SUMMARY OBJECTIVE: The aim of this study was to identify predictive factors for complications after percutaneous nephrolithotomy. METHODS: We prospectively analyzed patients who underwent percutaneous nephrolithotomy from June 2011 to October 2018. The association of preoperative and intraoperative factors with the presence of complications was assessed using univariate and multivariate analyses. The significance level was set at p<0.05. RESULTS: A total of 1,066 surgeries were evaluated, and the overall complication rate was 14.9%. In all, 105 (9.8%) surgeries were performed in the prone position, and 961 (90.2%) were performed in the supine position. Univariate analysis demonstrated that surgical position, upper pole puncture, surgical time, number of tracts, and Guys Stone Score were associated with complications. In multivariate analyses, prone position (odds ratio [OR] 2.10; p=0.003), surgical time ≥90 min (OR 1.76; p=0.014), upper pole puncture (OR 2.48; p<0.001), and Guys Stone Score 3 or 4 (OR 1.90; p=0.033) were independent predictive factors for complications after percutaneous nephrolithotomy. CONCLUSION: Performing percutaneous nephrolithotomy in the supine position, in under 90 min, and avoiding upper pole punctures may reduce complications during the treatment of large kidney stones.

SUMMARY OBJECTIVE: Mini-percutaneous nephrolithotomy is a recent advancement in the field of kidney stone treatment; however, its role has not been completely established. We aimed to compare the outcomes of initial Mini-percutaneous nephrolithotomy and flexible ureteroscopy. METHODS: A retrospective review of consecutive mini-percutaneous procedures was performed. Inclusion criteria were as follows: all percutaneous nephrolithotomy procedures performed with an access sheath up to 24Fr, kidney stone burdens up to 1550 mm3; and the presence of postoperative computed tomography (for control). The data collected for Mini-percutaneous nephrolithotomy procedures were paired 1:2 with patients treated with flexible ureteroscopy for stones between 100 and 1550 mm3, and with postoperative computed tomography for control. A 14Fr Mini-percutaneous nephrolithotomy set was used. The stone-free rate was defined as the absence of fragments on the control computed tomography, whereas success was limited to 2-mm residual fragments. Statistical analysis was performed using SPSS version 19. RESULTS: A total of 63 patients met the inclusion criteria (42 with flexible ureteroscopy and 21 with mini-percutaneous nephrolithotomy). Demographic data were comparable. The stone-free rate and success were similar between the groups (76.2 vs. 66.7%, p=0.42 and 90.5 vs. 85.7%, p=0.57). The complication rate was also similar (26.1 vs. 9.6%, p=0.188), but Mini-percutaneous nephrolithotomy had longer hospitalization and fluoroscopy time (p=0.001 in both). CONCLUSIONS: Our initial study of Mini-percutaneous nephrolithotomy showed that it is a promising procedure, with outcomes similar to flexible ureteroscopy, but with higher inpatient numbers and fluoroscopy times. A larger study population size and better equipment may improve the outcomes of mini-percutaneous nephrolithotomy.

ABSTRACT Flexible ureteroscopy is a well-established method for treatment of urinary stones but flexible ureteroscopes are expensive and fragile devices with a very limited lifetime. Since 2006 with the advent of digital flexible ureteroscopes a great evolution has occurred. The first single-use flexible ureteroscope was launched in 2011 and new models are coming to the market. The aim of this article is to review the characteristics of these devices, compare their results with the reusable devices and evaluate the cost-benefits of adopting single-use flexible ureteroscopes in developing countries. Materials and Methods: an extensive review of articles listed at PubMed and published between 2000 and 2021 was performed. Results: Single-use flexible ureteroscopes have a shaft with 65 to 68cm length and weight between 119 and 277g. Their deflection goes up to 300 degrees. Their stone-free rates vary between 60 and 95% which is comparable to reusable scopes and operative times ranges from 54 to 86 minutes which are lower when compared to reusable flexible scopes. Their costs vary between 800 and 3180 US dollars. Conclusion: single-use flexible ureteroscopes are lighter and have superior quality of image when compared to fiberoptic ones. There are no definite data showing a higher stone-free rate or less complications with the use of single-use flexible ureteroscopes. Each institution must perform a cost-benefit analysis before making the decision of adopting or not such devices depending on the local circumstances.

SUMMARY OBJECTIVE: The aim of this study was to evaluate the predictive factors for success following percutaneous nephrolithotomy in the supine position. METHODS: Patients who underwent percutaneous nephrolithotomy in the supine position from June 2011 to October 2018 were evaluated. Age, sex, body mass index, the American Society of Anesthesiologists physical status classification, hemoglobin level, number of previous surgeries, stone size, and the Guy’s Stone Score were analyzed. Success was considered if no fragments were observed on the computed tomography scan on the first postoperative day. Univariate and multivariate analyses were performed to determine significant parameters. RESULTS: We evaluated 961 patients; of them, 483 (50.2%) underwent previous stone-related surgery, and 499 (51.9%) had Guy’s Stone Score 3 or 4. The overall success rate in a single procedure was 40.7%, and complication rate was 13.7%. The univariate analysis showed that the maximum diameter of the stone (25.10±10 mm; p<0.001), previous percutaneous nephrolithotomy (OR 0.52; p<0.001), number of previous percutaneous nephrolithotomy (OR 0.15; p<0.001), the Guy’s Stone Score (OR 0.28; p<0.001), and the number of tracts (OR 0.32; p<0.001) were significant. In the multivariate analysis, the number of previous percutaneous nephrolithotomy (OR 0.54; p<0.001) and the Guy’s Stone Score (OR 0.25; p<0.001) were statically significant. CONCLUSIONS: Guy’s Stone Score and the number of previous percutaneous nephrolithotomy are predictors of success with the supine position. Complex cases and with previous percutaneous interventions may require technical improvements to achieve higher stone-free rates.

ABSTRACT Purpose: to evaluate the effect of low-calorie diet on 24-hour urinary metabolic parameters of obese adults with idiopathic calcium oxalate kidney stones. Materials and Methods: Adult idiopathic calcium oxalate stone formers, with body mass index (BMI) ≥30kg/m2 and a known lithogenic metabolic abnormality, were submitted to low-calorie diet for twelve weeks. After enrolment, anthropometric measures, serum exams, 24-hour urinary metabolic parameters and body impedance were collected one month prior to dietary intervention and at the end of twelve weeks. Correlations between weight loss, waist circumference loss, fat loss and variation in 24-hour urinary lithogenic parameters and calcium oxalate urinary supersaturation (CaOx SS) as per Tiselius equation were analysed. Results: From January 2017 to January 2018, 39 patients were enrolled to participate in this study. Median (range) prescribed diet was 1300 (1100-2100) Kcal/day. Mean age was 51.7±11.0 (29-68) years old and 69.2% were female. 30.8% of the participants shifted from obesity to BMI <30kg/m2 and none to BMI <25kg/m2. A significant correlation was found between baseline 24-hour urinary oxalate and weight (p=0.018) and BMI (p=0.026). No correlation was found between variation of weight, waist circumference, fat mass and 24-h urinary stone risk factors or CaOx SS. Conclusions: Short-term modest weight loss induced by twelve weeks of low-calorie diet is not associated with a decrease of 24-hour urinary lithogenic parameters in idiopathic calcium oxalate stone formers. Calcium oxalate urinary stone formation is probably multifactorial and driven by other factors than weight.

ABSTRACT Purpose: The objective of this study is to evaluate the impact of a previous standard percutaneous nephrolithotomy (PCNL) on the outcomes of retrograde intrarenal surgery (RIRS). Materials and Methods: Outcomes of RIRS performed from January 2017 to January 2020 in adult patients with residual stone fragments ≤20mm after a standard PCNL (Post-PCNL) and symptomatic adult patients with kidney stones ≤20mm (Control) were prospectively studied. Stone-free rate (SFR) was evaluated on a postoperative day 90 non-contrast computed tomography. Surgical complications based on Clavien-Dindo classification during the 90 days of follow-up were recorded. Results: Outcomes of 55 patients and 57 renal units of the post-PCNL group were compared to 92 patients and 115 renal units of the control group. SFR was lower in post-PCNL group than in control (28/57, 49.1% vs. 86/115, 74.8%, p <0.001). Overall complications were more frequent in post-PCNL group (p=0.004). Infundibula strictures were identified and incised with laser in 15/57 (26.3%) renal units of the post-PCNL group. Thirteen renal units had infundibulum stricture at the site of previous percutaneous tract (13/15; 86.7%, p=0.004) and one renal unit had three infundibula strictures. Postoperative complications were not affected by the treatment of infundibula strictures (p=0.198). Conclusions: Previous standard PCNL significantly impairs the outcomes of RIRS. Infundibula strictures can be found in 26.3% of the patients with residual stone fragments after standard PCNL for large burden kidney stones. The main site of infundibulum stricture after standard PCNL is the infundibulum of the entry calyx.

ABSTRACT Purpose: To describe our experience in the management of retained encrusted ureteral stents using a single session combined endourological approach. Materials and Methods: Patients with retained encrusted ureteral stents who had been submitted to a single session combined endourological approach from June 2010 to June 2018 were prospectively evaluated. Patients were divided according to the Forgotten-Encrusted-Calcified (FECal) classification. The stone burden, surgical intervention, number of interventions until stone free status, operation time, hospital stay, complications, stone analysis, and stone-free rate were compared between groups. ANOVA was used to compare numerical variables, and the Mann-Whitney or Chi-square test to compare categorical variables between groups. Results: We evaluated 50 patients with a mean follow-up of 2.9±1.4 years (mean±SD). The groups were comparable in terms of age, sex, laterality, BMI, comorbidities, ASA, reason for stent passage, and indwelling time. The stone burden was higher for grades IV and V (p=0.027). Percutaneous nephrolithotomy was the most common procedure (p=0.004) for grades IV and V. The number of procedures until the patients were stone-free was 1.92±1.40, and the hospital stay (4.2±2.5 days), complications (22%), and stone analysis (66% calcium oxalate) were similar between groups. The stone-free rate was lower in grades III to V (60%, 54.5%, and 50%). Conclusions: The endoscopic combined approach in the supine position is a safe and feasible technique that allows removal of retained and encrusted stents in a single procedure. The FECal classification seems to be useful for surgical planning.

Resumo Contexto e objetivo: Cálculos de fosfato de amônio e magnésio (FAM), também conhecidos como cálculos de estruvita, estão associados à infecção urinária e ao comprometimento da unidade renal. O objetivo deste estudo é avaliar os fatores de risco metabólico-urinários para recorrência de cálculos renais em pacientes submetidos à nefrectomia devido a cálculo de FAM. Métodos: Revisamos retrospectivamente os prontuários de pacientes > 18 anos submetidos à nefrectomia total devido a cálculos de FAM puro e cálculos de oxalato de cálcio puro (OxCa) de julho de 2006 a julho de 2016. Os parâmetros metabólicos urinários foram avaliados através de exames de urina de 24 horas ≥ 3 meses após a nefrectomia. Os parâmetros metabólicos urinários e um novo evento relacionado à litíase foram comparados. Resultados: Vinte e oito e 39 pacientes foram incluídos nos grupos FAM e OxCa, respectivamente. As anormalidades em amostras de urina de 24 horas foram similares entre os grupos. A hipercalciúria ocorreu em 7,1 e 10,3% dos pacientes nos grupos FAM e OxCa, respectivamente (p = 0,66), enquanto a hipocitratúria esteve presente em 65,2 e 59,0% dos pacientes nos grupos FAM e OxCa, respectivamente (p = 0,41). Nenhuma diferença significativa em novos eventos foi encontrada entre os grupos FAM e OxCa (17,9 vs. 23,1%, respectivamente; p = 0,60). Conclusão: Uma avaliação de urina de 24 horas deve ser oferecida aos pacientes submetidos à nefrectomia devido a cálculos de FAM puro, a fim de detectar risco metabólico, melhorar o tratamento e prevenir a recorrência de cálculos.

Abstract Background and objective: Magnesium ammonium phosphate stones (MAP), also known as struvite stones, are associated with urinary infection and impairment of renal unit. The aim of this study is to evaluate the urinary metabolic risk factors for recurrence of renal calculi in patients submitted to nephrectomy due to MAP stones. Methods: We retrospectively reviewed the charts of patients > 18 years old submitted to total nephrectomy due to pure MAP stones and pure calcium oxalate (CaOx) stones from July 2006 to July 2016. Urinary metabolic parameters were assessed through 24-hour urine exams ≥ 3 months after nephrectomy. Urinary metabolic parameters and new event related to lithiasis were compared. Results: Twenty-eight and 39 patients were included in MAP and CaOx group, respectively. Abnormalities in 24-hour urine samples were similar between groups. Hypercalciuria occurred in 7.1 and 10.3% of patients in MAP and CaOx group, respectively (p = 0.66), whereas hypocitraturia was present in 65.2 and 59.0% of patients with MAP and CaOx group, respectively (p = 0.41). No significant difference in new events was found between MAP and CaOx groups (17.9 vs. 23.1%, respectively; p = 0.60). Conclusion: A 24-hour urine evaluation should be offered to patients submitted to nephrectomy due to pure MAP stones in order to detect metabolic risk, improve treatment, and prevent stone recurrence.

Resumo Objetivo: Demonstrar as principais complicações hemorrágicas após nefrolitotripsia percutânea, bem como os resultados após o tratamento por embolização arterial transcateter (EAT) em um centro de radiologia intervencionista. Materiais e Métodos: Coleta e análise de dados retrospectivos de pacientes submetidos a EAT por complicações hemorrágicas após nefrolitotripsia percutânea. Resultados: O sintoma mais comum foi hematúria macroscópica, presente em cinco pacientes no momento da readmissão ao pronto-socorro, e nestes pacientes identificamos três pseudoaneurismas isolados, dois casos de combinação de pseudoaneurisma e sangramento ativo (hematoma perirrenal) e um caso de associação de pseudoaneurisma e fístula arteriocalicinal. Fístula arteriovenosa foi diagnosticada em três pacientes, não sendo observada em associação com outras lesões vasculares. Não identificamos fístula arteriocalicinal isolada, somente associada a pseudoaneurisma. Cinco pacientes foram submetidos a embolização por micromolas 6 × 15 mm e 6 × 20 mm. Quatro pacientes foram submetidos a embolização por Histoacryl e Lipiodol. Não observamos complicações pela angiotomografia computadorizada de controle. Conclusão: A angiotomografia computadorizada apresenta alta acurácia diagnóstica e guarnece o radiologista intervencionista de dados para um planejamento terapêutico individualizado. EAT é um procedimento seguro e eficaz e pode ser utilizado como primeira linha para o tratamento de complicações hemorrágicas resultantes de procedimentos percutâneos renais.

Abstract Objective: To identify the main hemorrhagic complications after percutaneous nephrolithotomy, as well as the results obtained with transcatheter arterial embolization (TAE) at an interventional radiology center. Materials and Methods: This was a retrospective analysis of patients undergoing TAE for the treatment of hemorrhagic complications after percutaneous nephrolithotomy. All patients underwent computed tomography angiography (CTA). Results: We evaluated a total of nine patients. At emergency department readmission, the most common symptom was macroscopic hematuria, which was seen in five patients. Three patients had an isolated pseudoaneurysm, two had a pseudoaneurysm together with active bleeding (perirenal hematoma), and one had a pseudoaneurysm together with arteriocalyceal fistula. Arteriovenous fistula was diagnosed in three patients and was not seen in combination with other vascular lesions. We did not identify arteriocalyceal fistula in isolation. Five patients underwent TAE with 6 × 15 mm and 6 × 20 mm microcoils. Four patients underwent TAE with n-butyl-2-cyanoacrylate and ethiodized oil. Follow-up CTAs revealed no complications. Conclusion: Because of its high diagnostic accuracy, CTA provides the interventional radiologist with valuable data for individualized therapeutic planning. The TAE procedure is safe and effective. It can therefore be used as a first-line treatment for hemorrhagic complications resulting from percutaneous renal procedures.

ABSTRACT Objectives Measurements of stone features may vary according to the non-contrast computed tomography (NCCT) technique. Using magnified bone window is the most accurate method to measure urinary stones. Possible differences between stone measurements in different NCCT windows have not been evaluated in stones located in the kidney. The aim of this study is to compare measurements of kidney stone features between NCCT bone and soft tissue windows in patients submitted to retrograde intrarenal surgery (RIRS). Materials and Methods Preoperative and 90th postoperative day NCCT were performed in 92 consecutive symptomatic adult patients (115 renal units) with kidney stones between 5 mm to 20 mm (< 15 mm in the lower calyx) treated by RIRS. NCCT were evaluated in the magnified bone window and soft tissue window in three axes in a different time by a single radiologist blinded for the measurements of the NCCT other method. Results Stone largest size (7.92±3.81 vs. 9.13±4.08; mm), volume (435.5±472.7 vs. 683.1±665.0; mm3) and density (989.4±330.2 vs. 893.0±324.6; HU) differed between bone and soft-tissue windows, respectively (p<0.0001) 5.2% of the renal units (6/115) were reclassified from residual fragments > 2 mm on soft tissue window to 0-2 mm on bone window. Conclusion Kidney stone measurements vary according to NCCT window. Measurements in soft tissue window NCCT of stone diameter and volume are larger and stone density is lesser than in bone window. These differences may have impact on clinical decisions.

ABSTRACT Purpose: To compare the outcomes of percutaneous nephrolithotomy (PCNL) performed in the prone position (PRON) and in three variations of the supine position. Materials and Methods: We performed a retrospective analysis of patients that underwent PCNL at our institution from June 2011 to October 2016 in PRON and in three variations of the supine position: complete supine (COMPSUP), original Valdivia (VALD), and Galdakao - modified Valdivia (GALD). All patients had a complete pre - operative evaluation, including computed tomography (CT). Success was defined as the absence of residual fragments larger than 4 mm on the first post - operative day CT. Results: We analyzed 393 PCNLs: 100 in COMPSUP, 94 in VALD, 100 in GALD, and 99 in PRON. The overall success rate was 50.9% and was similar among groups (p = 0.428). There were no differences between groups in the number of punctures, stone - free rate, frequency of blood transfusions, drop in hemoglobin level, length of hospital stay, and severe complications (Clavien ≥ 3). COMPSUP had a significantly lower operative time than the other positions. COMPSUP had lower fluoroscopy time than VALD. Conclusion: Patient positioning in PCNL does not seem to impact the rates of success or severe complications. However, COMPSUP is associated with a shorter surgical time than the other positions.

ABSTRACT Objective: To show a video of a complete supine Percutaneous Nephrolithotomy (csPCNL) performed for the treatment of a staghorn calculus, from the surgeon's point of view. The procedure was recorded with a GoPro® camera, demonstrating the ten essential steps for a successful procedure. Materials and methods: The patient was a 38 years-old woman with 2.4cm of left kidney lower pole stone burden who presented with 3 months of lumbar pain and recurrent urinary tract infections. She had a previous diagnosis of polycystic kidney disease and chronic renal failure stage 2. CT scan showed two 1.2cm stones in the lower pole (Guy's Stone Score 2). She had a previous ipsilateral double J insertion due to an obstructive pyelonephritis. The csPCNL was uneventful with a single access in the lower pole. The surgeon had a Full HD GoPro Hero 4 Session® camera mounted on his head, controlled by the surgical team with a remote control. All of the mains steps were recorded. Informed consent was obtained prior to the procedure. Results: The surgical time was 90 minutes. Hemoglobin drop was 0.5g/dL. A post-operative CT scan was stone-free. The patient was discharged 36 hours after surgery. The camera worked properly and didn't cause pain or muscle discomfort to the surgeon. The quality of the recorded movie was excellent. Conclusion: GoPro® camera proved to be a very interesting tool to document surgeries without interfering with the procedure and with great educational potential. More studies should be conducted to evaluate the role of this equipment.

ABSTRACT Purpose: To evaluate the impact of the patient position on the outcomes of PCNL among patients with complex renal stones. Material and Methods: From July 2011 to July 2014, we collected prospective data of consecutive patients who underwent PCNL. We included all patients with complex stones (Guy's Stone Score 3 or 4 (GSS) based on a CT scan) and divided them based on the position used during PCNL (prone or supine). The variables analyzed were gender, age, body mass index, ASA score, stone diameter, GSS, number of punctures, calyx puncture site, intercostal access and patient positioning. Complications were graded according to the modified-Clavien Classification. Success was considered if fragments ≤ 4mm were observed on the first postoperative day CT scan. Results: We analyzed 240 (46.4%) of 517 PCNL performed during the study period that were classified as GGS 3-4. Regarding patient positions, 21.2% were prone and 79.8% were supine. Both groups were comparable, although intercostal access was more common in prone cases (25.5% vs 10.5%; p=0.01). The success rates, complications, blood transfusions and surgical times were similar for both groups; however, there were significantly more visceral injuries (10.3% vs 2.6%; p=0.046) and sepsis (7.8% vs 2.1%; p=0.042) in prone cases. Conclusion: Supine or prone position were equally suitable for PCNL with complex stones and did not impact the success rates. However, supine position was associated with fewer sepsis cases and visceral injuries.

ABSTRACT Introduction To present the current practice patterns on percutaneous nephrolithotomy (PCNL) in a developing country. Materials and Methods A survey was offered to Brazilian urologists during the II International Endourology Symposium held in Sao Paulo, in 2015. The first seven questions were related to demographic data while the 20 remaining were directed to urologists who performed PCNL. Results From 250 participants, 100 replied to the survey, 81% performed PCNL and 60.4% of performers had been in practice for less than 15 years. Eighty-one percent were trained in the prone position and 64% in supine. PCNL was learned during the residency in 66.7% and 2.5% had fellowship training. Prone position was the preferred decubitus for simple or complex calculi, though for obese patients there was no difference. Younger surgeons prefer supine while older surgeons prefer prone. The access was obtained by the surgeon in all cases, 96.3% use fluoroscopy and 3.7% prefer ultrasonography. Forty-seven percent use ultrasonic lithotripters and 4.1% laser. For kidney drainage, 71.6% place a nephrostomy tube. Double J stent is left in 77%. The postoperative image method was CT for 50%. Colonic injury was reported by 25%, predominantly in the senior group without statistically difference between positions. Conclusions From a selected group of urologists, we observe that Brazilian urologists usually gain their own access for PCNL guided by fluoroscopy. They predominantly prefer the prone position, use fascial dilators, ultrasonic lithotripters and place a nephrostomy tube when exiting the kidney. Fellowship programs, ultrasonography, flexible nephoscopy and tubeless procedures could be encouraged.

PurposeWe developed a stereotactic device to guide the puncture for percutaneous nephrolithotripsy, which uses the distance from the target calyx to its perpendicular point on skin (SCD) to calculate the needle´s entry angle. This study seeks to validate the use of measurements obtained by ultrasound (US) and computerized tomography (CT) for needle´s entry angle calculation and to study factors that may interfere in this procedure.Materials and MethodsHeight, weight, abdominal circumference, CT of the urinary tract in dorsal decubitus (DD) and ventral decubitus (VD), and US of the kidneys in VD were obtained from thirty-five renal calculi patients. SCD obtained were compared and correlated with body-mass index (BMI).ResultsBMI was 28.66 ± 4.6 Kg/m2. SCD on CT in DD was 8.40 ± 2.06cm, in VD was 8.32 ± 1.95cm, in US was 6.74 ± 1.68cm. SCD measured by US and CT were statistically different (p < 0.001), whereas between CT in DD and VD were not. SCD of the lower calyx presented moderate correlation with BMI.ConclusionSCD obtained by CT in ventral and dorsal decubitus may be used for calculation of the needle´s entry angle. SCD obtained by US cannot be used. A rule for the correlation between BMI and the SCD could not be determined.