Paravertebral block for percutaneous nephrolithotomy: a prospective, randomized, double-blind placebo-controlled study.

PURPOSE: Percutaneous nephrolithotomy (PCNL) is performed commonly in patients with large kidney stones, but the management of their postoperative pain presents a major challenge. While it is not routinely performed in PCNL patients, paravertebral block (PVB) has been described as an effective strategy for pain control after various non-urologic surgeries. This trial aims to assess the effect of paravertebral blockade on intraoperative and postoperative opioid use as well as postoperative pain control in patients undergoing PCNL. METHODS: This was a prospective, randomized, double-blind, placebo-controlled study. Patients who consented to participate were randomly assigned to undergo either PVB or a placebo intervention preoperatively. The patient, surgeon, and anesthesia team were all blinded to the randomization. The outcome parameters were intraoperative opioid requirement, postoperative visual analog scale (VAS) pain scores, postoperative opioid use, and postoperative antiemetic use. RESULTS: 23 patients were enrolled in each arm of the study, and the two groups had no significant differences in baseline demographic or clinical characteristics. Patients in the PVB group had significantly lower intraoperative opioid use, postoperative opioid use, frequency of opioid use, and antiemetic. Patients in the PVB group also had lower postoperative VAS pain scores. There were no patients who suffered from complications attributable to PVB. CONCLUSION: The results of this randomized, double-blind, placebo-controlled trial suggest that PVB should be considered an effective strategy to reduce opioid requirement and improve pain control for patients undergoing PCNL.

Complications of Recognized and Unrecognized Iatrogenic Ureteral Injury at Time of Hysterectomy: A Population Based Analysis.

PURPOSE: Ureteral injury represents an uncommon but potentially morbid surgical complication. We sought to characterize the complications of iatrogenic ureteral injury and assess the effect of recognized vs delayed recognition on patient outcomes. MATERIALS AND METHODS: Patients who underwent hysterectomy were identified in the Healthcare Cost and Utilization Project California State Inpatient Database for 2007 to 2011. Ureteral injuries were identified and categorized as recognized-diagnosed/repaired on the day of hysterectomy and unrecognized-diagnosed/repaired postoperatively. We assessed the outcomes of 90-day hospital readmission as well as 1-year outcomes of nephrostomy tube placement, urinary fistula, acute renal failure, sepsis and overall mortality. The independent effects of recognized and unrecognized ureteral injuries were determined on multivariate analysis. RESULTS: Ureteral injury occurred in 1,753 of 223,872 patients (0.78%) treated with hysterectomy and it was unrecognized in 1,094 (62.4%). The 90-day readmission rate increased from a baseline of 5.7% to 13.4% and 67.3% after recognized and unrecognized injury, respectively. Nephrostomy tubes were required in 2.3% of recognized and 23.4% of unrecognized ureteral injury cases. Recognized and unrecognized ureteral injuries independently increased the risk of sepsis (aOR 2.0, 95% CI 1.2-3.5 and 11.9, 95% CI 9.9-14.3) and urinary fistula (aOR 5.9, 95% CI 2.2-16 and 124, 95% CI 95.7-160, respectively). During followup unrecognized ureteral injury increased the odds of acute renal insufficiency (aOR 23.8, 95% CI 20.1-28.2) and death (1.4, 95% CI 1.03-1.9, p = 0032). CONCLUSIONS: Iatrogenic ureteral injury increases the risk of hospital readmission and significant, potentially life threatening complications. Unrecognized ureteral injury markedly increases these risks, warranting a high level of suspicion for ureteral injury and a low threshold for diagnostic investigation.

Postoperative Urinary Retention is an Independent Predictor of Short-Term and Long-Term Future Bladder Outlet Procedure in Men.

PURPOSE: Postoperative urinary retention is a common complication across surgical specialties. To our knowledge no literature to date has examined postoperative urinary retention as a predictor of long-term receipt of surgery for bladder outlet obstruction. MATERIALS AND METHODS: We retrospectively reviewed the records of inpatients who underwent nonurological surgery in California between 2008 and 2010. Postoperative urinary retention during the index admission was identified, as was receipt of a bladder outlet procedure (transurethral prostate resection, prostate photoselective vaporization or suprapubic prostatectomy) at a subsequent encounter. Patients were matched using propensity scoring of demographics, comorbidities and surgery type. Adjusted Kaplan-Meier analysis was performed to determine the cumulative incidence of subsequent bladder outlet procedures by patient group, including group 1-age 60 years or greater and postoperative urinary retention, group 2-age 60 years or greater and no postoperative urinary retention, group 3-age less than 60 years and postoperative urinary retention, and group 4-age less than 60 years and no postoperative urinary retention. RESULTS: Of 769,141 eligible male patients postoperative urinary retention developed in 8,051 (1.1%). Following hospital discharge 1,855 patients (0.24%) underwent a bladder outlet procedure. Those treated with a bladder outlet procedure were significantly more likely to have experienced postoperative urinary retention during the index admission (6.3% vs 1.0%, p <0.001). On matched analysis the bladder outlet procedure rate at 3 years was 7.1%, 2.2%, 0.8% and 0.0% in groups 1, 2, 3 and 4, respectively. CONCLUSIONS: In men 60 years old or older postoperative urinary retention identified those with an increased incidence of bladder outlet procedures within 3 years. Men younger than 60 years had a low rate of subsequent bladder outlet procedures regardless of a postoperative urinary retention diagnosis.

New modalities for evaluation and surveillance of complex renal cysts.

PURPOSE: The increased use of abdominal imaging has led to more frequent detection of incidental renal cysts. Since the inception of the Bosniak classification system, management of Bosniak I, III and IV cysts has been clearly defined, while evaluation and management of Bosniak II and IIF cysts have remained a clinical dilemma. Discussions of new imaging modalities are becoming increasingly prevalent in the radiological literature. In this context we performed a comprehensive review of the recent literature on complex renal cysts focusing on new imaging modalities, surveillance strategies and biopsy. MATERIALS AND METHODS: We performed a comprehensive literature review of articles published from January 1, 1998 through December 31, 2013 via MEDLINE(®), EMBASE and the Cochrane Collection using a predetermined search strategy. All studies included were performed in humans older than 18 years, were written in English and had an abstract available for review. We grouped studies into 1 of 5 categories, ie computerized tomography, magnetic resonance imaging, ultrasound, biopsy and surveillance. RESULTS: While computerized tomography and magnetic resonance imaging with and without contrast enhancement remain the gold standard to evaluate cystic lesions of the kidney, diffusion-weighted magnetic resonance imaging and contrast enhanced ultrasound have surfaced as new tools for assessment of complex cysts. Comparative effectiveness studies on these new imaging modalities are limited. Image guided biopsy has increasingly been shown to be useful for evaluation of intermediate (Bosniak II and IIF) complex cysts. We found few studies providing guidance on the duration and/or intensity of surveillance required for intermediate complex renal cysts. CONCLUSIONS: Although new and enhanced techniques are in development and may be useful in the future management of complex renal cysts, there is a paucity of data regarding the value of these new techniques. Future research should focus on surveillance of intermediate complex renal cysts, particularly on the ideal frequency and type of imaging required.

Medical management of kidney stones: AUA guideline.

PURPOSE: The purpose of this guideline is to provide a clinical framework for the diagnosis, prevention and follow-up of adult patients with kidney stones based on the best available published literature. MATERIALS AND METHODS: The primary source of evidence for this guideline was the systematic review conducted by the Agency for Healthcare Research and Quality on recurrent nephrolithiasis in adults. To augment and broaden the body of evidence in the AHRQ report, the AUA conducted supplementary searches for articles published from 2007 through 2012 that were systematically reviewed using a methodology developed a priori. In total, these sources yielded 46 studies that were used to form evidence-based guideline statements. In the absence of sufficient evidence, additional statements were developed as Clinical Principles and Expert Opinions. RESULTS: Guideline statements were created to inform clinicians regarding the use of a screening evaluation for first-time and recurrent stone formers, the appropriate initiation of a metabolic evaluation in select patients and recommendations for the initiation and follow-up of medication and/or dietary measures in specific patients. CONCLUSIONS: A variety of medications and dietary measures have been evaluated with greater or less rigor for their efficacy in reducing recurrence rates in stone formers. The guideline statements offered in this document provide a simple, evidence-based approach to identify high-risk or interested stone-forming patients for whom medical and dietary therapy based on metabolic testing and close follow-up is likely to be effective in reducing stone recurrence.

Bilateral urinary calculi with discordant stone composition.

OBJECTIVES: To describe a cohort of bilateral stone formers with significantly different compositions between renal units. METHODS: Patients treated for bilateral nephrolithiasis over a 4-year period (2007-2010) were identified. Stones were categorized by dominant (≥50%) mineralogical component. Patients with significant compositional differences between renal units (discordant stone formers) were compared to patients with a similar stone type in each kidney. RESULTS: Fifteen of the 59 bilateral stone formers (25.4%) were discordant stone formers with significant differences in stone composition between renal units. Forty-four of the 59 patients (74.6%) had the same stone composition on each side. Thirty percent of discordant stones had calcium phosphate as the dominant stone component. Discordant stone formers were younger, had better renal function, and tended to have a larger stone burden (p < 0.05). CONCLUSIONS: A significant minority of bilateral stone formers form a different type of stone in each kidney. Local or micro-environmental etiologies may explain this phenomenon and may also account for failure of preventive therapy in some patients.

Comparison of Work Relative Value Units Assigned to Urological and Gynecological Surgical Procedures.

INTRODUCTION: We sought to determine if work relative value unit differences exist between analogous, sex-specific procedures. METHODS: Representatives from the AUA and the American College of Obstetricians and Gynecologists independently reviewed the entire procedural code set and identified sex-specific procedures that had an analogous procedure in the opposite sex. These pairs were then evaluated and compared using current American Medical Association Relative Value Scale Update Committee methodology. Comparable code pair values were then examined to determine any systemic bias in the work relative value units assigned between the procedures. Mean differences and 95% confidence intervals were used to determine any differences in procedure or physician time values. The methodology used considered global period, intraservice time, total time, hospital days, postoperative office visits, and the date of the committee review. RESULTS: Of the 10 directly analogous code pairs reviewed, 7 of the female procedures had higher work relative value unit differences (range 0.29-6.47), and 3 of the male procedures had higher work relative value unit differences (range 1.23-2.34). There was no statistical difference between the code pair work relative value units. The work relative value unit per minute of intraservice time and total time were not statistically different. CONCLUSIONS: In this study, we compared operative procedures performed in women with clinically comparable operative procedures performed in men that had similar surgical approaches, global periods, and valuation methodologies. Overall, no statistical differences in work relative value units were demonstrated.

Localized Urinary Bladder Amyloidosis as Urothelial Cancer Mimicker.

CONTEXT.­: Localized amyloidosis of the bladder is rare and often mimics bladder malignancy. It is typically associated with the extracellular deposition of monoclonal light chains, either κ or λ. The cause is unknown, but it is thought to be due to chronic inflammation/cystitis. OBJECTIVE.­: To highlight the importance of localized urinary bladder amyloidosis as a rare mimicker of urothelial malignancy and elucidate its clinical, histopathologic, and cytopathologic manifestations. DESIGN.­: Cases of urinary bladder amyloidosis diagnosed during 2000-2023 were retrieved retrospectively from pathology archives. Electronic medical records, including cystoscopy findings and pathology slides including Congo red stain, were reviewed. RESULTS.­: Here we present 6 patients with localized urinary bladder amyloidosis. Four of the 6 patients were women, with ages ranging from 46 to 69 years, and a mean age of 58 years. Five of 6 patients presented with hematuria, while in 1 patient, bladder amyloidosis was discovered incidentally. Cystoscopy findings invariably were concerning for malignancy, with raised erythema in 5 patients and fungating mass protruding into the bladder lumen in 1 patient. Bladder biopsies and urine cytology were negative for malignancy in all cases. Congo red-positive amyloid deposits involved lamina propria with sparing of the detrusor muscle. In 5 cases, the deposits were typed as derived from the λ light chain, whereas no information was available for 1 patient. Subsequent clinical workup ruled out systemic amyloidosis. CONCLUSIONS.­: These cases of urinary bladder amyloidosis highlight the importance of considering rare amyloidosis in the differential diagnosis of hematuria and cystoscopy with a lesion mimicking malignancy.

Metabolic syndrome and the urinary microbiome of patients undergoing percutaneous nephrolithotomy.

Objective: To identify possible stone-promoting microbes, we compared the profiles of microbes grown from stones of patients with and without metabolic syndrome (MetS). The association between MetS and urinary stone disease is well established, but the exact pathophysiologic relationship remains unknown. Recent evidence suggests urinary tract dysbiosis may lead to increased nephrolithiasis risk. Methods: At the time of percutaneous nephrolithotomy, bladder urine and stone fragments were collected from patients with and without MetS. Both sample types were subjected to expanded quantitative urine culture (EQUC) and 16 S ribosomal RNA gene sequencing. Results: Fifty-seven patients included 12 controls (21.1%) and 45 MetS patients (78.9%). Both cohorts were similar with respect to demographics and non-MetS comorbidities. No controls had uric acid stone composition. By EQUC, bacteria were detected more frequently in MetS stones (42.2%) compared to controls (8.3%) (p=0.041). Bacteria also were more abundant in stones of MetS patients compared to controls. To validate our EQUC results, we performed 16 S ribosomal RNA gene sequencing. In 12/16 (75.0%) sequence-positive stones, EQUC reliably isolated at least one species of the sequenced genera. Bacteria were detected in both "infectious" and "non-infectious" stone compositions. Conclusion: Bacteria are more common and more abundant in MetS stones than control stones. Our findings support a role for bacteria in urinary stone disease for patients with MetS regardless of stone composition.

Variability in prostate cancer detection among radiologists and urologists using MRI fusion biopsy.

Objectives: The aim of this study is to evaluate the impact of radiologist and urologist variability on detection of prostate cancer (PCa) and clinically significant prostate cancer (csPCa) with magnetic resonance imaging (MRI)-transrectal ultrasound (TRUS) fusion prostate biopsies. Patients and methods: The Prospective Loyola University MRI (PLUM) Prostate Biopsy Cohort (January 2015 to December 2020) was used to identify men receiving their first MRI and MRI/TRUS fusion biopsy for suspected PCa. Clinical, MRI and biopsy data were stratified by radiologist and urologist to evaluate variation in Prostate Imaging-Reporting and Data System (PI-RADS) grading, lesion number and cancer detection. Multivariable logistic regression (MVR) models and area under the curve (AUC) comparisons assessed the relative impact of individual radiologists and urologists. Results: A total of 865 patients (469 biopsy-naïve) were included across 5 urologists and 10 radiologists. Radiologists varied with grading 15.4% to 44.8% of patients with MRI lesions as PI-RADS 3. PCa detection varied significantly by radiologist, from 34.5% to 66.7% (p = 0.003) for PCa and 17.2% to 50% (p = 0.001) for csPCa. Urologists' PCa diagnosis rates varied between 29.2% and 55.8% (p = 0.013) and between 24.6% and 39.8% (p = 0.36) for csPCa. After adjustment for case-mix on MVR, a fourfold to fivefold difference in PCa detection was observed between the highest-performing and lowest-performing radiologist (OR 0.22, 95%CI 0.10-0.47, p < 0.001). MVR demonstrated improved AUC for any PCa and csPCa detection when controlling for radiologist variation (p = 0.017 and p = 0.038), but controlling for urologist was not significant (p = 0.22 and p = 0.086). Any PCa detection (OR 1.64, 95%CI 1.06-2.55, p = 0.03) and csPCa detection (OR 1.57, 95%CI 1.00-2.48, p = 0.05) improved over time (2018-2020 vs. 2015-2017). Conclusions: Variability among radiologists in PI-RADS grading is a key area for quality improvement significantly impacting the detection of PCa and csPCa. Variability for performance of MRI-TRUS fusion prostate biopsies exists by urologist but with less impact on overall detection of csPCa.

Five-year experience with metallic stents for chronic ureteral obstruction.

PURPOSE: We present 5 years of outcome data on metallic ureteral stents in a cohort of patients treated for chronic ureteral obstruction. MATERIALS AND METHODS: We retrospectively identified and analyzed the records of all patients in whom a Resonance® Metallic Ureteral Stent was placed between early 2007 and late 2011 at our institution. We performed a descriptive analysis of key outcomes, including the failure and death rates, and stenting duration, defined as the time from initial stent placement to last stent failure or patient death. We also performed a secondary comparative analysis of patients with a benign vs malignant etiology of obstruction. RESULTS: A total of 139 metallic stents were placed in 47 patients, including 27 (57%) with malignant and 20 (43%) with a benign etiology. Of the patients 15 (32%) had bilateral obstruction. Maximum followup was 59 months (mean 20, median 13, IQR 4-31). Stent failure occurred in 13 patients (28%), including 4 in the benign and 9 in the malignant group (p = 0.35). The median duration of stenting for benign and malignant obstruction was 22 (IQR 9-39) vs 7 months (IQR 3-25) (p = 0.106). Stenting duration was equivalent when controlling for the higher death rate in the malignant group. CONCLUSIONS: Resonance metallic stents are an adequate management strategy for benign and malignant ureteral obstruction. A subset of patients in each group continued to do well at more than a 3-year overall duration of stenting. Failure rates were similar for benign and malignant etiologies.

Comparison of complication rates for unilateral and bilateral percutaneous nephrolithotomy (PCNL) using a modified Clavien grading system.

OBJECTIVE: To compare complication rates of unilateral vs bilateral percutaneous nephrolithotomy (PCNL) using the modified Clavien grading system. PATIENTS AND METHODS: Single-institution retrospective chart review. Identified patients who had synchronous bilateral PCNL (B-PCNL) over an 11-year period (2000-2011). B-PCNL patients were matched by age, gender, and stone burden per renal unit with patients who underwent unilateral PCNL (U-PCNL) over the same period. Complications were recorded and classified using the modified Clavien classification system, and then compared with a two-sided chi-square test of proportions. RESULTS: In all, 47 B-PCNL patients [mean (range) age 54 (14-84) years] and 78 U-PCNL patients [mean (range) age 54 (17-91 years] were compared. The mean (range) stone burden per renal unit was 2.8 (0.7-7.0) cm and 2.9 (0.7-9.0) cm, respectively. The overall complication rate was higher for B-PCNL (53.2% vs 30.8%, P = 0.013). Rates of Grade I and Grade II complications trended toward being higher in the B-PCNL group. Low-grade complications (Grade I and II combined) occurred more often in the B-PCNL group (P = 0.011); the most common low-grade complication was fever. Two procedures terminated for poor visualisation due to bleeding were successfully completed in delayed fashion with no transfusion and were classified as Grade I complications. There were equivalently low rates of Grade III complications. There were no Grade IV or V complications. CONCLUSIONS: B-PCNL carries a higher overall complication rate than U-PCNL when the modified Clavien system is used for classification. Patients undergoing U-PCNL who have more than one tract dilatation have a higher complication rate than those who have only one tract dilatation. High-grade complications are uncommon for both procedures.

Update on the evaluation of repeated stone formers.

Office management of stone disease is an important component of a urologist's practice. Evaluation should include analysis of stone composition, 24-hour urine studies, identification of modifiable risk factors, and targeted dietary, lifestyle, and/or medical therapy. A sizeable portion of investigated etiologies and risk factors for stone disease have centered on the complex interplay between obesity, diabetes, and other disease states that comprise the metabolic syndrome. Alternatives to traditional preventive therapy, such as probiotics and various fruit juices, are still being studied but may prove useful adjuncts to traditional preventive therapy, where the mainstays remain increased fluid intake, dietary modification, and pharmacologic therapy. Future studies on preventive therapy of urolithiasis are likely to focus on strategies to increase compliance, cost-effectiveness, and systems-based implementation.

Diagnosis, evaluation and follow-up of asymptomatic microhematuria (AMH) in adults: AUA guideline.

PURPOSE: The purpose of this guideline is to provide a clinical framework for the diagnosis, evaluation and follow-up of asymptomatic microhematuria. MATERIALS AND METHODS: A systematic literature review using the MEDLINE® database was conducted to identify peer reviewed publications relevant to the definition, diagnosis, evaluation and follow-up for AMH. The review yielded 191 evidence-based articles, and these publications were used to create the majority of the guideline statements. There was insufficient evidence-based data for certain concepts; therefore, clinical principles and consensus expert opinions were used for portions of the guideline statements. RESULTS: Guideline statements are provided for diagnosis, evaluation and follow-up. The panel identified multiphasic computed tomography as the preferred imaging technique and developed guideline statements for persistent or recurrent AMH as well as follow-up. CONCLUSIONS: AMH is only diagnosed by microscopy; a dipstick reading suggestive of hematuria should not lead to imaging or further investigation without confirmation of three or greater red blood cells per high power field. The evaluation and follow-up algorithm and guidelines provide a systematic approach to the patient with AMH. All patients 35 years or older should undergo cystoscopy, and upper urinary tract imaging is indicated in all adults with AMH in the absence of known benign causation. The imaging modalities and physical evaluation techniques are evolving, and these guidelines will need to be updated as the effectiveness of these become available. Please visit the AUA website at http://www.auanet.org/content/media/asymptomatic_microhematuria_guideline.pdf to view this guideline in its entirety.

Using Intraoperative Portable CT Scan to Minimize Reintervention Rates in Percutaneous Nephrolithotomy: A Prospective Trial.

Background and Purpose: More than 40% of patients undergoing percutaneous nephrolithotomy (PCNL) are left with residual stone fragments and often require secondary procedures. Portable CT (PCT) technology allows surgeons to obtain intraoperative cross-sectional imaging, identify and extract residual stones immediately, and thereby reduce the need for subsequent procedures. This prospective trial evaluates how incorporation of PCT during PCNL affects perioperative outcomes. Patients and Methods: We prospectively enrolled eligible patients undergoing initial PCNL for this trial (n = 60), which entailed a single intraoperative CT abdomen and ipsilateral antegrade ureteroscopy when the surgeon felt stone treatment was visually complete. If residual fragments were identified, the surgeon continued nephroscopy to find and remove them; if not, the procedure was concluded. These patients were compared with a retrospective cohort (n = 174) who underwent initial PCNL with postoperative imaging performed the following day. Results: The two cohorts had similar demographic properties and stone characteristics, and location of percutaneous access. In the prospective arm, 50% of intraoperative PCT scans identified residual fragments, prompting continuation of surgery to remove them. This cohort had significantly higher stone-free rate (82% vs 36%, p < 0.01), lower rate of planned reintervention (7% vs 32%, p < 0.01), lower rate of urgent presentation with ureteral obstruction (0% vs 7%, p = 0.04), lower total CT-based effective radiation dose (8.4 mSv vs 14.6 mSv, p < 0.01), and shorter length of stay (2.3 days vs 3.5 days, p < 0.01) when compared with the retrospective cohort that did not use intraoperative PCT. Conclusions: Obtaining an intraoperative PCT scan during PCNL can substantially improve perioperative outcomes. Further evaluation of this modality through a randomized controlled trial is warranted. Clinical Trial Registration Number: NCT04556396.

Paclitaxel inhibits ureteral smooth muscle cell proliferation and collagen production in the absence of cell toxicity.

PURPOSE: Urinary tract stricture results from excess collagen deposition at an injured area. Paclitaxel (Sigma-Aldrich®) prevents coronary artery restenosis by inhibiting vascular smooth muscle cell proliferation and collagen production. We evaluated the effects of paclitaxel on ureteral smooth muscle cell proliferation and collagen production. MATERIALS AND METHODS: Three phases of experiments were done in canine smooth muscle cells. In phase 1 we used proliferation assay to study smooth muscle cells exposed to various concentrations of paclitaxel during 7 days. Phase 2 consisted of 6-day enzyme-linked immunosorbent assay to detect the total amount of type III collagen produced by smooth muscle cells exposed to paclitaxel. In phase 3 we assessed smooth muscle cell membrane damage using a lactate dehydrogenase cytotoxicity assay in which cells were exposed to escalating paclitaxel concentrations for 14 days. RESULTS: Proliferation studies showed that 10 and 100 nM paclitaxel significantly inhibited ureteral smooth muscle cell proliferation. Enzyme-linked immunosorbent assay revealed significantly decreased type III collagen production at 100 nM. Cytotoxicity testing showed that 1 to 100 nM paclitaxel did not harm smooth muscle cells. CONCLUSIONS: Paclitaxel effectively inhibits canine ureteral smooth muscle cell proliferation and collagen production without toxicity to smooth muscle cells at concentrations up to 100 nM. These results may ultimately translate into new methods of preventing and treating urinary stricture disease.

Axial Diameter is Superior to Volumetric Measurement in Predicting Ureteral Stone Passage.

INTRODUCTION: We sought to investigate the clinical utility of volumetric measurements in predicting passage of symptomatic ureteral calculi. METHODS: We performed a retrospective review of patients seen in the emergency department for computerized tomography-confirmed symptomatic ureteral calculi with a subsequent discharge for trial of passage. Patient demographics and results of the passage trial were recorded. Stone parameters including location, 2-dimensional linear measurements and 3-dimensional volume measurements were calculated. Univariate and multivariate analyses were performed to evaluate the association between the aforementioned stone parameters and stone passage. RESULTS: A total of 70 patients were analyzed, of whom 37 (53%) passed their stones. On univariate analysis, patients who passed their stones had shorter axial diameters (mean±SD 3.3±1.3 mm vs 5.1±1.7 mm, p <0.01) and smaller volumes (0.03±0.02 cm3 vs 0.10±0.08 cm3, p <0.01). Stones that passed had traversed 79% of the ureter on presentation, compared to 41% for the stones that did not pass (p <0.01). Multivariate analysis demonstrated that shorter axial diameter was independently associated with stone passage (OR 0.46 [CI 0.29-0.71], p <0.01). Inclusion of stone volume measurements into the logistic regression model, however, provided no additional benefit for predicting stone passage rates (p=0.28). CONCLUSIONS: Although a stone's volume is expectedly correlated with passage, it does not seem to provide additional benefit when the stone's axial diameter and location within the ureter are known. Based on our findings, additional investment of time and resources into 3-dimensional modalities may not be warranted in this setting.

Proton-pump inhibitors associated with decreased urinary citrate excretion.

INTRODUCTION: Proton-pump inhibitors (PPIs) may increase the risk of kidney stone formation, but the mechanism has not been elucidated. There is a paucity of literature evaluating the effects of PPIs on urinary metabolites and urine pH. METHODS: We performed a retrospective review of nephrolithiasis patients treated at our institution and compared patients who were taking PPIs to those who were not at the time of their 24-h urine collections. Hierarchical multivariate linear regression was used to evaluate the independent relationship between PPI use and urinary mineral composition. RESULTS: We identified 301 consecutive patients, 88 (29%) of whom were taking PPIs at the time of their 24-h urine collections. Patients taking PPIs were older and more likely to have medical comorbidities associated with metabolic syndrome such as hypertension, diabetes, and dyslipidemia (p < 0.01). Controlling for these factors, patients taking PPIs were found to have 12% lower 24-h urine citrate excretion (ß = - 0.12, ΔF = 4.24, p = 0.04). There were no other differences in urinary mineral composition between the groups. CONCLUSION: Our findings suggest that patients who take PPIs regularly may be at risk for decreased urinary citrate excretion. The consequent decrease in urinary citrate may become clinically significant for patients with other predisposing factors for hypocitraturia.