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.

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.

Association of Impaired Renal Function With Changes in Urinary Mineral Excretion and Stone Composition.

OBJECTIVE: To investigate the effect of kidney function on stone composition and urinary mineral excretion in patients undergoing surgical intervention for nephrolithiasis. METHODS: Using our institutional kidney stone database, we performed a retrospective review of stone patients who underwent surgical intervention between 2004 and 2015. Patients' demographic information, 24-hour urinary mineral excretion, and stone characteristics were reported. The patients' estimated glomerular filtration rates (eGFR) were compared with their stone compositions and 24-hour urine mineral excretions. RESULTS: A statistically significant difference was noted between the groups, with uric acid stones being associated with lower eGFR and calcium phosphate stones associated with higher eGFR. No relationship could be demonstrated between eGFR and calcium oxalate or struvite stones. Patients with lower eGFR also demonstrated a statistically significant association with lower urinary pH as well as lower urinary excretion of calcium and citrate. CONCLUSION: While various factors have been found to play significant roles in kidney stone formation and composition, our findings demonstrate a definite relationship between these and renal function. This paper highlights the fact that renal function evaluation should be considered an important component in the evaluation, counseling, and management of patients with nephrolithiasis.

Long-term Incidence of Hematuria, Urethral Stricture and Bladder Cancer after Radiation Therapy for Prostate Cancer.

INTRODUCTION: Approximately 25% of patients diagnosed with prostate cancer choose radiation therapy as the primary treatment for this malignancy. Urinary tract toxicity after radiation therapy impacts patients years after treatment of the malignancy. We describe the incidence of hematuria, urethral stricture and bladder cancer after radiation therapy, and measure the effect of the radiation therapy modality in patients with prostate cancer. METHODS: We performed a retrospective review of 886 consecutive patients who received radiation therapy for prostate cancer between 1992 and 2013. Prostate cancer clinical characteristics, radiation therapy treatment modality and events of interest (hematuria, urethral stricture disease and bladder cancer) were recorded. The Kaplan-Meier method was used to estimate the incidence of events of interest and multivariate stepwise Cox regression was performed to analyze associations. RESULTS: Radiation therapy modalities included external beam radiation therapy (379), brachytherapy (225), combination therapy (35) or post-prostatectomy radiation therapy (adjuvant 47 or salvage 201). Overall the 5 and 10-year risk (95% CI) of hematuria was 23% (19-27) and 42% (36-48), urethral stricture 7% (5-9) and 12% (8-16), and bladder cancer 2% (1-3) and 5% (3-7), respectively. On multivariate regression smoking was associated with hematuria (HR 2.5, p <0.001). Obesity (HR 2.5, p=0.005), combination therapy (HR 3.8, p=0.006) and adjuvant radiation therapy (HR 3.1, p=0.015) were associated with urethral stricture. CONCLUSIONS: Hematuria, urethral stricture and bladder cancer continue to develop several years after radiation therapy for prostate cancer, thereby warranting continued, long-term followup for these conditions.