performed sixty-two 24-h measurements (range 4-14). Mean hand measurement was 57.2 oz/1692 mL (21-96 oz/621-2839 mL). Corresponding mean smart bottle measurement underestimated true fluid intake by 0.5 ozs. (95% CI -1.9, 0.9). Percent difference between hand and smart bottle measurements was 0.0% (95% CI - 3%, 3%). Intraclass correlation coefficient (ICC), calculated to assess consistency between hand measures and bottle measures, was 0.97 (0.95, 0.98) indicating an extremely high consistency between measures. 24-h fluid intake measurements from a novel fluid monitoring system (Hidrate Spark™) are accurate to within 3%. Such technology may be useful as a behavioral aide and/or research tool particularly among recurrent stone formers with low urinary volume.

Randomized Controlled Trial Comparing Three Different Modalities of Lithotrites for Intracorporeal Lithotripsy in Percutaneous Nephrolithotomy.

PURPOSE: To compare the efficiency (stone fragmentation and removal time) and complications of three models of intracorporeal lithotripters in percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: Prospective, randomized controlled trial at nine centers in North America from 2009 to 2016. Patients were randomized to one of three lithotripter devices: the Cyberwand, a dual-probe ultrasonic device; the Swiss Lithoclast Select, a combination pneumatic and ultrasonic device; and the StoneBreaker, a portable pneumatic device powered by CO2 cartridges. Since the StoneBreaker lacks an ultrasonic component, it was used with the LUS-II ultrasonic lithotripter to allow fair comparison with combination devices. RESULTS: Two hundred seventy patients were enrolled, 69 were excluded after randomization. Two hundred one patients completed the study: 71 in the Cyberwand group, 66 in the Lithoclast Select group, and 64 in the StoneBreaker group. The baseline patient characteristics of the three groups were similar. Mean stone surface area was smaller in the StoneBreaker group at 407.8 mm2 vs 577.5 mm2 (Lithoclast Select) and 627.9 mm2 (Cyberwand). The stone clearance rate was slowest in the StoneBreaker group at 24.0 mm2/min vs 28.9 mm2/min and 32.3 mm2/min in the Lithoclast Select and Cyberwand groups, respectively. After statistically adjusting for the smaller mean stone in the StoneBreaker group, there was no difference in the stone clearance rate among the three groups (p = 0.249). Secondary outcomes, including complications and stone-free rates, were similar between the groups. CONCLUSIONS: The Cyberwand, Lithoclast Select, and the StoneBreaker lithotripters have similar adjusted stone clearance rates in PCNL for stones >2 cm. The safety and efficacy of these devices are comparable.

Outcomes of Holmium Laser Enucleation of the Prostate in the Re-Treatment Setting.

PURPOSE: Holmium laser enucleation of the prostate can also be applied in the re-treatment setting when other benign prostatic hyperplasia therapies fail. We compared outcomes in men who underwent holmium laser enucleation of the prostate in the primary vs the re-treatment setting. MATERIALS AND METHODS: We retrospectively reviewed the records of 2,242 patients who underwent holmium laser enucleation of the prostate at a total of 4 academic hospitals between 2003 and 2015. Patient demographics, and operative and perioperative outcomes were compared between re-treatment and primary holmium laser enucleation of the prostate. RESULTS: Of the 360 of 2,242 men (16%) who underwent re-treatment holmium laser enucleation of the prostate the procedure was done for residual urinary symptoms in 71%. The most common primary procedure was transurethral resection of the prostate in 42% of cases. Mean time between prior benign prostatic hyperplasia surgery and re-treatment was 68 months (range 1 to 444). There were no significant differences in age, prostate size, AUA (American Urological Association) symptom score or average flow rate between the cohorts. Perioperatively, re-treatment holmium laser enucleation of the prostate was associated with significantly shorter operative time, reduced blood loss, lower specimen weight and shorter length of stay. The AUA symptom score improved in both groups, although it remained higher in men who underwent re-treatment (6.5 vs 5.0, p <0.001). The likelihood of clot retention (4.7% vs 1.8%, p = 0.01) and urethral stricture (3.3% vs 1.5%, p = 0.043) was slightly higher in the re-treatment group. CONCLUSIONS: Immediate perioperative outcomes of holmium laser enucleation of the prostate performed in the re-treatment setting were no different from those in the primary setting. While re-treatment was associated with an increased likelihood of clot retention, urethral stricture and higher AUA symptom score, these minimal differences must be considered against the overall favorable symptom improvement across both cohorts.

Comprehensive Costs Associated with Fiberoptic and Digital Flexible Ureteroscopes at a High Volume Teaching Hospital.

INTRODUCTION: Modern flexible ureteroscope ownership costs are considerable. Most prior estimates focus exclusively on repair costs, likely underestimating overall costs, including those of acquisition and reprocessing. Furthermore, to our knowledge no prior cost analyses focus on the latest generation digital flexible ureteroscope, which may differ due to unique purchase and repair prices. We sought to gain greater insight into the comprehensive costs associated with modern flexible ureteroscope use, particularly the difference between digital and fiberoptic models. METHODS: Data on use and repair of fiberoptic Storz Flex-X2 and digital Flex-Xc flexible ureteroscopes from 2011 to 2015 were reviewed. List prices and repair costs were obtained from Storz. Per case reprocessing costs were estimated, accounting for disposables, reagents and labor. Maintenance costs were estimated by combining cost of repairs and reprocessing. Analyses were performed at list pricing and standard discount rates. Global flexible ureteroscope costs were calculated to account for the cost of acquisition, repair and maintenance of a new scope during its first 100 uses. RESULTS: Global costs associated with digital flexible ureteroscope ownership were 1.3 to 1.4 times greater than fiberoptic on a per case basis ($1,008/$1,086 vs $715/$835). The majority of expenses went toward scope repairs (73% vs 71%), with instrument purchase (23% vs 24%) and reprocessing (4% vs 5%) being less costly. Repair rates were not significantly different between fiberoptic and digital devices (12.5 vs 11.5, p=0.757). CONCLUSIONS: Expenditures associated with ownership of modern flexible ureteroscopes are considerable and driven primarily by the high cost of repairs. Digital instruments are more costly despite comparable rates of flexible ureteroscope damage.

A Usability Comparison of Laser Suction Handpieces for Percutaneous Nephrolithotomy.

INTRODUCTION: The holmium laser has revolutionized the practice of minimally invasive endoscopy for kidney stones. Recently, a novel, rigid handpiece for use in percutaneous nephrolithotomy (PCNL) that couples the holmium laser with suction has been developed. To date, limited data exist regarding the usability and ergonomics of such treatment systems. We thus sought to compare surgeon-rated usability with three different suction laser handpieces in a porcine model. MATERIALS AND METHODS: We performed bilateral reverse PCNL on four female domestic farm pigs. After induction of general anesthesia, percutaneous access was obtained into each kidney by using biplanar fluoroscopy and 8 mm stones (plaster of Paris) were inserted into the calix or renal pelvis for treatment. Four surgeons tested the LASER Suction Tube (Karl Storz®, Germany), LithAssist™ (Cook® Medical), and Suction Handpiece (HP) (Lumenis®, Israel) by using a combination of fragmentation (5 Joules/20 Hertz) and dusting (0.8 Joules/80 Hertz) settings on the Lumenis pulse 120 H laser. The primary outcome assessed was the ease of use of the three devices as measured by a surgeon questionnaire. RESULTS: A total of 15 stones were treated in 8 renal units. The mean time required for stone fragmentation was 8 min. The mean handling and suction efficiency scores were similar between devices. The Suction HP offered the best laser fiber visibility during lithotripsy. CONCLUSION: Suction laser handpieces offer an option to treat renal stones via PCNL, with limited differences noted in most surgeon ratings between devices.

Percutaneous Nephrolithotomy in the Superobese: A Comparison of Outcomes Based on Body Mass Index.

INTRODUCTION: Percutaneous nephrolithotomy (PCNL) is considered the gold standard for treatment of large renal calculi. Although several investigators have examined the feasibility and outcomes associated with PCNL in obese patients, these studies have been limited by small sample size, lack of a comparator group, or few patients at body mass index (BMI) extremes. We thus compared outcomes of superobese (BMI >50) patients undergoing PCNL vs both an "overweight" and "ideal" cohort. METHODS: We used a prospectively maintained database to identify ideal (BMI 18.5-25), overweight (BMI 25.1-49.9), and superobese (BMI ≥50) patients who underwent PCNL. Our primary objective was to compare surgical outcomes between groups measured by the percent of patients who required secondary PCNL. We then compared complication rates, need for transfusion, and length of stay (LOS) using chi-square testing and ANOVA where appropriate. RESULTS: A total of 1152 patients were identified of which 254 were classified as ideal, 840 as overweight, and 58 as superobese. The overweight cohort had a higher mean age and greater proportion of males, whereas staghorn stones were more common in the superobese group. Comorbid conditions were more commonly observed in the superobese cohort. Otherwise, the groups were similar. Surgical outcomes were comparable with 47.2%, 42.0%, and 38.0% of ideal, overweight, and superobese patients requiring secondary PCNL (p = 0.25) with no difference in complication rates, need for transfusion, or LOS. CONCLUSION: PCNL can be effectively and safely performed in superobese patients with no difference in surgical outcomes or complications when compared to ideal or overweight patient cohorts.

Risks associated with drug treatments for kidney stones.

INTRODUCTION: Renal stones are one of the most painful medical conditions patients experience. For many they are also a recurrent problem. Fortunately, there are a number of drug therapies available to treat symptoms as well as prevent future stone formation. AREAS COVERED: Herein, we review the most common drugs used in the treatment of renal stones, explaining the mechanism of action and potential side effects. Search of the Medline databases and relevant textbooks was conducted to obtain the relevant information. Further details were sourced from drug prescribing manuals. Recent studies of drug effectiveness are included as appropriate. EXPERT OPINION: Recent controversies include medical expulsive therapy trials and complex role of urinary citrate in stone disease. Future directions in research will involve new medical therapies for stone prevention, for example new drugs for hyperoxaluria.

Transgluteal CT-Guided Percutaneous Renal Access for Percutaneous Nephrolithotomy in a Pelvic Horseshoe Kidney.

CT-guided percutaneous renal access has been described as a safe and effective access technique in patients with complex anatomy, including ectopic kidney, retrorenal colon, spinal dysraphism, hepatomegaly, and splenomegaly. In comparison to conventional intraoperative fluoroscopic-guided access, CT imaging allows for delineation of surrounding structures that are at risk for injury during percutaneous access. However, previous reports indicate that pelvic kidneys might be inaccessible percutaneously without laparoscopic assistance. Herein, we present a novel transgluteal route to renal access for percutaneous nephrolithotomy (PCNL) in a patient with a pelvic horseshoe kidney and severe spinal deformity.