Timing of Ureteral Stent Removal After Ureteroscopy on Stent-Related Symptoms: A Validated Questionnaire Comparison of 3 and 7 Days Stent Duration.

Objectives: To determine whether urinary symptoms are significantly improved with a shorter duration of stent placement without an increase in complications. Methods: A total of 100 patients were prospectively randomized to two groups, either a 3-day (n = 59, Group 1) or 7-day (n = 41, Group 2) stent placement group depending on date of operation. Patients submitted Ureteral Stent Symptom Questionnaires both while stents were in situ and 2 to 3 days after removal. Results: Group 2 reported greater urinary symptoms (p < 0.001) and pain (p < 0.001) with stents in situ compared with Group 1. Urinary symptoms (p < 0.001), pain (p = 0.003), and general health (p = 0.02) were more severe in Group 2 after stent removal as well. The analysis also revealed that urinary symptoms, pain, and general health improved after stent removal compared with stent in situ (p < 0.001). There were no significant differences in work-related functioning between two groups. There was one complication in Group 1 requiring bilateral stent replacement. There were no significant differences in emergency department visits, unplanned clinic visits, or hospitalizations between Groups 1 and 2. Conclusions: Patients with stent removal at 3-day group had better reported urinary, pain, and general health score compared with 7-day group. Patients after stent removal had improved urinary symptoms, pain symptom, and general health compared with ureteral stent in situ. There was no statistically significant difference in complications between the groups.

Mixed epithelial and stromal tumor of the kidney extending to the proximal ureter in a 41-year-old female.

We report the case of a 41-year-old pregnant female who presented with a complicated urinary tract infection. Further imaging revealed left hydronephrosis and filling defects extending from the proximal ureter to the upper pole of the kidney, with the presumed diagnosis of a fibroepithelial polyp. The patient underwent a four-stage percutaneous and ureteroscopic ablation and resection. Following the procedure, pathology instead confirmed the presence of a Mixed Epithelial and Stromal Tumor of the Kidney. For lesions that extend intraluminally into the ureters, a ureteroscopic and percutaneous resection can be considered as an alternative surgical approach.

Analgesic and Opioid Use for Patients Discharged from the Emergency Department with Ureteral Stones.

Objective: The aim of this study was to describe and characterize the analgesic and opioid use for patients discharged from the emergency department (ED) with renal colic due to ureteral stone. Methods: This is a secondary analysis of a multicenter prospective trial of ED patients diagnosed by CT scan as having a symptomatic ureteral stone <9 mm in diameter. Participants were contacted after randomization on days 2, 7, 15, 20, and 29 and reported opioid and nonopioid analgesic use and stone passage. CT scan was repeated on day 29 to 36 to confirm passage. Results: Of 403 participants, 314 (77.9%) took an analgesic after discharge and 199 (49.4%) took opioids. Opioids were more commonly used by younger patients (p = 0.04) and those with a family history of stones (p = 0.003). Stone size and tamsulosin use were not associated with analgesic utilization. Shorter time to passage and more distal stone location were associated with less analgesic and opioid use. For those who did not expel a stone, 55.0% took opioids at any time, and for those who did expel a stone, 31.9% took opioids before the stone was expelled and 15.7% took opioids at any time after the stone was expelled. Conclusions: Factors associated with increased use of analgesics in patients discharged from the ED include a longer time to stone passage, no spontaneous passage, and proximal position of the stone in the ureter. Some patients continued to use analgesics after the stone had passed, but most stopped using analgesics by day 29. The study has been registered at https://clinicaltrials.gov (NCT00382265).

Accuracy of Patient Reported Stone Passage for Patients With Acute Renal Colic Treated in the Emergency Department.

OBJECTIVE: To study patients who initially presented to the Emergency Department with acute renal colic to determine if patient-reported stone passage detects stone expulsion as accurately as follow-up computed tomography (CT) scan. METHODS: This is a secondary analysis of a multi-center prospective trial of patients diagnosed by a CT scan with a symptomatic ureteral stone <9 mm in diameter. Patient-reported stone passage, defined as capture or visualization of the stone, was compared to CT scan-confirmed passage performed 29-36 days after initial presentation. RESULTS: Four-hundred-three patients were randomized in the original study and 21 were excluded from this analysis because they were lost to follow-up or received ureteroscopic surgery. Of the 382 remaining evaluable patients, 237 (62.0%) underwent a follow-up CT scan. The mean (standard deviation) diameter of the symptomatic kidney stone was 3.8 mm (1.4). In those who reported stone passage, 93.8% (91/97) demonstrated passage of the symptomatic ureteral stone on follow-up CT. Of patients who did not report stone passage, 72.1% (101/140) demonstrated passage of their stone on follow-up CT. CONCLUSIONS: For patients who report capture or visualization of a ureteral stone, a follow-up CT scan may not be needed to verify stone passage. For patients who do not capture their stone or visualize stone passage, imaging should be considered to confirm passage.

Oxygen Venous Embolism After Hydrogen Peroxide Use During Percutaneous Nephrolithotomy.

Background: Hydrogen peroxide (H2O2) is a common antiseptic that is available without a prescription in the United States, and it is indicated for minor dermal abrasion; mouth, gum, or dental irritations; and removal of oral secretion. Several other medical uses have also been described, including clot dissolution during endoscopic gastrointestinal evaluation, cleansing of orthopedic surgical sites, and bladder irrigation. However, these uses of H2O2, as well as high-dose ingestion, have been associated with a wide variety of medical complications, including but not limited to air pulmonary embolism and stroke. Case Presentation: Our patient is a 51-year-old female with a medical history of hypertension, familial, hypercholesterolemia, gallstones, depression, coronary artery disease (identified on calcium study because of familial hypercholesterolemia), nephrolithiasis, and recurrent cystitis. She required percutaneous nephrolithotomy and had H2O2 administered for clot dissolution. The clinical and temporal evidence would suggest a transient pulmonary air embolus after the intrarenal administration of or irrigation with H2O2, large amounts under high pressure. Conclusion: This represents the first reported incidence of air embolus as a result of intrarenal administration of H2O2.

Are Emergently Placed Nephrostomy Tubes Suitable for Subsequent Percutaneous Endoscopic Renal Surgery?

OBJECTIVE: To determine the percentage of emergently placed nephrostomy tubes (NT) that were subsequently deemed usable for definitive percutaneous nephrolithotomy or percutaneous antegrade ureteroscopy in patients presenting with nephrolithiasis. METHODS: A multi-institutional retrospective database review was completed to identify patients who underwent emergent NT placement and then subsequent percutaneous nephrolithotomy or percutaneous antegrade ureteroscopy. Demographic, operative, and postoperative data were collected. Complications were classified using the Clavien-Dindo system. RESULTS: A total of 36 patients with 41 NTs met inclusion criteria. Indications for emergent NT placement were: obstruction with evidence of urinary tract infection/pyelonephritis (61%) and obstruction with acute kidney injury (39%). After recovery from the acute event and NT placement and during subsequent percutaneous surgical procedures, 9 NTs (22%) were sufficient without need for additional percutaneous access, 2 NTs (5%) were partially sufficient and were used in conjunction with an additional percutaneous access tract, and 30 NTs (73%) were unusable. CONCLUSION: In this multi-institutional review, only 22% of NTs placed for emergent indications were sufficient for subsequent percutaneous surgery without the creation of additional percutaneous tracts. Urologists should be prepared to obtain additional access during definitive percutaneous renal surgery in patients who have had a tube placed under emergent conditions.

Variation in Kidney Stone Composition Within the United States.

INTRODUCTION AND OBJECTIVES: Kidney stone incidence has been known to vary with temperature and climate. However, little is known about any variation in the composition of kidney stones across different regions of the United States. We attempted to evaluate whether stone composition changes depending on region. METHODS: We were given access to de-identified data from LABCORPs database of kidney stone composition from August 1, 2016, to October 24, 2016, for states in seven representative areas of the country: Virginia, Minnesota, Florida, Arizona, Colorado, California, and Texas. We analyzed each component of kidney stones with optical microscopy supplemented with Fourier-transform infrared spectroscopy (FT-IR) spectrometry using both the percentage of the stone that was composed of that component as well as a binary variable coded none vs any. Univariate associations between component and state were examined using chi-square or Fisher's exact test for the binary indicator, and analysis of variance for the continuous percentage. The same set of analyses was used for decade of age vs each component. The association between age and state was examined using analysis of variance. RESULTS: Data were available for 4335 kidney stones, from patients in the 7 states mentioned. The most common components across all stones were calcium oxalate monohydrate and calcium phosphate (both present in 93% of stones), calcium oxalate dihydrate (in 57% of stones), and uric acid (in 12% of stones). Stone composition did not vary widely across regions, except for uric acid stones, which were more prevalent in Florida compared to other states, with an odds ratio of 1.43 (95% confidence interval 1.12, 1.83). CONCLUSION: Kidney stone composition does not vary widely by region within the United States. Although temperature and humidity play a role in stone incidence, there does not appear to be a large variation between different climates, with the exception of uric acid stone formation in Florida.

Effect of Tamsulosin on Passage of Symptomatic Ureteral Stones: A Randomized Clinical Trial.

Importance: Urinary stone disease is a common presentation in the emergency department, and α-adrenergic receptor blockers, such as tamsulosin, are commonly used to facilitate stone passage. Objective: To determine if tamsulosin promotes the passage of urinary stones within 28 days among emergency department patients. Design, Setting, and Participants: We conducted a double-blind, placebo-controlled clinical trial from 2008 to 2009 (first phase) and then from 2012 to 2016 (second phase). Participants were followed for 90 days. The first phase was conducted at a single US emergency department; the second phase was conducted at 6 US emergency departments. Adult patients were eligible to participate if they presented with a symptomatic urinary stone in the ureter less than 9 mm in diameter, as demonstrated on computed tomography. Interventions: Participants were randomized to treatment with either tamsulosin, 0.4 mg, or matching placebo daily for 28 days. Main Outcomes and Measures: The primary outcome was stone passage based on visualization or capture by the study participant by day 28. Secondary outcomes included crossover to open-label tamsulosin, time to stone passage, return to work, use of analgesic medication, hospitalization, surgical intervention, and repeated emergency department visit for urinary stones. Results: The mean age of 512 participants randomized to tamsulosin or placebo was 40.6 years (range, 18-74 years), 139 (27.1%) were female, and 110 (22.8%) were nonwhite. The mean (SD) diameter of the urinary stones was 3.8 (1.4) mm. Four hundred ninety-seven patients were evaluated for the primary outcome. Stone passage rates were 50% in the tamsulosin group and 47% in the placebo group (relative risk, 1.05; 95.8% CI, 0.87-1.27; P = .60), a nonsignificant difference. None of the secondary outcomes were significantly different. All analyses were performed according to the intention-to-treat principle, although patients lost to follow-up before stone passage were excluded from the analysis of final outcome. Conclusions and Relevance: Tamsulosin did not significantly increase the stone passage rate compared with placebo. Our findings do not support the use of tamsulosin for symptomatic urinary stones smaller than 9 mm. Guidelines for medical expulsive therapy for urinary stones may need to be revised. Trial Registration: ClinicalTrials.gov Identifier: NCT00382265.

Contract Costs Associated with Maintaining Flexible Ureteroscopes: A Single Center Experience.

INTRODUCTION: We compared the cost of flexible ureteroscope processing and maintenance contracts offered by a scope manufacturer and a third-party company. METHODS: Use and repairs of the Storz 11278AU1 Flex X2 Flexible Ureteroscope are prospectively recorded at our large, 371-bed, acute care hospital. A retrospective analysis of the processing of ureteroscopic instruments during a 3-year period (2011 to 2013) was completed. We compared the handling of ureteroscopes between 1 year under a third-party contractor (Integrated Medical Systems International, Inc. [IMS]) and 2 prior years under the manufacturer (KARL STORZ) contract. RESULTS: From January 1, 2011 through October 1, 2012 our institution used the manufacturer for the processing of ureteroscopic instruments. From January 1, 2013 through December 9, 2013 our institution used the third-party contractor IMS for repairs. The number of procedures performed per repair/exchange during the manufacturer contract was 19.9 and the number of procedures performed per repair/exchange during the third-party contract was 11. The third-party contract resulted in a reduction of procedures performed per repair/exchange by 52%. Adjusted for inflation, the yearly cost of ureteroscope repairs was $125,715 during the manufacturer contract and $158,040 during the third-party contract. By analyzing the costs incurred in 2013, if our institution had maintained the manufacturer contract for all 3 years, the estimated repair cost would have resulted in a savings of $32,325. CONCLUSIONS: Using the manufacturer repair contract is more cost-effective than using that of third-party companies.

Osteitis pubis: A rare cause of suprapubic pain.

Osteitis pubis is a noninfectious inflammatory condition affecting the pubic symphysis. First described in a series of patients undergoing urologic procedures, it is an uncommon cause of lower abdominal and suprapubic pain. However, this condition can cause significant morbidity in patients affected, often requiring lengthy recovery periods. Given its rarity, the diagnosis and management is challenging, as many urologists are unfamiliar with the condition and may ascribe the constellation of symptoms as expected side effects from a recent surgical procedure. This review describes the urologic considerations for osteitis pubis, its potential etiologies, and clinical findings, and identifies treatment strategies for this potentially debilitating condition.

Metabolic Syndrome and Nephrolithiasis Risk: Should the Medical Management of Nephrolithiasis Include the Treatment of Metabolic Syndrome?

This article reviews the relationship between metabolic syndrome (MetS) and nephrolithiasis, as well as the clinical implications for patients with this dual diagnosis. MetS, estimated to affect 25% of adults in the United States, is associated with a fivefold increase in the risk of developing diabetes, a doubling of the risk of acquiring cardiovascular disease, and an increase in overall mortality. Defined as a syndrome, MetS is recognized clinically by numerous constitutive traits, including abdominal obesity, hypertension, dyslipidemia (elevated triglycerides, low high-density lipoprotein cholesterol), and hyperglycemia. Urologic complications of MetS include a 30% higher risk of nephrolithiasis, with an increased percentage of uric acid nephrolithiasis in the setting of hyperuricemia, hyperuricosuria, low urine pH, and low urinary volume. Current American Urological Association and European Association of Urology guidelines suggest investigating the etiology of nephrolithiasis in affected individuals; however, there is no specific goal of treating MetS as part of the medical management. Weight loss and exercise, the main lifestyle treatments of MetS, counter abdominal obesity and insulin resistance and reduce the incidence of cardiovascular events and the development of diabetes. These recommendations may offer a beneficial adjunctive treatment option for nephrolithiasis complicated by MetS. Although definitive therapeutic recommendations must await further studies, it seems both reasonable and justifiable for the urologist, as part of a multidisciplinary team, to recommend these important lifestyle changes to patients with both conditions. These recommendations should accompany the currently accepted management of nephrolithiasis.

A prospective, multi-institutional study of flexible ureteroscopy for proximal ureteral stones smaller than 2 cm.

PURPOSE: Flexible ureteroscopy is rapidly becoming a first line therapy for many patients with renal and ureteral stones. However, current understanding of treatment outcomes in patients with isolated proximal ureteral stones is limited. Therefore, we performed a prospective, multi-institutional study of ureteroscopic management of proximal ureteral stones smaller than 2 cm to better define clinical outcomes associated with this approach. MATERIALS AND METHODS: Adult patients with proximal ureteral calculi smaller than 2 cm were prospectively identified. Patients with concomitant ipsilateral renal calculi or prior ureteral stenting were excluded from study. Flexible ureteroscopy, holmium laser lithotripsy and ureteral stent placement was performed. Ureteral access sheath use, laser settings and other details of perioperative and postoperative management were based on individual surgeon preference. Stone clearance was determined by the results of renal ultrasound and plain x-ray of the kidneys, ureters and bladder 4 to 6 weeks postoperatively. RESULTS: Of 71 patients 44 (62%) were male and 27 (38%) were female. Mean age was 48.2 years. ASA(®) score was 1 in 12 cases (16%), 2 in 41 (58%), 3 in 16 (23%) and 4 in 2 (3%). Mean body mass index was 31.8 kg/m(2), mean stone size was 7.4 mm (range 5 to 15) and mean operative time was 60.3 minutes (range 15 to 148). Intraoperative complications occurred in 2 patients (2.8%), including mild ureteral trauma. Postoperative complications developed in 6 patients (8.7%), including urinary tract infection in 3, urinary retention in 2 and flash pulmonary edema in 1. The stone-free rate was 95% and for stones smaller than 1 cm it was 100%. CONCLUSIONS: Flexible ureteroscopy is associated with excellent clinical outcomes and acceptable morbidity when applied to patients with proximal ureteral stones smaller than 2 cm.

Fish oil supplementation and urinary oxalate excretion in normal subjects on a low-oxalate diet.

OBJECTIVE: To determine if fish oil supplementation reduces endogenous oxalate synthesis in healthy subjects. MATERIALS AND METHODS: Fifteen healthy non-stone-forming adults participated in this study. Subjects first abstained from using vitamins, medications, or foods enriched in omega-3 fatty acids for 30 days. Next, they collected two 24-hour urine specimens while consuming a self-selected diet. Subjects consumed an extremely low-oxalate and normal-calcium diet for 5 days and collected 24-hour urine specimens on the last 3 days of this diet. Next, the subjects took 2 fish oil capsules containing 650-mg eicosapentaenoic acid and 450-mg docosahexaenoic acid twice daily for 30 days. They consumed a self-selected diet on days 1-25 and the controlled diet on days 26-30. Twenty-four-hour urine samples were collected on days 28-30. Excretion levels of urinary analytes including oxalate and glycolate were analyzed. RESULTS: Although there was a significant reduction in urinary oxalate, magnesium, and potassium excretions and an increase in uric acid excretion during the controlled dietary phases compared with the self-selected diet, there were no significant differences in their excretion during controlled diet phases with and without fish oil supplementation. CONCLUSION: These results suggest that fish oil supplementation does not reduce endogenous oxalate synthesis or urinary oxalate excretion in normal adults during periods of extremely low oxalate intake. However, these results do not challenge the previously described reduction in urinary oxalate excretion demonstrated in normal subjects consuming a moderate amount of oxalate in conjunction with fish oil.

Does experience in creating a robot-assisted partial nephrectomy (RAPN) programme in an academic centre impact outcomes or complication rate?

OBJECTIVE: To evaluate the impact of increased experience in robot-assisted partial nephrectomy (RAPN) on perioperative and oncological outcomes To detail the complications encountered in establishing a RAPN programme at a tertiary referral centre and the factors associated with these complications. PATIENTS AND METHODS: The initial consecutive 233 patients undergoing RAPN between March 2008 and May 2012 at our institution were identified. Patients were divided into quartiles to evaluate outcomes, and uni- and multivariate predictors of complications were calculated. RESULTS: In progressive quartiles, patients tended to have more complex renal tumours as evaluated by R.E.N.A.L. nephrometry (P < 0.01) or preoperative aspects and dimensions used for an anatomical classification (PADUA) scores (P = 0.003), and percentage endophytic (P = 0.01). Developing technique increased the patients undergoing unclamped PN (P < 0.01). The mean time in the operating room (from skin incision to closure) decreased significantly from 225 to 183 min (P < 0.01) and warm ischaemia time decreased from 28 to 15 min, when clamping (P < 0.01). Clavien graded complication rate (P = 0.26) and positive margin rate (P = 0.32) was unchanged by quartile. CONCLUSION: We show that increasing experience allows more complex tumours to be removed with similar outcomes in patients undergoing RAPN. The complication rates and perioperative outcomes were similar in four successive quartiles of an initial experience of RAPN.

Changing stone composition profile of children with nephrolithiasis.

OBJECTIVE: To determine if this trend toward calcium phosphate stone formation exists in children. METHODS: This is a retrospective study of medical records of 179 children managed at our medical center from 1992-2010 for whom stone analysis and other pertinent laboratory data were available. A comparison of patients managed from 1992-2000 (P1) and 2001-2010 (P2) was undertaken. Statistical analysis included nonparametric tests. RESULTS: There were no significant differences in the mean age of the 2 cohorts. During both periods, boys comprised a significantly higher proportion during the first decade of life, whereas girls comprised a significantly higher proportion during the second decade. A higher percentage of patients had calcium oxalate (CaOx) stones in P1 compared to P2 (60% vs 47%, P = .0019). There was a significant increase in the percentage of patients having calcium phosphate stones in P2 compared to P1 (27% vs 18.5%, P = .008). Twenty-seven patients had recurrent stones. A comparison of the compositions of the first and last stones of patients within this group demonstrated an increasing proportion of brushite stones (3.7% vs 11.1%, P = .04). Twenty-four hour urine testing results were similar for those with CaOx and calcium phosphate stones. CONCLUSION: An increasing proportion of children have calcium phosphate calculi. Brushite stones are more prevalent in children with recurrent stone events. The impetus of these shifts is not readily apparent.

Comparison of clamping technique in robotic partial nephrectomy: does unclamped partial nephrectomy improve perioperative outcomes and renal function?

INTRODUCTION: Partial nephrectomy without renal vascular occlusion has been introduced to improve outcomes in patients undergoing robotic partial nephrectomy (RPN). We prospectively evaluated unclamped RPN at our institution and compared this to other clamping techniques in a non-randomized fashion. MATERIALS AND METHODS: Ninety-five consecutive patients who successfully completed RPN between June 2010 and October 2011 are included in this analysis. All RPNs were performed by a single surgeon. Clamping technique was artery and vein (AV), artery alone (AO) or unclamped (U) without hypotensive anesthesia. Clamping decision was based on surgeon preference and feasibility of minimizing ischemia. All patients had bilateral functional renal units. RESULTS: Eighteen (19%), 58 (61%) and 19 (20%) patients had AV, AO and U technique respectively. Preoperative characteristics including age (p = 0.43), body mass index (p = 0.40) and RENAL nephromety distribution (p = 0.10) were similar. In AV and AO, mean warm ischemia time were 19 and 17 minutes and similar between the two cohorts (p = 0.39). Mean glomerular filtration rate (GFR) and overall percentage decrease in GFR at time of at last follow up were (64, 69, 81, p = 0.12) and (6%, 6%,and 2%,p = 0.79) for AV, AO and U respectively. Median follow up for last serum creatinine was 113 days and was similar between all cohorts (p = 0.37). Complication rate (p = 0.37), positive margin rate (p = 0.84), and change in hemoglobin concentration postoperatively (p = 0.94) were similar between cohorts. CONCLUSIONS: Unclamped partial nephrectomy is possible in patients undergoing RPN. In this study, it does not significantly alter perioperative or postoperative renal function or change rate of complications. Minimal ischemia, irrespective of clamping technique, in patients with bilateral renal units does not appear to adversely effect intermediate term renal function in these patients.

The effects of Oxazyme on oxalate degradation: results and implications of in vitro experiments.

UNLABELLED: Abstract Background and Purpose: Urinary oxalate excretion influences the development of calcium oxalate kidney stones. Urinary oxalate is derived from dietary sources and endogenous synthesis. Oxalate decarboxylase metabolizes oxalate and, if consumed, could theoretically accomplish this in the gastrointestinal tract. This study aimed to determine whether a commercially produced form of oxalate decarboxylase (Oxazyme(®)) could degrade oxalate in simulated gastric and intestinal environments. MATERIALS AND METHODS: One buffer (pH 3.6) simulated the gastric environment, while another (pH 6.5), approximated the proximal intestine. Potassium oxalate (soluble form of oxalate) and whole and homogenized spinach (a high oxalate containing food) were incubated in the different buffered solutions, with or without Oxazyme. Oxalate content, after incubation, was measured using established ion chromatographic techniques. RESULTS: Oxazyme resulted in complete degradation of oxalate derived from potassium oxalate in the intestinal buffer; meanwhile, oxalate derived from potassium oxalate in the gastric buffer was profoundly digested by Oxazyme. Adding Oxazyme also substantially reduced the oxalate content of both whole and homogenized spinach preparations, in either buffer. CONCLUSIONS: These in vitro findings demonstrate that Oxazyme can metabolize oxalate in both simulated gastric and small intestinal environments.

Safety and efficacy of removable inferior vena cava filters in anticoagulated patients undergoing percutaneous nephrostolithotomy.

BACKGROUND AND PURPOSE: Increasing numbers of patients are receiving a diagnosis of thrombophilic conditions necessitating chronic anticoagulation therapy. The best management approach for such patients needing percutaneous nephrostolithotomy (PCNL) has not been established. Discontinuing anticoagulation therapy before PCNL is needed to prevent hemorrhage, placing some of these patients at risk for thromboembolic events. We describe the use of removable inferior vena cava filters (RIVCF) in patients undergoing PCNL who are at risk for a venous thromboembolic event. PATIENTS AND METHODS: A retrospective study of outcomes of PCNL with RIVCF placement was conducted. RESULTS: Four patients underwent PCNL with RIVCF placement on the same day of the procedure. The mean age was 49 years (range 35-69 years). PCNL was performed on a total of six renal units with a mean of 2.2 (range 1-3) operations per renal unit. Five of six (83%) renal units were rendered stone free. There were no complications associated with either the PCNL or RIVCF placement. No patient had a thromboembolic event or received blood products. Two of the four patients underwent successful removal of the RIVCF, and one elected to keep the device in place. The device could not be extracted in the other patient. The average length that the filters were in place was 52.5 days. Patients resumed anticoagulation therapy shortly after RIVCF removal. CONCLUSION: RIVCF placement is a safe and effective method of preventing venous thromboembolic complications in thrombophilic patients needing PCNL. Patients should be informed, however, that RIVCF removal is not always possible.

Gas-containing renal stones: findings from five consecutive patients.

OBJECTIVE: To describe the clinical course, microbiology, and metabolic findings of 5 patients presenting to our institution with gas-containing renal stones. MATERIALS AND METHODS: During a 20-month period beginning in 2009, 5 patients were identified by computed tomography scanning to harbor gas-containing renal calculi. Despite similar imaging and referral practice patterns, no such cases had been seen at our institution in the preceding 20 years. The records of these patients were reviewed to better characterize this unique condition. RESULTS: All 5 subjects were premenopausal women. One patient presented with urosepsis and 4 presented with flank pain. All had urinary tract infections, and Escherichia coli was isolated from a voided urine specimen in 3. Stone culture was positive in 2 and was concordant with the voided specimen in 1. The stones were solitary in 4 and multiple in 1 patient. All the stones were composed of calcium phosphate. Of the 5 patients, 3 had pure calcium phosphate stones and 2 had stones with calcium oxalate monohydrate components. Also, 3 subjects had diabetes mellitus, 3 had hypertension, and 1 had a history of gout. Two subjects underwent 24-hour urine metabolic testing, and abnormalities were identified in both. All patients were rendered stone free: 4 with percutaneous nephrostolithotomy and 1 using robotic pyelolithotomy. CONCLUSION: Gas-containing renal stones are rare but might be increasing in prevalence. The pathophysiology is unknown but is most likely influenced by a combination of metabolic and infectious factors.