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Objective: To compare the manufacturing and in vitro performance characteristics of two single-use flexible ureteroscopes with a permanent optical flexible ureteroscope. Materials and Methods: Two single-use flexible ureteroscopes, LithoVue (Boston Scientific) and Pusen (1rs. generation; Zhuhai Pusen Medical Technology Company Limited, China), were tested and compared with a permanent Flex-X² ureteroscope (Karl Storz, Germany) in terms of technical characteristics, optics, deflection mechanism, and additional parameters which could potentially affect surgical technique. Results: Pusen was the lightest ureteroscope while the LithoVue had the longest working length. LithoVue had a higher resolution power than the other two ureteroscopes at all distances tested (p < 0.001). Pusen showed higher resolution than Flex-X² (p < 0.01). Field of view was wider for LithoVue (87°), followed by Flex-X² (85°) and Pusen (75°). Color representation was superior for Flex-X² than LithoVue and then Pusen. LithoVue outperformed Pusen and Flex-X² for all settings with instruments in terms of deflection loss (p < 0.01). Pusen had the highest irrigation flow (52 mL/min) with an empty working channel (p < 0.01). LithoVue and Pusen showed similar flow rates with a 200 lm (21 mL/min) and 365 lm laser fiber (7 mL/min) and 1.3F basket (18 mL/min), being superior to Flex-X² (p < 0.01). With the 1.9F basket, LithoVue had superior flow rate (7 mL/min) than Pusen (3.5 mL/min) and Flex-X² (4 mL/min; p = 0.01). Conclusion: LithoVue outperformed the other ureteroscopes in terms of optical resolution, field of view, deflection capacity, and irrigation flow with larger instruments. Pusen is the lighter scope and showed better results in terms of irrigation when no instruments are in place. Flex-X² was superior in terms of color representation. [ABSTRACT FROM AUTHOR]

Purpose: To assess trends in urologic surgical management of upper tract urolithiasis in Brazil over the past 15 years. Materials and Methods: The Public Health System of Brazil (SUS) provides health coverage to 47% to 74% of the population. SUS has a longitudinal hospital inpatient database (SIH/SUS). Hospital discharges between January 1,1998 and December 31, 2012 were abstracted from the SIH/SUS. All inpatient hospitalizations for patients of any age with a primary/secondary diagnosis code of N20.x (calculus of kidney or ureter) were abstracted (ICD-9/10). All urolithiasis-related procedure codes were analyzed. The absolute number of procedures/year and the proportion among all techniques were analyzed for Brazil and also separately for the five distinguished regions of the country. Prevalence trends over the studied period were quantified by the estimated annual percent change (EAPC) using the least squares linear regression methodology. Significance was set at P<0.05. Results: The number of surgical interventions for stone disease increased significantly from 10080 to 24713 (+145%; EAPC=1008.1; P<0.001). The most common surgical modalities in 1998 were nephrectomy (n=2918; 29%), ureterolithotomy (n=2361; 23%), and pyelolithotomy (n=1771; 18%). In 2012, ureteroscopy (URS) was the most commonly performed procedure (n=8725; 35%), followed by ureterolithotomy (n=5822; 24%), and nephrectomy (n=3466; 14%). Between 1998 and 2012, percutaneous nephrolithotomy had the highest significant relative increase (+791.8%; EAPC=0.6%; P<0.001), followed by URS (+607%; EAPC=1.78%; P<0.001). Pyelolithotomy showed the most significant decrease (−47.5%; EAPC = −0.91%; P<0.001). All five regions presented a significant positive increase in the EAPC ( P<0.001). Conclusion: Trends of stone disease surgical management in the public health system of Brazil follow worldwide tendencies toward less invasive treatment modalities. [ABSTRACT FROM AUTHOR]

Objective: To study several measurements from a single-energy noncontrast computed tomography (NCCT) that may distinguish calcium oxalate, uric acid, and cystine stones. Methods: Patients with pure urinary stones who had at least 1 single-energy NCCT before the stone composition analysis from January 2008 to December 2012 were enrolled in this study. The analyzed data comprised stone size, volume, core Hounsfield unit (HU), periphery HU, absolute and relative HU differences between core and periphery, and HU density. After these measurements, an NCCT bone window was subjectively evaluated to study the homogeneity of each stone from core to periphery. The Spearman correlation test was used to determine the correlation between HU values and stone size and volume for each group. Results: A total of 113 patients were found with pure urinary stones who also had a corresponding NCCT. There were 36, 47, and 30 patients in the calcium oxalate, uric acid, and cystine groups, respectively. The core HU, periphery HU, absolute and relative HU differences, and HU density were significantly different among the 3 groups (P <.001). Stone size and volume had a positive correlation with core and periphery HUs only for calcium oxalate and cystine stones. The subjective evaluation of the urinary calculi revealed a different pattern for each stone composition. Conclusion: Single-energy NCCT may predict calcium oxalate stones with a high degree of accuracy. There is an overlap in radiographic profiles of cystine and uric acid stones, making a definitive differentiation more challenging. [Copyright &y& Elsevier]

Objective: To evaluate the ability of the Guy's stone score (GS) to predict the success rates and complications on the basis of the computed tomographic (CT) scan findings for renal stones treated with percutaneous nephrolithotomy (PCNL). Methods: From 2008 to 2012, a total of 147 consecutive patients (155 renal units) who underwent PCNL in a completely supine position were prospectively evaluated. All patients underwent a CT scan preoperatively, and the stones were classified according to the GS. All PCNLs were analyzed to determine the association between the GS and treatment outcomes on the basis of CT findings and complications, according to the Clavien criteria. Results: Of the 155 PCNLs, 27% were classified as GS1, 28.4% as GS2, 27% as GS3, and 17.6% as GS4. Only the largest diameter of the stones differed among the groups (GS1 = 21.4, GS2 = 26.5, GS3 = 31.4, and GS4 = 50.5 mm; P <.001). After stratification according to the GS, the groups differed significantly regarding their operative times (GS1 = 63 ± 28.5, GS2 = 101.4 ± 40.8, GS3 = 127.6 ± 47.6, and GS4 = 153.3 ± 56 minutes; P <.001), tubeless rates (GS1 = 54.8%, GS2 = 45.4%, GS3 = 28.6%, and GS4 = 7.4%; P <.001), blood transfusion rates (GS1 = 0%, GS2 = 2.3%, GS3 = 4.8%, and GS4 = 22.2%; P = .01), complications (GS1 = 4.8%, GS2 = 9.1%, GS3 = 26.2%, and GS4 = 44.4%; P <.001), immediate success rates (GS1 = 95.2%, GS2 = 79.5%, GS3 = 59.5%, and GS4 = 40.7%; P <.001), and number of auxiliary procedures (GS1 = 0.05 ± 0.32, GS2 = 0.28 ± 0.6, GS3 = 0.35 ± 0.66, and GS4 = 0.43 ± 0.59; P = .031). The final success rates after the auxiliary procedures were similar among the groups (GS1 = 97.6%, GS2 = 86.4%, GS3 = 90.5%, and GS4 = 74.5%; P = .19). Conclusion: The GS based on CT findings accurately predicted success rates and complications after PCNL for renal stones. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the functional characteristics of different ureteroscopic graspers. Methods: The Captura (2.8F, Cook Medical, Bloomington, IN), Platinum (3.0F, Bard Urological, Covington, GA), TriClaw (2.4F, UroGyn Medical, Inc., Valapraiso, IN), Graspit (2.6F, Boston Scientific, Natick, MA), and Boston Scientific Tricep (2.4F, 3.0F, and 3.0F non-retracting) graspers were tested. Opening dynamics were evaluated using high-resolution images. Grip strength was determined by measuring the maximum tensional force applied while grasping stone models attached to an inline load cell. Safety profile was evaluated by the maximum force required to perforate aluminum foil. Impact on ureteroscope deflection was assessed by measurement of maximum deflection (baseline = 247°) and bending radius after advancing each grasper through a flexible ureteroscope working channel. The Tukey test for inequality assuming unequal variance with Bonferroni adjustment was used to compare grip strength and perforation forces. Results: The Tricep (2.4F, 3.0F NR, and 3.0F) and Captura graspers required the least distance (7.9-8.1 mm) to attain a grasping width of 5 mm. When compared across all stone models, the TriClaw and Graspit had greater grip strengths than all other devices. The Captura (1.92 ± 0.43 N) and Tricep 2.4F (1.72 ± 0.88 N) required the greatest forces to perforate aluminum foil. Ureteroscope deflection was least impacted by the Tricep 2.4F (213°, 1.35 cm radius), Graspit (207°, 1.35 cm radius), TriClaw (206°, 1.3 cm radius), and all graspers could be deployed and operated at maximum deflection. Conclusion: There are significant differences in opening dynamics, grip strength, perforation forces, and ureteroscope deflection among ureteroscopic graspers that may predict clinical performance capabilities. [ABSTRACT FROM AUTHOR]

Objective: To elucidate the effect of a patient-centered combined nutritional and medical therapy approach on stone disease management, guided by 24-hour urinary stone risk. Materials and Methods: We retrospectively analyzed the records of patients treated at our multidisciplinary stone clinic from July 2007 to February 2009. Included were adult stone formers who presented with severe urinary abnormalities or whose urinary parameters failed to improve with dietary changes. Urinary risk factors for stone disease were evaluated before and after intervention with 24-hour urine collections. Hypercalciuria was treated with hydrochlorothiazide/indapamide, hypocitraturia with potassium/calcium citrate, and hyperuricosuria with allopurinol. The primary end point was the effect of combined dietary and medical intervention on levels of urinary metabolites. Statistical comparisons of postintervention urine collection values with baseline values were performed using a paired t test. Two-tailed P <.05 was considered statistically significant. Results: Data for 137 patients with a mean follow-up of 14.39 months were analyzed. Mean age was 47.2 years, and the male-to-female ratio was 1.04. Hypocitraturia was detected in 70 patients (51%), hypercalciuria in 49 (37%) and hyperuricosuria in 18 (13%). A significant improvement was found in 67% of patients with hypocitraturia (urinary citrate levels: 380.28 to 663.96 mg/d; P <.0001), in 82% of patients with hypercalciuria (urinary calcium levels: 337.4 to 183.6 mg/d; P <.0001), and in 72% of patients with hyperuricosuria (urinary citric acid level: 927 to 600 mg/d; P <.0001). Conclusion: Medical management of stone disease instituted based on individual risk factors impacts subsequent urinary stone risk, supporting its use for stone disease when patients do not respond to lifestyle and dietary changes. [ABSTRACT FROM AUTHOR]

Background: The purpose of our study was to determine, in vivo, whether single-energy noncontrast computed tomography (NCCT) can accurately predict the presence/percentage of struvite stone composition. Methods: We retrospectively searched for all patients with struvite components on stone composition analysis between January 2008 and March 2012. Inclusion criteria were NCCT prior to stone analysis and stone size ≥4 mm. A single urologist, blinded to stone composition, reviewed all NCCT to acquire stone location, dimensions, and Hounsfield unit (HU). HU density (HUD) was calculated by dividing mean HU by the stone's largest transverse diameter. Stone analysis was performed via Fourier transform infrared spectrometry. Independent sample Student's t-test and analysis of variance (ANOVA) were used to compare HU/HUD among groups. Spearman's correlation test was used to determine the correlation between HU and stone size and also HU/HUD to % of each component within the stone. Significance was considered if p<0.05. Results: Fourty-four patients met the inclusion criteria. Struvite was the most prevalent component with mean percentage of 50.1%±17.7%. Mean HU and HUD were 820.2±357.9 and 67.5±54.9, respectively. Struvite component analysis revealed a nonsignificant positive correlation with HU ( R=0.017; p=0.912) and negative with HUD ( R=−0.20; p=0.898). Overall, 3 (6.8%) had <20% of struvite component; 11 (25%), 25 (56.8%), and 5 (11.4%) had 21% to 40%, 41% to 60%, and 61% to 80% of struvite, respectively. ANOVA revealed no difference among groups regarding HU ( p=0.68) and HUD ( p=0.37), with important overlaps. When comparing pure struvite stones ( n=5) with other miscellaneous stones ( n=39), no difference was found for HU ( p=0.09) but HUD was significantly lower for pure stones (27.9±23.6 v 72.5±55.9, respectively; p=0.006). Again, significant overlaps were seen. Conclusions: Pure struvite stones have significantly lower HUD than mixed struvite stones, but overlap exists. A low HUD may increase the suspicion for a pure struvite calculus. [ABSTRACT FROM AUTHOR]

We report a case of a 75-year-old male with biopsy-proven prostate cancer and candidate for radical prostatectomy. The patient's medical history includes hypertension and atrial fibrillation in prophylactic treatment; however, he was suffering from recurrent paroxysmal episodes of supraventricular tachycardia. Abdominal magnetic resonance performed for prostate cancer staging detected a non-lymphatic inter-cavo-aortic mass of 42 × 37 × 43 cm. Results of biochemical screening confirmed the clinical diagnosis of symptomatic paraganglioma. The patient was subjected in a single robotic session for concurrent excision of the inter-aortocaval mass and radical prostatectomy with bilateral pelvic lymphnode dissection. During the procedure, there were no anesthesiological or surgical complications. The postoperative course was uneventful and the patient was discharged on postoperative day 5. Six months after surgery, his prostate-specific antigen level was undetectable and the abdominal magnetic resonance imaging was negative for local recurrence or metastasis of paraganglioma. No more episodes of tachycardia were reported or antihypertensive therapy was necessary. [ABSTRACT FROM AUTHOR]

Purpose: We searched for perioperative renal function deterioration risk factors in patients that underwent bilateral flexible ureteroscopy (fURS) for kidney stones. Methods: From August 2016 to February 2020, symptomatic patients > 18 years old with bilateral kidney stones up to 20 mm in each side were prospectively studied. Serum creatinine samples were collected on admission to surgery, immediate postoperative (IPO), on POD 3, 10, and 30. Estimated glomerular filtration rate (eGFR) was calculated using Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) without a race coefficient. Results: Thirty patients underwent bilateral fURS. Comparing to preoperative eGFR, median IPO and POD3 eGFR (p < 0.001) were significantly lower, and POD10 (p = 0.092) and POD30 (p = 0.648) were similar to preoperative eGFR. During follow-up, 22/30 (73.3%), 14/30 (46.7%), and 7/30 (23.3%) of the patients presented a decrease > 10% eGFR, > 20% eGFR, and > 30% eGFR, respectively. Multivariate analysis demonstrated that lower preoperative eGFR is a risk factor for eGFR < 60 mL/min/1.73 m2, p = 0.019 [1.021–1.263; 1.136]; ASA > 1 is a risk factor for decrease of eGFR > 10%, p = 0.028 [1.25–51.13; 8.00]; longer operative time is a risk factor for decrease of eGFR > 20%, p = 0.042 [1.00–1.05; 1.028]; and operative time ≥ 120 min is a risk factor for decrease of eGFR > 30%, p = 0.026 [0.016–0.773; 0.113]. Conclusions: Renal function suffers a reversible decrease after bilateral fURS. Our study suggests that adequate selection of patients and maintaining operative time < 120 min are relevant factors in preventing acute renal function deterioration following bilateral fURS. [ABSTRACT FROM AUTHOR]

Background: Despite technology incorporation to percutaneous nephrolithotomy (PCNL), residual stone fragments (RSFs) may still persist after PCNL and need to be addressed to avoid regrowth or ureteral obstruction. The objective of this study was to compare the outcomes of retrograde intrarenal surgery (RIRS) to extracorporeal shockwave lithotripsy (SWL) for treating patients with RSFs after a previous standard PCNL. Materials and Methods: Adult patients with RSF after a standard PCNL submitted to RIRS or SWL in our Institution from January 2017 to January 2020 were retrospectively studied. Stone-free rate (SFR) was evaluated on postoperative day (POD) 90 by noncontrast CT (NCCT) or ultrasound and kidney, ureter, and bladder radiograph (KUB) for each renal unit. Surgical complications based on Clavien–Dindo classification during the 90 days of follow-up were recorded. Sample size was calculated for a power of 80% and a significance level of 0.05, assuming SFR of 20% for SWL and 50% for RIRS. Results: Thirty-three patients treated by SWL were compared with 36 patients treated by RIRS. Hospitalization time was longer in the RIRS group (4.18 vs 12.33 hours, p = 0.001). SFR and success rate were lower in SWL than RIRS group (24.2% vs 58.3%, p = 0.007 and 30.3% vs 72.2%, p = 0.004, respectively), using POD 90 NCCT in 81.8% and ultrasound and KUB in 18.2% of the SWL group and using POD 90 NCCT in 100% of the RIRS group. Minor complications (Clavien–Dindo < III) occurred in 11 of 36 (30.6%) patients submitted to RIRS and in 2 of 33 (6.1%) patients submitted to SWL group (p = 0.025). Two patients (6.1%) of the SWL group had Clavien–Dindo IIIb complication owing to Steinstrasse and were submitted to ureteroscopy. Emergency room visits were similar between groups (6.1% vs 8.3%, p = 1.0). Conclusions: RIRS has better SFR, higher minor complications, and lower major complications than SWL for the treatment of RSFs after standard PCNL. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to prospectively compare the outcomes of bilateral same-session retrograde intrarenal surgery (BSS RIRS) with unilateral RIRS and to compare the outcomes of first with second operated kidneys in BSS RIRS. Subjects and Methods: Consecutive symptomatic adult patients with kidney stones up to 20 mm who accepted to be treated by RIRS were prospectively studied. Stone-free rate (SFR) was evaluated by non-contrast CT for each renal unit, and surgical complications were evaluated based on Clavien-Dindo classification. Results: SFR (73.9% vs 76.1%, p = 0.830) and hospitalization time (14.43 ± 18.81 hours vs 13.00 ± 4.89 hours, p = 0.564) were similar between unilateral and BSS RIRS groups, with less consumption of disposable devices in BSS RIRS (p = 0.017). Operative time was longer in BSS RIRS (61.24 ± 26.62 minutes vs 88.65 ± 33.19 minutes, p < 0.001). Bilateral group had significant more overall complications by Clavien-Dindo classification than unilateral (15.9% vs 39.9%, p = 0.030) and more emergency room (ER) visits (11.6% vs 34.8%, p = 0.026). Moreover, although both groups temporarily increased creatinine levels, it was significantly higher in bilateral RIRS (p = 0.019). First operated kidney outcomes were similar to second operated kidney outcomes of BSS RIRS. Conclusion: Although BSS RIRS had similar SFR and consumed less disposable devices, it had a higher overall complication rate, a higher frequency of ER visits, and higher creatinine levels during follow-up than unilateral RIRS. There is no significant outcome difference between first and second operated kidneys in BSS RIRS. [ABSTRACT FROM AUTHOR]

Purpose: We searched for perioperative renal function deterioration risk factors in patients that underwent bilateral flexible ureteroscopy (fURS) for kidney stones. Methods: From August 2016 to February 2020, symptomatic patients > 18 years old with bilateral kidney stones up to 20 mm in each side were prospectively studied. Serum creatinine samples were collected on admission to surgery, immediate postoperative (IPO), on POD 3, 10, and 30. Estimated glomerular filtration rate (eGFR) was calculated using Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) without a race coefficient. Results: Thirty patients underwent bilateral fURS. Comparing to preoperative eGFR, median IPO and POD3 eGFR (p < 0.001) were significantly lower, and POD10 (p = 0.092) and POD30 (p = 0.648) were similar to preoperative eGFR. During follow-up, 22/30 (73.3%), 14/30 (46.7%), and 7/30 (23.3%) of the patients presented a decrease > 10% eGFR, > 20% eGFR, and > 30% eGFR, respectively. Multivariate analysis demonstrated that lower preoperative eGFR is a risk factor for eGFR < 60 mL/min/1.73 m2, p = 0.019 [1.021–1.263; 1.136]; ASA > 1 is a risk factor for decrease of eGFR > 10%, p = 0.028 [1.25–51.13; 8.00]; longer operative time is a risk factor for decrease of eGFR > 20%, p = 0.042 [1.00–1.05; 1.028]; and operative time ≥ 120 min is a risk factor for decrease of eGFR > 30%, p = 0.026 [0.016–0.773; 0.113]. Conclusions: Renal function suffers a reversible decrease after bilateral fURS. Our study suggests that adequate selection of patients and maintaining operative time < 120 min are relevant factors in preventing acute renal function deterioration following bilateral fURS. [ABSTRACT FROM AUTHOR]

Double-J displacement is a negative point for any RIRS and we agree that stent string should be avoided in BSS-RIRS because of its consequences, although we could not find this conclusion on previous reports. Moreover, the complication rate of BSS-RIRS reported in our study would continue to be higher than unilateral RIRS even if divided by half. B Dear Editor, b Bilateral same session retrograde intrarenal surgery (BSS-RIRS) is an appealing procedure; however, a few studies were published regarding its outcomes. [Extracted from the article]

Background: Percutaneous nephrolithotomy (PCNL) can be performed in the prone or in the supine position. Comparisons between the two techniques in obese patients are rare in the current literature. Methods: The records of obese patients (body mass index >30) who underwent PCNL in the prone or complete supine positions were reviewed. All patients had a noncontrast CT before and after the procedure. Stones were graded according to the Guy stone score and complications according to the Clavien grading. The stone-free rates, operative time, surgical complications, and hospital stay were analyzed. Results: A total of 56 PCNL were performed in 42 patients. Twenty-four PCNL were performed in the prone and 32 in the total supine position. Stone-free rate on the first postoperative day was 50% in the prone and 46.9% in the supine position ( P=1.0). Final stone-free rates were 83.3% and 78.1%, respectively ( P=0.74). Mean operative time was 164.6 minutes in the prone and 120.3 minutes in the supine position ( P=0.0017), and hospital stay was 4.38 and 2.68 days ( P=0.014), respectively. The transfusion rate was 20.8% in the prone and zero in the supine position patients ( P=0.01). Excluding Guy IV stones, transfusion rate was 8.3% in the prone position ( P=0.1). Significant surgical complications rate was 12.5% in the prone and 3.1% in the supine position ( P=0.302). Conclusion: PCNL performed in the prone or in the complete supine position in obese patients presents similar outcomes. The supine decubitus position has the advantages of a significantly shorter operative time and hospital stay. [ABSTRACT FROM AUTHOR]

Objective: To define computed tomography (CT) predictors of residual fragments after retrograde intrarenal surgery (RIRS) for kidney stones up to 20 mm in patients never submitted to surgical procedures for stone removal.Methods: From August 2016 to August 2017, symptomatic adult patients with kidney stones less than 20 mm treated by RIRS had their pre- and postoperative CT prospectively evaluated in search for predictors of residual stone fragments. Stone size, stone volume, number of stones, stone density, and location were evaluated in preoperative CT and analyzed as predictors for residual stone fragments on 90 POD CT. Stone location was represented by the infundibulopelvic angle (IPA) measured for each stone on preoperative noncontrast CT using multiplanar reconstruction.Results: Ninety-two patients were successfully submitted to RIRS. Bilateral procedures were performed in 23 patients (25%) resulting in 115 renal units operated. Operative time was 54.5 ± 26.7 minutes (mean ± SD) and 96.7% (89/92) of the patients were discharged up to 12 hours after the procedure. Postoperative CT demonstrated stone-free in 86 of 115 (74.8%), 0-2 mm in 10 of 115 (8.7%), and > 2 mm residual fragments in 19 of 115 (16.5%) procedures. Logistic regression analysis revealed steep IPA was a predictor for any residual stone fragment after RIRS for kidney stones < 20 mm (P= .012). ROC curve showed that IPA < 41° was associated with a higher chance of residual fragments after RIRS.Conclusion: IPA < 41° is associated with a higher chance of residual fragments after RIRS for kidney stones up to 20 mm. [ABSTRACT FROM AUTHOR]

Objectives: To define the most suitable approach to assess residual stone fragments after retrograde intrarenal surgery (RIRS). Methods: Ninety-two patients (115 renal units) submitted to RIRS for symptomatic kidney stones >5 mm and <20 mm or <15 mm in the lower Calyx diagnosed by noncontrast CT (NCCT) were prospectively studied. Residual fragments were assessed by endoscopic evaluation (END) at the end of the procedure and by NCCT, ultrasonography (US), and kidney, ureter, and bladder radiograph (KUB) on the 90th postoperative day (POD). NCCT was considered the gold standard for the evaluation of residual fragments after RIRS. Results: The 90th POD NCCT resulted in stone-free status in 74.8% (86/115), 0–2 mm in 8.7% (10/115), and >2 mm residual fragments in 16.5% (19/115) renal units. Stone-free status by END at the end of RIRS was coincident with NCCT in 93.0% of the cases (40/43). There were no cases of residual fragments >2 mm on NCCT if END resulted in stone-free status. In all cases where END resulted in residual fragments >2 mm, US proved to be correct according to NCCT. Neither US nor KUB was able to identify residual fragments between 0 and 2 mm. KUB had only 31.6% (6/19) sensitivity to detect residual fragments >2 mm and did not add sensitivity or specificity to US. Conclusions: In the follow-up imaging after RIRS, we suggest that if END resulted in residual fragments <2 mm, a 90th POD NCCT should be performed. US may be used if END showed fragments >2 mm. [ABSTRACT FROM AUTHOR]