Search

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., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To demonstrate a successful 1-session approach to a complete calcified ureteral stent, preserving the affected kidney without complications., Patient and Methods: A 33-year-old man presented at our service with an increased urinary frequency, afebrile urinary tract infection, and left lumbar pain. He underwent a ureterolithotripsy with ureteral stenting 3 years ago. After that intervention, he was lost to follow-up. A noncontrast computed tomography scan revealed a complete calcified ureteral stent (FECal V). After careful preoperative planning, the patient was submitted to a combined 1-step approach including left semirigid ureteroscopy, left percutaneous nephrolithotomy, and an open cystolithotomy in supine decubitus. This video demonstrates the surgical steps of the procedure for a FECal V (completely calcified) stent removal., Results: Operative time was 240 minutes. The calcified stent was completely removed. A 6 Fr ureteral catheter and a 16 Fr nephrostomy tube were left at the end of the procedure. No double-J stent was used to avoid the same kind of complication. The patient had no peri- or postoperative complications. A computed tomography scan was performed in the first postoperative day (POD) and revealed 2 small residual fragments (7 mm and 6 mm). The ureteral catheter was removed on the first POD, and the nephrostomy tube on the second POD. The patient was discharged from hospital on the third POD. The patient is now scheduled to a flexible ureteroscopy to treat the small residual fragments., Conclusion: Forgotten ureteral stent is a surgical challenge, requiring multiple approaches and advanced urologic techniques. Our video illustrates that a less invasive and combined 1-step procedure to preserve the kidney is both safe and feasible, when performed by an experienced surgeon., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: To evaluate if renal function loss and hydronephrosis due to a silent ureteral stone might be reversed., Materials and Methods: We prospectively selected patients with silent ureteral stones between January 2006 and January 2014. A silent case was considered if there were no specific or subjective symptoms related to the ureteral stone. Patient, stone, and kidney characteristics were evaluated preoperatively, 3 and 12 months postoperatively. Renal function was accessed in the same intervals with serum creatinine (SCr), glomerular filtration rate (GFR), and (99m)Tc-dimercaptosuccinic acid. Patients without complete pre- and postoperative evaluation were excluded. Primary end point was midterm progress of global and ipsilateral renal function. Secondary end points included the evaluation of renal and collecting system anatomy from diagnosis to 12 months after treatment. Analysis of variance with repeated measures and marginal homogeneity test were used to evaluate renal function and hydronephrosis progression., Results: Twenty-six patients met our inclusion criteria. Mean preoperative SCr and GFR were 1.24 mg/dL and 72.5 mL/min, respectively. At initial scintigraphy, mean renal function was 33.4%. Laser ureterolithotripsy was performed in 84.6% of cases and all patients were rendered stone free. Two patients (8%) developed ureteral stenosis. There was no difference regarding SCr (P = .89), GFR (P = .48), and renal function at scintigraphy (P = .19) during follow-up. Hydronephrosis significantly improved from preoperatively to 3 months postoperatively (P < .0001), but not from 3 to 12 months (P = .065)., Conclusion: Patients with silent ureteral stones present with significant impairment of ipsilateral renal function and hydronephrosis at diagnosis. On midterm follow-up evaluation, renal function of the affected unit remains stable whereas hydronephrosis improves after treatment., (Copyright © 2016 Elsevier Inc. All rights reserved.)

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., (Copyright © 2014 Elsevier Inc. All rights reserved.)

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 © 2014 Elsevier Inc. All rights reserved.)

Objective: To evaluate the association of preoperative noncontrast computed tomography stone characteristics, laser settings, and stone composition with cumulative holmium:yttrium-aluminum-garnet (Ho:YAG) laser time/energy., Materials and Methods: We retrospectively reviewed patients who underwent semirigid/flexible ureteroscopy and Ho:YAG laser lithotripsy (200 or 365 μm laser fiber; 0.8-1.0 J energy; and 8-10 Hz rate) at 2 tertiary care centers (April 2010-May 2012). Studied parameters were as follows: patient's characteristics; stone characteristics (location, burden, hardness, and composition); total laser time and energy; and surgical outcomes., Results: One hundred patients met our inclusion criteria. Mean stone size was 1.01 ± 0.42 cm and volume 0.33 ± 0.04 cm(3). Mean stone radiodensity was 990 ± 296 HU, and Hounsfield units density 13.8 ± 6.0 HU/mm. All patients were considered stone free. Stone size and volume had a significant positive correlation with laser energy (R = 0.516, P <.001; R = 0.621, P <.001) and laser time (R = 0.477, P <.001; R = 0.567, P <.001). When controlling for stone size, only the correlation between HU and laser time was significant (R = 0.262, P = .011). In the multivariate analysis, with exception of stone composition (P = .103), all parameters significantly increased laser energy (R(2) = 0.524). Multivariate analysis revealed a positive significant association of laser time with stone volume (P <.001) and Hounsfield units density (P <.001; R(2) = 0.512). In multivariate analysis for laser energy, only calcium phosphate stones required less energy to fragment compared with uric acid stones. No significant differences were found in the multivariate laser time model., Conclusion: Ho:YAG laser cumulative energy and total time are significantly affected by stone dimensions, hardness location, fiber size, and power. Kidney location, laser fiber size, and laser power have more influence on the final laser energy than on the total laser time. Calcium phosphate stones require less laser energy to fragment., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Objective: To evaluate if different stone compositions can be distinguished by variations in Hounsfield unit (HU) patterns from stone core to periphery., Materials and Methods: We retrospectively reviewed our stone registry searching for pure uric acid (UA) and calcium oxalate (CaOx) stones. Inclusion criteria comprised: pure calculi; noncontrast computed tomography before stone analysis; and stone size ≥4 mm. A single urologist reviewed all images (abdominal/bone windows). Absolute HU attenuation was measured in the center (core) and edges (periphery) of each stone. HU density (HU/size) and stone volume were calculated. Categorical variables were compared with Chi-square/Fisher exact test; continuous with analysis of variance/Student t test. Spearman's test was used correlate HU values and stone dimensions. A P <.05 was considered significant., Results: Included were 47 UA and 36 CaOx stones. CaOx cohort had higher HU values for all parameters (P <.001). HU variation (core-periphery) was more homogeneous in the UA group (-25%) than in the CaOx group (-52%). Stone dimensions had a significant positive correlation with HU values in CaOx cohort. In the UA group, stone volume and periphery HU had significant positive correlation. On bone window, CaOx stones had a heterogeneous pattern with a higher attenuation core with decreasing attenuation toward the periphery; UA calculi had a more homogeneous constant frosted white cloudy appearance., Conclusion: Stone size does not affect HU for UA stone, but has a positive correlation with CaOx stone. UA stones can be differentiated from CaOx by evaluating variation in HU from core to periphery and by subjective evaluation of homogeneity in bone windows., (Copyright © 2013 Elsevier Inc. All rights reserved.)

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., (Copyright © 2013 Elsevier Inc. All rights reserved.)

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., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objective: To report our experience with silent ureteral stones and expose their true influence on renal function., Methods: We analyzed 506 patients who had undergone ureterolithotripsy from January 2005 to May 2010. Silent ureteral stones were calculi found in the absence of any specific or subjective ureteral stone-related symptoms. Of the 506 patients, 27 (5.3%) met these criteria (global cohort). All patients were assessed postoperatively with dimercaptosuccinic acid scintigraphy (DMSA). A difference in relative kidney function of >10% was considered abnormal. Pre- and postoperative comparative DMSA analyses were electively obtained for 9 patients (kidney function cohort). A t test was used to assess the numeric variables, and the chi-square test or Fisher's exact test was used for categorical variables. Two-tailed P<.05 was considered statistically significant., Results: Stones were diagnosed by radiologic abdominal evaluation for nonurologic diseases in 40% and after previous nephrolithiasis treatment in 33%. The primary therapy was ureterolithotripsy in 88%. The mean follow-up time was 23 months. The overall ureteral stone-free rate after 1 and 2 procedures was 96% and 100%, respectively. In the global cohort, the mean pre- and postoperative serum creatinine levels were similar (P=.39), and the mean postoperative function on DMSA was 31%. In the kidney function cohort, no difference was found between the pre- and postoperative DMSA findings (22%±12.1% vs 20%±11.8%; P=.83) and serum creatinine (0.8±0.13 mg/dL vs 1.0±0.21 mg/dL; P=.45)., Conclusion: Silent ureteral stones are associated with decreased kidney function present at the diagnosis. Hydronephrosis tends to diminish after stone removal, and kidney function remains unaltered., (Copyright © 2012 Elsevier Inc. All rights reserved.)