Variables measured on three-dimensional computed tomography are preferred for predicting the outcomes of shock wave lithotripsy.

PURPOSE: Shock wave lithotripsy (SWL) is used to treat upper urinary tract stones. Recently, some volume analyzers have enabled preoperative assessment using three-dimensional computed tomography (3D-CT). We evaluated the efficacy of 3D-CT variables for predicting the outcomes of SWL. METHODS: The study population included 193 patients who underwent SWL between November 2014 and August 2020. In addition to conventional two-dimensional computed tomography (2D-CT) assessments, 3D-CT assessments of targeted stones were retrospectively performed, and stone size and stone density (SD) were measured. The successful and unsuccessful treatment groups were compared and risk factors for an unsuccessful first SWL session were investigated. The predictive accuracy of variables measured on 3D-CT was evaluated by receiver operating characteristic curves and multivariate analyses. RESULTS: The success rate of the first SWL session was 73.1%. Stone volume, mean SD and highest SD on 3D-CT were significantly higher in the unsuccessful group than in the successful group. Stone volume showed a higher area under the curve (AUC) than the estimated volumetric stone burden and stone diameter, which were measured on 2D-CT (0.729, 0.683, and 0.672, respectively). The AUCs of the mean SD and highest SD on 3D-CT were higher than those on 2D-CT (0.699, 0.680, 0.617, and 0.627, respectively). Multivariate analyses identified stone volume (≥ 0.29 ml), mean SD on 3D-CT (≥ 421 HU), and absence of hydronephrosis as independent predictive factors for unsuccessful SWL. CONCLUSION: 3D-CT variables were promising predictors of the outcomes of SWL. Preoperative 3D-CT assessment is helpful for selecting favorable patients for SWL.

Risk factors and predictive model for incidence of difficult ureter during retrograde ureteroscopic lithotripsy.

OBJECTIVE: Difficult ureter can be a challenge for accessing upper urinary tract during lithotripsy. In this study, we evaluated the risk factors for the incidence of difficult ureter in retrograde ureteroscopic lithotripsy. Moreover, we aimed to develop a predictive model for the incidence of difficult ureter. METHODS: We retrospectively reviewed consecutive retrograde ureteroscopic lithotripsies performed at our institution between 2009 and 2021. A total of 1010 renal units were evaluated: 449 units with renal stones only and 561 units with ureteral stones, with or without renal stones. RESULTS: The overall incidence of difficult ureter was 5.9%, with a higher incidence in the renal alone stone group than in the ureteral stone group (7.8% vs 4.5%, P = 0.026). Multivariate regression analysis revealed three risk factors for the incidence of difficult ureter: absence of stone history (odds ratio 5.67, 95% confidence interval 2.40-13.4, and P < 0.001), age ≤45 years (odds ratio 3.61, 95% confidence interval 2.05-6.37, and P < 0.001), and renal stone only (odds ratio 2.11, 95% confidence interval 1.22-3.64, and P = 0.008). A simple model using these three risks enabled the stratification of the incidence rate of difficult ureter, with the incidence of high-risk cases being 12.7%. CONCLUSIONS: The greatest risk factor for the incidence of difficult ureter was the absence of stone history, followed by age 45 years or younger, and having only renal stones. In high-risk cases of difficult ureter, the possibility of secondary lithotripsy should be explained to the patients.

Stone-event-free survival after ureteroscopic lithotripsy by age: comparison between young and older patients.

The aim of this study is to examine stone-event-free survival after ureteroscopic lithotripsy (URSL) and risk factors for stone events by age. We retrospectively collected data of all URSL cases at our institution from 2008 to 2021. A total of 1334 cases were included and divided into young (< 65 years, 792 cases), young-old (65-74 years, 316 cases), old-old (75-84 years, 172 cases), and oldest-old (≥ 85 years, 54 cases) groups. Patient characteristics, surgical outcomes, and postoperative stone events were evaluated. The stone-event-free survival and risk factors were compared between young and older groups. Overall, 214 (16.0%) cases developed stone events during a mean follow-up period of 763 days and the 2-year, 5-year, and 8-year stone-event-free survival rates were 84.5%, 72.2%, and 57.2%, respectively. The numbers of stone events in young, young-old, old-old, oldest-old groups were 133 (16.8%), 53 (16.8%), 21 (12.2%), and 7 (13.0%), respectively. No significant differences were found in stone-event-free survival between the young group and each of the older groups. Residual fragment > 4 mm and stone burden ≥ 15 mm were common risk factors in both young and older groups. Especially in older patients, preoperative stenting, which was most often performed to treat obstructive pyelonephritis, was the third risk factor. In conclusion, stone-event-free survival after URSL was comparable between young and older patients. Residual fragment > 4 mm and stone burden ≥ 15 mm were common risk factors in both groups. Preoperative stenting was an additional risk factor in older patients, suggesting that urinary tract infection may influence stone events.

Different failure rates of insertion of 10/12-Fr ureteral access sheaths during retrograde intrarenal surgery in patients with and without stones.

PURPOSE: The aim of this study was to compare the failure rates of insertion of a 10/12-Fr ureteral access sheath (UAS) during retrograde intrarenal surgery (RIRS) in cases with and without stones and to analyze the risk factors for UAS insertion failure. MATERIALS AND METHODS: A total of 640 RIRS cases (538 with and 102 without stones) were evaluated. The primary outcome of interest was the failure rate of insertion of a 10/12-Fr UAS. Associated risk factors were assessed using univariate and multivariate logistic regression analyses. Propensity score (PS) matching and inverse probability of treatment weighting (IPTW) were used to ensure the robustness of the results. RESULTS: The overall failure rate of 10/12-Fr UAS insertion in the cases without stones was significantly higher than that in the cases with stones (39.2% vs. 7.2%; p<0.001), and was approximately 2.5 to 4 times higher after PS matching and IPTW. Multivariate logistic analyses showed that being in the group without stones and younger age were independent significant risk factors for insertion failure in both the PS-matched cohort (odds ratio [OR], 5.43; 95% confidence interval [CI], 2.16-13.6; and OR, 1.04; 95% CI, 1.01-1.07) and the IPTW-adjusted cohort (OR, 1.82; 95% CI, 1.14-2.90; and OR, 1.03; 95% CI, 1.01-1.04). CONCLUSIONS: The incidence of 10/12-Fr UAS insertion failure during RIRS was higher in cases without stones than in those with stones. These results provide valuable information for surgeons to use during informed consent discussions with patients undergoing RIRS, especially patients without stones.

Renal Angiomyolipoma Mimicking a Well-Differentiated Retroperitoneal Liposarcoma.

A 37-year-old Burmese woman presented with an incidentally found retroperitoneal fat-containing tumor. The tumor was 9 cm in the longest diameter, surrounding the right kidney, and composed of homogenous adipose tissue with thickened septum-like structures and spotty nonadipose structures, which were enhanced on contrast-enhanced computed tomography and magnetic resonance imaging. The tumor did not show either a beak sign or synchronous angiomyolipoma-like lesion in the kidneys. The tumor had irregular septa, thin blood vessels, and spotty small soft-tissue nodules. The tumor did not contain any heterogeneously enhanced solid lesions suspicious for dedifferentiated liposarcomas. Based on these imaging findings, a clinical diagnosis of a well-differentiated liposarcoma was made. Under the consensus of a multidisciplinary cancer board, she was recommended to undergo core-needle biopsy to confirm the clinical diagnosis. However, she declined to undergo biopsy for financial reasons. She underwent kidney-sparing retroperitoneal tumor resection. Histopathologically, the tumor was an angiomyolipoma with positive immunostaining for HMB45 and Melan A. The present case suggests the importance of core-needle biopsy prior to surgical intervention for retroperitoneal fat-containing tumors.