Minimally Invasive Percutaneous Nephrolithotomy Research Articles

The Vortex Effect in Minimally Invasive Percutaneous Nephrolithotomy

To describe the physical principles of the vortex effect to better understand its applicability in minimally invasive percutaneous nephrolithotomy (MIP) procedures. Two acrylic phantom models were built based on the cross-sectional area (CSA) ratio of a MIP nephroscope and access sheaths (15/16F and 21/22F MIP-M™, Karl Storz®). The nephroscope phantom was 10mm in diameter. The access sheaths had diameters of 14mm (CSA ratio: 0.69) and 20mm (CSA ratio: 0.30). The models were adapted to generate hydrolysis, and hydrogen bubbles enhanced flow visualization on a green laser background. After calibration, the experimental flow rate was set to 12.0mL/s. Three 30-second trials assessing the flow were performed with each model. Computational fluid dynamic simulations were completed to determine the speed and pressure profiles. In both models, as the incoming fluid from the nephroscope phantom attempted to move toward the collecting system, a stagnation point (SP) was demonstrated. No fluid entered the collecting system phantom. Utilizing the 14mm-sheath, we observed a random generation of several vortices and a pressure gradient (PG) of 114.4N/m2 between the nephroscope's tip and SP. In contrast, examining the 20mm-sheath revealed a significantly smaller PG (19.4N/m2) and no noticeable vortices were noted. The speed of the fluid and equipment geometry regulate the PG and the vortices field, which are responsible for the production of the vortex effect. Considering the same flow rate, a higher ratio between the CSA of the nephroscope and access sheath results in improved efficacy of the vortex effect.

Comparative efficacy between retrograde intrarenal surgery with vacuum-assisted ureteral access sheath and minimally invasive percutaneous nephrolithotomy for 1-2 cm infectious upper ureteral stones: a prospective, randomized controlled study.

To observe the efficacy and safety of retrograde intrarenal surgery combined with vacuum-assisted ureteral access sheath (V-UAS) and minimally invasive percutaneous nephrolithotomy (MPCNL) in patients with 1-2 cm infectious upper ureteral stone. A total of 173 patients with 1-2 cm infectious upper ureteral stone were prospectively randomized into two groups. Eighty-six in the V-UAS group and 87 cases as control in the MPCNL group. The SFRs at different times (Postoperative 1 day, 2nd week and 4th week) was considered as the primary outcome of the study. The secondary end points were operative time, postoperative hospital stay and operative complications. There was no obvious difference between two groups in patients' demographics and preoperative clinical characteristics (all P > 0.05). Postoperative data showed that the SFR at postoperative 1 day in the V-UAS group was significantly lower than that in the MPCNL group (73.2% vs. 86.2%, P = 0.034). However, there was no statistical significance between two groups in SFRs during postoperative 2 weeks and 4 weeks (All P > 0.05). The levels of WBC, CRP and PCT were all significant lower in the V-UAS group than those in the MPCNL group at the postoperative 24 h and 48 h (all P < 0.05). Postoperative complications included fever (≥38.5°C), bleeding, pain and urosepsis. In terms of the rates of fever, pain and urosepsis, MPCNL group were all significantly higher than those in the V-UAS group (10.3 vs. 2.4%, P = 0.031; 14.9 vs. 2.4%, P = 0.003; 4.6 vs. 0.0%, P = 0.044; respectively). No significant difference was found between two groups in bleeding. Meanwhile, postoperative hospital stay in the V-UAS group was more shorten than that in the MPCNL group (3.7 vs. 5.9 days, P < 0.001). Our study showed that RIRS with V-UAS, a new partnership to treat 1-2 cm infectious upper ureteral stones, was satisfying as it achieved a high SFR rate and a low rate of infectious complications. This method was safe and reproducible in clinical practice.

V02-01 THE VORTEX EFFECT IN MINI-PCNL: IMPROVED UNDERSTANDING WITH A PHANTOM MODEL &amp; COMPUTATIONAL FLUID DYNAMICS

You have accessJournal of UrologyCME1 Apr 2023V02-01 THE VORTEX EFFECT IN MINI-PCNL: IMPROVED UNDERSTANDING WITH A PHANTOM MODEL & COMPUTATIONAL FLUID DYNAMICS Willian Ito, Dillon Prokop, Crystal Valadon, Bristol Whiles, Donald Neff, David Duchene, and Wilson Molina Willian ItoWillian Ito More articles by this author , Dillon ProkopDillon Prokop More articles by this author , Crystal ValadonCrystal Valadon More articles by this author , Bristol WhilesBristol Whiles More articles by this author , Donald NeffDonald Neff More articles by this author , David DucheneDavid Duchene More articles by this author , and Wilson MolinaWilson Molina More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003232.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Minimally invasive percutaneous nephrolithotomy (MIP) was initially discredited with assumptions of difficult stone fragment retrieval because of the equipment’s smaller size. However, in 2008 Nagele et al. described a hydrodynamic phenomenon that allowed stone retrieval without the aid of endoscopic tools. This study aims to describe the physical principles of the “vortex effect” to better understand its applicability in MIP procedures. METHODS: Two acrylic phantom models were built based on the cross-sectional area (CSA) ratio of a MIP nephroscope and access sheaths (15/16F and 21/22F MIP-M™, Karl Storz®). The nephroscope phantom was 10 mm in diameter. The access sheaths had diameters of 14 mm (CSA ratio: 0.69) and 20 mm (CSA ratio: 0.30). The models were adapted to generate hydrolysis, and hydrogen bubbles enhanced flow visualization on a green laser background. After calibration, the experimental flow rate was set to 12.0 mL/sec. Three 30-second trials assessing the flow were performed with each model. Computational fluid dynamic simulations (CFD) were completed to determine the speed and pressure profiles. RESULTS: In both models, as the incoming fluid from the nephroscope phantom unsuccessfully attempted to move toward the collecting system, a stagnation point (SP) was demonstrated. No fluid entered the collecting system phantom. Utilizing the 14 mm sheath, we observed a random generation of several vortices and a pressure gradient (PG) of 114.4 N/m2 between the nephroscope’s tip and SP. When the 20 mm sheath was examined, a significantly smaller PG (19.4 N/m2) and no noticeable vortices were noted. CONCLUSIONS: The speed of the fluid and equipment geometry regulate the pressure gradient and the vortices field, which are responsible for the production of the vortex effect. Considering the same flow rate, a higher ratio between the cross-sectional area of the nephroscope and access sheath results in improved efficiency of the vortex. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e168 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Willian Ito More articles by this author Dillon Prokop More articles by this author Crystal Valadon More articles by this author Bristol Whiles More articles by this author Donald Neff More articles by this author David Duchene More articles by this author Wilson Molina More articles by this author Expand All Advertisement PDF downloadLoading ...

Surgical parameters related to excessive intrarenal pressure during minimally-invasive percutaneous nephrolithotomy in the supine position: A prospective observational clinical study

Surgical parameters related to excessive intrarenal pressure during minimally-invasive percutaneous nephrolithotomy in the supine position: A prospective observational clinical study

Effects of severe hydronephrosis on surgical outcomes of minimally invasive percutaneous nephrolithotomy (MPCNL).

The impact of severe hydronephrosis on the outcomes of minimally invasive percutaneous nephrolithotomy (MPCNL) remains controversial; it is still a subject well worth exploration. To investigate the effects of severe hydronephrosis on surgical outcomes of MPCNL, especially on operative time (OT) and stone-free rate (SFR). In total, 301 patients who underwent MPCNL were included in this study and divided into 4 groups according to the degree of hydronephrosis (nil, mild, moderate, and severe hydronephrosis, respectively). Univariate analyses and multivariate logistic analyses were used to determine the risk factors affecting OT and SFR. Patients with severe hydronephrosis had a longer OT (p < 0.001), a decreased SFR (p < 0.001), and a higher postoperative haemoglobin drop and blood transfusion rate compared to the other 3 cohorts (p = 0.011 and p = 0.043, respectively). Univariate analyses determined that severe hydronephrosis, calyx for access, stone location, stone type, stone size, and number of tracts significantly correlated with OT, while severe hydronephrosis, stone location, stone type, and stone size showed a strong association with SFR (all p < 0.05). Multivariate analyses further identified that severe hydronephrosis (OR = 3.496, p = 0.013), stone location (≥ 4 calyces: OR = 3.024, p = 0.017), stone type (staghorn: OR = 5.204, p = 0.002), and stone size (≥ 1600 mm2: OR = 12.669, p < 0.001; 800-1599 mm2: OR = 5.194, p < 0.001) were significant risk factors affecting OT, while SFR was independently influenced by stone type (staghorn: OR = 4.377, p = 0.039; multiple: OR = 3.778, p = 0.044), stone location (≥ 4 calyces: OR = 4.413, p = 0.020; 2-3 calyces: OR = 3.617, p = 0.034), and severe hydronephrosis (OR = 7.093, p = 0.001). Severe hydronephrosis is a significant risk factor that can lead to longer OT and lower SFR, and correlates with increased risk of bleeding and blood transfusion rate in some cases during MPCNL. Accordingly, severe hydronephrosis is an influential factor that should not be ignored when performing MPCNL.

Potential Risk of Calcified Nanoparticles for Recurrent Urinary Tract Infection after Minimally Invasive Percutaneous Nephrolithotomy for Renal Calculi.

Among urolithiasis, urolithiasis is a more extensive and difficult to treat disease. In recent years, with the development of endoscopic equipment and related surgical methods, a new treatment, namely minimally invasive percutaneous nephrolithotomy, appears and is widely used in the treatment of renal calculi. It has been developed for more than 50 years since its appearance. Its advantages are a high stone clearance rate, small surgical trauma, fewer intraoperative and postoperative complications, and a short recovery time for postoperative patients. It is widely used in clinical treatment. The purpose of this paper is to study the potential risk factors of recurrence and the possibility of urinary tract infection in patients with renal calculi after minimally invasive percutaneous nephrolithotomy (MPCNL) with calcified nanoparticles, so as to obtain correct nursing knowledge and reduce recurrence and infection. In order to explore the renal calculi caused by calcified nanoparticles (CNPs), we established a rat model of renal calculi, injected CNPs into rats, collected experimental samples after a specified time, and determined NGAL, OPN and MCP-1 by enzyme-linked immunosorbent assay (ELISA) and compared them with the formation of crystallization. In the study of the possible influencing factors of septic shock after PCNL, we established a multivariate regression analysis and model, used statistical methods and professional statistical software, and used the method of classified data analysis to find out the influencing factors. After the experiment, we found that positive urine culture (P < 0.05) and preoperative urinary tract infection (P < 0.05) were significant influencing factors, and the total accuracy was 99.2%. At the same time, it is concluded that calcium nanoparticles can promote the retention, adhesion and aggregation of calcium salt crystals in the kidney, and then lead to the formation of stones.

Factors Affecting Residual Stone Rate, Operative Duration, and Complications in Patients Undergoing Minimally Invasive Percutaneous Nephrolithotomy.

Background and objectives: Although minimally invasive percutaneous nephrolithotomy (MPCNL) has demonstrated its efficacy, complete stone clearance was not always achieved, necessitating a second procedure. The purpose of this study was to evaluate factors associated with residual stone rate, operative duration, complications, and hospital stay, in order to develop algorithms for pre-operative prognosis and planning. Materials and Methods: This retrospective study involved 163 Bulgarian patients who underwent MPCNL with Holmium: YAG lithotripsy for the treatment of kidney stones. Patients were considered stone-free if no visible fragments (<3 mm) were found on nephroscopy at the end of the procedure, as well as on postoperative X-ray and abdominal ultrasound on the first postoperative day. Results: Immediate postoperative stone-free outcome was attained for 83.43% of the patients (136/163). Residuals were associated with staghorn stones (OR = 72.48, 95% CI: 5.76 to 91.81); stones in two locations (OR = 21.91, 95% CI: 4.15 to 137.56); larger stone size (OR = 1.12, 95% CI: 1.006 to 1.25); and higher density (OR = 1.03, 95% CI:1.005 to 1.06). The overall categorization accuracy for these factors was 93.80%, AUC = 0.971 (95% CI: 0.932 to 0.991), 89.71% sensitivity, and 96.30% specificity. Predictors of prolonged operative duration were staghorn stones and volume, R-square (adj.) = 39.00%, p < 0.001. Longer hospitalization was predicted for patients with hydronephrosis and staghorn stones, R-square (adj.) = 6.82%, p = 0.003. Post-operative complications were rare, predominantly of Clavien-Dindo Grade 1, and were more frequent in patients with hydronephrosis. We did not find a link between their occurrence and the outcome of MPCNL. Conclusions: Staghorn stones and stones in more than one location showed the strongest association with residual stone rate. Staghorn stones and larger volume were linked with a longer operative duration. Hydronephrosis increased the risk of complications and longer hospitalization.

Suctioning Flexible Ureteroscopy with Automatic Control of Renal Pelvic Pressure versus Mini PCNL for the Treatment of 2–3-cm Kidney Stones in Patients with a Solitary Kidney

Objective: The aim of the study was to compare the treatment outcomes between suctioning flexible ureteroscopic lithotomy (SF-URL) with automatic control of renal pelvic pressure and minimally invasive percutaneous nephrolithotomy (MPCNL) for the management of 2–3-cm renal stones in patients with a solitary kidney. Materials and Methods: A total of 127 patients with a solitary kidney who underwent SF-URL (n = 57) or MPCNL (n = 70) for large renal stones (>2 cm) between June 2015 and October 2020 were consecutively analyzed. The stone characteristics, operative times, stone-free rate (SFR), hospital stays, and incidences of complications were compared. Results: There was a significantly shorter operative time with MPCNL than with SF-URL (43.4 ± 18.9 min vs. 61.8 ± 21.1 min, p = 0.012). SFR at 30 days were 80.7% (46/57) and 90.0% (63/70) for SF-URL and MPCNL, respectively (p > 0.05). The SFR at the 3-month follow-up was comparable in both groups (91.2% vs. 95.7%, p > 0.05). The hemoglobin decline value, hospital stay, serum cystatin C, and percentage of patients requiring blood transfusions in the SF-URL group were obviously better than those in the MPCNL group: (0.8 ± 0.4) versus (3.9 ± 2.7) g/dL (p = 0.007), (3.6 ± 1.5) versus (6.9 ± 3.1) days (p = 0.013), (1.02 ± 0.48) versus (2.54 ± 0.69) mg/L (p = 0.011), and 0 (0.0%) versus 7 (10.0%) (p = 0.016), respectively. The percentages of patients with thrombosis and perirenal hematoma in the MPCNL group were higher than those in the SF-URL group, but the difference was not statistically significant (p > 0.05). Conclusion: For the treatment of 2–3-cm renal stones in patients with a solitary kidney, both SF-URL and MPCNL are effective. MPCNL has the advantage of a shorter operation time. However, SF-URL is characterized by less bleeding, shorter hospital stay, and less damage to kidney function.

Application of Clavien-Dindo Classification System for Complications of Minimally Invasive Percutaneous Nephrolithotomy.

Objective To investigate the clinical applications of the Clavien–Dindo classification system (CDCS) in the assessment of perioperative complications in minimally invasive percutaneous nephrolithotomy (MPCNL). Methods Totally, 390 patients with renal stones in our hospital from March 2015 to March 2020 were included for this study and then were divided into observation group (complication group, 78 cases) and control group (noncomplication group, 312 cases) according to the incidence of perioperative complications in CDCS. Single factor analysis and multivariate logistic regression analysis were used to analyze the risk factors of the perioperative complications of MPCNL. Results The total incidence of complication in the 390 cases with MPCNL was 20.00% (78 cases) according to CDCS, among which the incidence of complications at grades I, II, III, IV, and V was 6.92% (27 cases), 8.21% (32 cases), 2.82% (11 cases), 1.79% (7 cases), and 0.26% (1 case), respectively. The proportion of patients, that aged >60 years, complicated with comorbidities, sophisticated calculi, the preoperative albumin level (<35 g/L), the operation time (>180 minutes), intraoperative bleeding volume (>300 mL), and hospitalization time (>7 days) in the observation group was significantly higher than that in the control group ((75.64% vs. 61.86%, 38.46% vs. 24.36%, 83.33% vs. 69.55%, 83.33% vs. 69.55%, 70.51% vs. 30.76%, 53.85% vs. 36.54%, and 60.26% vs. 43.27%), all P < 0.05). Multivariate logistic regression analysis showed that gender, associated comorbidities, preoperative albumin level, calculus complexity, operation time, and intraoperative bleeding volume (>300 mL) were correlated with the occurrence of complications (P ≤ 0.001, 0.001, 0.001, 0.001, 0.003, and 0.001 respectively). Conclusion The CDCS can give standard and more comparative criteria for the assessment of perioperative complications, which will provide reference data for reducing complications and ensuring safety profiles in these high-risk patients.

Comparison of vacuum-assisted sheaths and normal sheaths in minimally invasive percutaneous nephrolithotomy: a systematic review and meta-analysis

BackgroundA systematic review and meta-analysis was conducted to compare the safety and efficacy of vacuum-assisted sheaths and conventional sheaths in minimally invasive percutaneous nephrolithotomy (MPCNL) in the treatment of nephrolithiasis.MethodsPubMed, Web of Science, Embase, EBSCO, and Cochrane Library databases (updated March 2021) were used to search for studies assessing the effect of vacuum-assisted sheaths in patients who underwent MPCNL. The search strategy and study selection processes were implemented in accordance with the PRISMA statement.ResultThree randomized controlled trials and two case-controlled trials that satisfied the inclusion criteria were enrolled in this meta-analysis. Overall, the stone-free rate (SFR) in patients who underwent vacuum-assisted sheaths was significantly higher than that in patients who underwent conventional sheaths (RR 1.23, 95% CI 1.04, 1.46, P = 0.02), with significant heterogeneity among the studies (I2 = 72%, P = 0.03). In terms of the outcome of complications, vacuum-assisted sheath could bring a benefit to the postoperative infection rate (RR 0.48, 95% CI 0.33, 0.70, P < 0.00001) with insignificant heterogeneity among the studies (I2 = 0%, P = 0.68). There was no significant difference in the blood transfusion rate (RR 0.35, 95% CI 0.07, 1.73, P = 0.17), with significant heterogeneity (I2 = 66%, P = 0.35). Three studies contained operative time data, and the results indicated that the vacuum-assisted sheath led to a shorter operative time (MD = − 15.74; 95% CI − 1944, − 12.04, P < 0.00001) with insignificant heterogeneity (I2 = 0%, P = 0.91).ConclusionThe application of a vacuum-assisted sheath in MPCNL improves the safety and efficiency compared to the conventional sheath. A vacuum-assisted sheath significantly increases the SFR while reducing operative time and postoperative infection.

Pooled-analysis of efficacy and safety of minimally invasive versus standard percutaneous nephrolithotomy.

Background:This study aimed to assess the efficacy and safety of minimally invasive percutaneous nephrolithotomy (MPCNL) versus standard percutaneous nephrolithotomy in patients with renal and upper ureteric stones.Methods:We conducted a pooled analysis on randomized controlled trials (RCTs). The eligible RCTs were selected from the following databases: MEDLINE, Embase, Web of Science, and the Cochrane Library. The reference lists of retrieved studies were also investigated.Results:Our analysis included 10 RCTs with 1612 patients. Pooled data from 10 RCTs revealed the following: stone-free rate (odds ratio = 1.46, 95% confidence interval (CI) [1.12,1.88], P = .004), operative time (mean difference [MD] = 4.10, 95% CI [–1.37,9.56], P = .14), length of hospital stay (MD = –15.31, 95% CI [–29.43,–1.19], P = .03), hemoglobin decrease (MD = –0.86, 95% CI [–1.19,–0.53], P < .00001), postoperative fever (MD = 0.83, 95% CI [0.49,1.40], P = .49), and urine leakage (MD = 0.59, 95% CI [0.25,1.37], P = .22). Besides, we performed sub-group analysis based on vacuum suction effect and multiple kidney stones. For vacuum suction effect, it revealed the following: stone-free rate in vacuum suction group (P = .007) and in non-vacuum suction group (P = .19). Operative time in vacuum suction group (P = .89), non-vacuum suction group (P = .16). Postoperative fever in vacuum suction group (P = .49), non-vacuum suction group (P = .85).Conclusion:This pooled analysis indicated that MPCNL was a safe and effective method for treating renal stones compared with standard percutaneous nephrolithotomy. Besides, the vacuum suction effect in MPCNL played a more important role. When it comes to multiple or staghorn stones, the longer operative time in MPCNL could not be ignored.

Clinical Comparison of Mini-Percutaneous Nephrolithotomy with Vacuum Cleaner Effect or with a Vacuum-Assisted Access Sheath: A Single-Center Experience

Purpose: To compare outcomes of two different miniaturized percutaneous nephrolithotomy (PCNL) techniques: minimally invasive PCNL (MIP) with the vacuum cleaner effect and vacuum-assisted mini-PCNL (vmPCNL). Materials and Methods: Data from 104 (66.7%) patients who underwent vmPCNL and 52 (33.3%) patients who underwent MIP at a single tertiary referral academic center between January 2016 and December 2019 were analyzed. Patient demographics and peri- and postoperative data were recorded, and propensity score matching was performed. Descriptive statistics and linear regression models were used to identify variables associated with operative time (OT) and patient effective dose. Logistic regression analyses were used to identify factors associated with infectious complications and stone-free (SF) status. Results: Patient demographics and stone characteristics were comparable between groups. vmPCNL was associated with shorter OT (p < 0.001), fluoroscopy time, and patient effective dose (4.2 mSv vs 7.9 mSv; p < 0.001). A higher rate of infectious complications was found in the MIP group (25.0% vs 7.7%, p < 0.01). Linear regression analysis showed that stone volume, multiple stones, and MIP procedure (all p values ≤0.02) were associated with longer OT. Similarly, OT and the MIP procedure (p ≤ 0.02) were associated with higher patient effective dose. Logistic regression analysis revealed that the stone volume, positive preoperative bladder urine culture, and MIP procedure (all p values ≤0.02) were associated with postoperative infectious complications. vmPCNL was not associated with the SF rate. Conclusions: Mini-PCNL performed with continuous active suction is associated with lower rates of infectious complications, shorter OT, and lower patient effective dose than MIP.

Stone Localization Is Pivotal for the Success of Percutaneous Nephrolithotomy

Objective: The objective of this study was to predict computed tomography (CT)-controlled treatment success after minimally invasive percutaneous nephrolithotomy (Mini-PCNL). Patients and Methods: We relied on retrospective single institutional data from 92 kidney stone patients treated with Mini-PCNL. Residual stones after treatment were evaluated by post-Mini-PCNL CT scans. Stone-free status was defined as clinically insignificant residual stones ≤3 mm after surgery. Multivariable logistic regression analyses predicted stone-free status after Mini-PCNL. Results: Overall, 53 (57.6%) patients achieved stone-free status after Mini-PCNL treatment. In multivariable logistic regression analyses, stone localization was the strongest predictor for stone-free status after Mini-PCNL. Specifically, patients with exclusively pelvic stones were 7.1-fold more likely to achieve stone-free status than those patients with stones at multiple localizations (OR: 7.1; p = 0.005). Additionally, stone size represented a barrier for stone-free status (OR: 0.9; p = 0.03). Conclusions: Stone localization revealed the highest impact on treatment success after Mini-PCNL. Especially, those patients with exclusively pelvic stones were most likely to achieve stone-free status. Conversely, patients with multiple stone localizations were less likely to achieve stone-free status and need to be informed about higher risk of additional interventions after initial Mini-PCNL.

Minimally Invasive Percutaneous Nephrolithotomy: Initial North American Experience.

Introduction and Objectives: The goal of this study is to evaluate the outcomes in a cohort of patients who underwent minimally invasive percutaneous nephrolithotomy (MIP) at a single institution from 2017 to 2019. Methods: Sixty patients at a single institution with two different surgeons underwent MIP from 2017 to 2019. The MIP technique uses a proprietary nephroscope with a "vacuum" technique for stone evacuation. Patients were identified who had postoperative CT scan imaging available for direct review. A prospectively maintained database was queried along with retrospective chart review to evaluate the stone-free rate defined as no stones on CT imaging. Preoperative, intraoperative, and postoperative variables were analyzed including initial stone size, access type (fluoroscopic vs ultrasonic), access location, operative positioning (supine vs prone), operative time, and 60-day complications. Results: Forty-six of 60 patients had CT imaging postoperatively that were reviewable. Of these, 43% (n = 20) were stone free as defined by no identifiable fragments seen, 11% (n = 5) had residual fragments 0 to 2 mm, 7% (n = 3) had residual fragments 2 to 4 mm, and 39% (n = 18) had residual fragments >4 mm. Mean initial stone size was 21 mm (1.9-84 mm). Sixty percent (n = 28) of the patients were discharged the same day as surgery. Fifty-one percent (n = 24) of access was achieved through ultrasound alone. Seventeen percent of patients (n = 8) had a complication within 30 days of surgery. All complications were Clavien III or lower with unplanned return to operating room rate of 2% (n = 1). Conclusions: We present North America's first single institution analysis of MIP cases with acceptable outcomes comparable with both retrograde intrarenal surgery and standard percutaneous nephrolithotomy. The exact role of MIP in renal stone disease needs to be determined by future studies that critically assess their outcomes.

Miniaturization of PCNL; Necessity or What?

Objective: Now a days, percutaneous nephrolithotomy (PCNL) is the treatment of choice for retrieval of renal and proximal ureteral calculi. The primary goal of PCNL is to achieve stone free status while minimizing morbidity and complications. In recent years, the instruments used have been miniaturized in an effort to decrease morbidity associated with standard PCNL as well as increase the efficacy of stone removal. The aim of this study was to compare the safety and efficacy of PCNL using different tract size.&#x0D; Patients and Methods: This hospital based prospective interventional study was conducted on patients with 1 to 4 cm renal stones who underwent PCNL either by Mini or by Standard PCNL technique in Chattogram Medical College Hospital and different private hospitals in Chattogram from July 2016 to October 2018. Patients aged above 12 years of age, irrespective of gender with normal renal function were evaluated to compare stone clearance, access time, fluoroscopy time for access, total operative time, need for blood transfusion, postoperative hospital stay, postoperative pain, fever, urinary leakage and other complications between two groups. Those who had previous history of open renal surgery, active urinary tract infection, renal malformation, uncorrected coagulopathy and morbid obesity were excluded.&#x0D; Results: A total of 78 patients were enrolled consecutively for PCNL who were divided equally into two groups randomly for minimally invasive PCNL (Mini-PCNL) and Standard PCNL. The average stone size in mini-PCNL group was 2.59±0.89 cm, and 2.66±0.97 cm in standard-PCNL group (p=0.7). Mean tract size was 18.53 ± 1.29 F (16-20) and 26.11 ± 4.61 F (24-30) respectively with P value &amp;lt;0.001. In mini-PCNL operative time was significantly longer than that of standard PCNL with 112.11 ± 20.29 vs. 98.68± 19.75 minutes respectively with p=.004. Conversely, there was an advantage of mini-PCNL over the standard one in terms of a significantly reduced hemoglobin drop (0.5 ± 0.26 vs. 0.83 ± 0.32 gm%, p value 0.001) and hospital stay (2.18 ± 0.77 vs. 3.39 ± 1.10 days, p value= 0.001), respectively though there was no statistical difference in terms of stone clearance rates between two groups (86.84% vs. 92.11%, p=0.45). There was no statistical difference in terms of visual analogue scale (VAS) score (5.55±1.54 vs. 6.24±1.6) for pain perception. The complication rate of mini-PCNL had no significant difference with that of standard PCNL (10.52% vs 12.50%, p=0.72). No statistical difference was recorded in terms of postoperative fever (eŠ38C) between two groups (2 in each group, 5.2%, p=1 Blood transfusion requirement was much less in mini PCNL group (10.52% vs. 34.2%, p=0.01).&#x0D; Conclusion: In addition to minimal bleeding and excellent stone clearance, mini- PCNL has several features for which it should be considered as an alternative or adjunct tostandard PCNL, URS, and ESWL. These include safe supra-costal puncture, excellent access to nearly all calyces and upper ureter, less hospital stay and suitable for large stones also. Future studies should continue to refine methods to assess complexity and safety and to determine consensus on the use of mini- PCNL.&#x0D; Bangladesh Journal of Urology, Vol. 23, No. 1, January 2020 p.11-16

Minimally Invasive Percutaneous Nephrolithotomy with a Novel Vacuum-assisted Access Sheath for obstructive calculous pyonephrosis ：A Randomized Study.

To investigate the safetyandefficacyof Minimally Invasive Percutaneous Nephrolithotomy (MPCNL)combined with Vacuum-assisted Access Sheath in the treatment of obstructive calculous pyonephrosis. Seventy-six patients with obstructive calculous pyonephrosis, who were planned to receive MPCNL, were randomly divided into two groups. Group A was treated with Amplatz sheath combined with Cyberwand double probe ultrasound lithotripsy, and group B was treated with Vacuum-assisted Access Sheath (VAAS, ClearPetra, Well lead Medical) combined with holmium laser lithotripsy. The primary outcome was the operation successful rate. Other perioperative, and postoperative data such as operation time, stone free rate and complications were compared between groups. Single 20F access sheath was established in all cases. All patients underwent one-stage procedure. Compared with group A, group B had a higher initial stone-free rate (84.2% vs 63.1%, P= .037). The operation time of group B was 56.3 ± 19.83 min, significantly shorter than that of group A at 70.4 ± 14.83 min. The complication rate of B group was 15.8%, which was lower than that of group A (P= .035 ). Five patients (15.8 %) of group B had a postoperative fever (>38.5 ºC) (Clavien grade 2) that required additional antibiotics; whereas 8 patients (21.1 %) of group A (P= .361). There was no blood transfusion in group A, and one case in group B required transfusion. One-stage MPCNL combined with Vacuum-assisted Access Sheath and holmium laser lithotripsy is a simple, safe, effective, and ergonomically practical method for selected patients with obstructive calculous pyonephrosis.

Ultrasound-Guided Minimally Invasive Percutaneous Nephrolithotomy is Effective in the Management of Pediatric Upper Ureteral and Renal Stones

Aim To evaluate the outcome of ultrasound (US)-guided minimally invasive percutaneous nephrolithotomy (MPCNL) in the management of upper ureteral and renal stones in pediatric patients. Methods We collected data of 112 pediatric patients who were admitted to the xxxx between March 2006 and December 2016 and treated by US-guided MPCNL. Our cohort included upper ureter stones (n = 11), single kidney stones (n = 46), multiple kidney stones (n = 56), and staghorn kidney stones (n = 12). Results Patients were between 0.5 and 13 years old with stone sizes from 10 to 50 mm. Operation duration ranged from 15 to 195 minutes. On average, the nephrostomy tube could be removed after 3.9 days and patients were discharged after 6.5 days. We found that hemoglobin concentration decreased in 34 patients after surgery by 1 to 37.8 g/L. Using US-guided MPCNL, the initial stone-free rate (SFR) was 86.4% and resulted in a final SFR of 95.2%. However, postoperative complications occurred in 18 patients including > 38.5 °C fever in 17 cases and reactive pleural effusion in one case. Blood transfusion was not required in all cases and no sepsis, kidney loss, ureteral stricture, and adjacent organ injury were observed. Follow-up after an average of 8.5 months showed normal renal function without hydronephrosis. However, recurrence of stones > 4 mm was found in 11 patients. Conclusions US-guided MPCNL showed an excellent SFR and low complication rate in the management of pediatric patients with upper ureteral and renal stones.

Comparison of occluder combined with ureteroscopy and microchannel percutaneous nephrolithotomy in the treatment of upper ureteral calculi

Objective To compare the efficacy of occluder combined with ureteroscopic lithotripsy(URL) and minimally invasive percutaneous nephrolithotomy (MPCNL) in the treatment of upper ureteral calculi. Methods Retrospective analysis of 80 patients with upper ureteral calculi from January 2015 to October 2016 in our hospital, including URL in 40 cases of occlusion device (combination group), MPCNL group of 40 cases was performed. The success rate of disposable lithotripsy, stone clearance after 1 month, incidence of surgical complications, and time of surgery and hospitalization were compared between the two surgical groups. Results The success rate of disposable lithotripsy: 87.5%(35/40) in the combined treatment group, 97.5% (39/40) in the MPCNL treatment group, and stone clearance rate after 1 month: the combined treatment group 97.1%(34/35), 97.4%(38/39) of the MPCNL treatment group, the difference was not statistically significant(P>0.05). Surgery and hospital stay: operation time(43.3±13.6)min, hospitalization time(5.2±1.5)d, MPCNL operation time(65.4±14.5)min, hospitalization time(8.4±2.1)d, the difference was statistically significant(P 0.05). Conclusions The ureteral occlusion device combined with ureteroscopy and MPCNL are reliable surgical methods for the treatment of upper ureteral calculi. Key words: Ureteral Calculi; Ureteral occlusion device; Ureteroscopy; Nephrostomy, Percutaneous

Use of a Novel Vacuum-Assisted Access Sheath in Minimally Invasive Percutaneous Nephrolithotomy: A Feasibility Study.

Objective: To assess the safety and efficacy of a novel vacuum-assisted access sheath (VAAS) in minimally invasive percutaneous nephrolithotomy (MPCNL). Materials and Methods: Seventy-five consecutive patients with single renal pelvic stone were treated with MPCNL combined with a novel VAAS. Patients' demographics and surgical outcomes, as well as perioperative and postoperative data, were recorded. Matched-pair analysis in a 1:1 scenario was done in patients who underwent MPCNL by peel-away access sheath (PAAS). All MPCNL was done with a rigid 12F mini-nephroscope and an 18F access sheath. MINDRAY-PM9000 monitor was used to record the renal pelvic pressure (RPP) data. Results: Patients' demographics, stone size, burden, and density (HU) were comparable between the two groups. Operative time was significantly shorter in the study group, at a mean of 32.4 ± 9.6 vs 46.2 ± 11.8 minutes (p < 0.001). The immediate stone-free rate was 89.3% for the VAAS group and 77.3% for the PAAS group (p = 0.049). Patients in the VAAS group had a lower visual analogue pain scale score at postoperative 6 and 24 hours. Mean perioperative RPP was lower in the VAAS group (10.3 ± 4.3 vs 17.8 ± 5.1 mmHg, p < 0.001). More than 50 seconds of accumulative time of high RPP (>30 mmHg) was shown in 13 patients of the VAAS group vs 30 of the PAAS group (p = 0.002). Conclusion: Combining VAAS with high-power holmium laser in MPCNL significantly improves the efficiency of stone retrieval with low RPP. This novel approach also reduces operative time, postoperative fever, and pain due to its simultaneous suction property.

Predictive factors of stone-free rate and complications in patients undergoing minimally invasive percutaneous nephrolithotomy under local infiltration anesthesia.

To evaluate predictive factors affecting the stone-free rates (SFR) and complications of minimally invasive percutaneous nephrolithotomy (MPCNL) under local infiltration anesthesia (LIA) METHODS: A retrospective analysis was conducted on 976 consecutive patients who underwent MPCNL under LIA from January 2015 to June 2018. Postoperative complications were classified according to modified Clavien classification system. Univariate and multivariate logistic regression analyses were used to determine factors affecting SFR and complications. The pain was acceptable with postoperative visual analog scale (VAS) scores being 3.58, 2.99, 2.25, and 2.07 after 0, 6, 24, and 48h, respectively. The SFR after primary MPCNL reached 85.7%. Postoperative complications were recorded in 77 patients (7.9%). In the univariate logistic analysis, larger stone size, staghorn stone, and multiple calyxes were significantly associated with lower SFR. The higher American Society of Anesthesiologists (ASA) score, staghorn stone, positive urine culture, multiple tracts, and longer operation time were associated with occurrence of complications. However, hydronephrosis was associated with lower complication rate. Multivariate analysis indicated that larger stone size (P < 0.001) and staghorn stone (P < 0.001) were associated with lower SFR, while development of complications was independently influenced by higher ASA score (P = 0.002), multiple tract (P = 0.004), and staghorn stone (P = 0.028). MPCNL can be safely and effectively performed under LIA. Stone size and staghorn stone are factors associated with SFR while ASA score, multiple tracts, and staghorn stone are associated with the development of complications. For the first time, we developed a model to predict the SFR and complications in MPCNL under LIA.