Super-mini PCNL (SMP) with suction versus standard PCNL for the management of renal calculi of 1.5 cm-3 cm: a randomized controlled study from a university teaching hospital.

PURPOSE: To assess the safety and efficacy of super-mini PCNL (SMP, 14 Fr) when compared to standard PCNL (sPCNL, 24-30 Fr) in the management of renal calculi of size ranging from 1.5 to 3 cm. METHODS: From February 2021 to January 2022, a total of 100 patients were randomized to either SMP group or sPCNL group in a 1:1 ratio (50 in each group) using computer-generated simple randomization. Demographic data, stone characteristics, operative times, perioperative complications, blood transfusions, postoperative drop in haemoglobin, postoperative pain, duration of hospital stay and stone-free rates were compared between the two groups. RESULTS: Mean stone volume (2.41 cm2 vs 2.61 cm2) and stone-free rates (98% vs 94%, p = 0.14) were similar in both the SMP and sPCNL groups, respectively. The SMP group had significantly longer mean operative times (51.62 ± 10.17 min vs 35.6 ± 6.8 min, p = 0.03). Intraoperative calyceal injury (1/50 vs 7/50, p = 0.42) and mean postoperative drop in haemoglobin (0.8 ± 0.7 g/dl vs 1.2 ± 0.81, p = 0.21) were lower in the SMP group, but not statistically significant. SMP group showed significantly lower mean postoperative pain VAS scores (5.4 ± 0.7 vs 5.9 ± 0.9, p = 0.03) and mean duration of hospital stay (28.38 ± 3.6 h vs 39.84 ± 3.7 h, p = 0.0001). Complications up to Clavien grade 2 were comparable, with grade ≥ 3 complications higher in the standard group, but not statistically significant. CONCLUSION: Super-mini PCNL is equally effective as standard PCNL in treating renal calculi up to 3 cm, with significantly reduced postoperative pain and duration of hospital stay and lower risk of Clavien grade ≥ 3 complications, although with higher operative times.

A proposed mathematical model to help preoperative planning between RIRS and MiniPerc for renal stones between 10 and 20 mm using holmium:Yag laser (Cyber Ho): the stone management according to size-hardness (SMASH) score.

To evaluate the performance of a mathematical model to drive preoperative planning between RIRS and MiniPerc (MP) for the treatment of renal stones between 10 and 20 mm. Patients with a renal stone between 10 and 20 mm were enrolled. A mathematical model named Stone Management According to Size-Hardness (SMASH) score was calculated: hounsfield units (HU) χ stone maximum size (cm)/100. Patients were divided into 4 groups: RIRS with score < 15 (Group A), RIRS with score ≥ 15 (Group B), MP with score < 15 (Group C), MP with score ≥ 15 (Group D). Cyber Ho device was always used. Stone free rate (SFR) was assessed after 3 months. Complication rate and need for auxiliary procedures were evaluated. Between January 2019 and December 2021, 350 patients were enrolled (87, 88, 82 and 93 in Groups A, B, C and D). Mean stone size was 13.1 vs 13.3 mm in Group A vs B (p = 0.18) and 16.2 vs 18.1 mm in Group C vs D (p = 0.12). SFR was 82%, 61%, 75% and 85% for Groups A, B, C and D. SFR was comparable between Groups C and D (p = 0.32) and Groups A and C (p = 0.22). SFR was significantly higher in Group A over B (p = 0.03) and in Group D over B (p = 0.02). Complication rate was 2.2%, 3.4%, 12.1%, 12.9% for Groups A, B, C, D. RIRS and MP are both safe and effective. The mathematical model with the proposed cut-off allowed a proper allocation of patients between endoscopic and percutaneous approaches.Registration number of the study ISRCTN55546280.

Percutaneous Nephrostomy as a Procedure in the Treatment of Urinary Tract Obstruction - Experiences in the University Clinic of Urology in Skopje.

INTRODUCTION: Obstructive uropathy encompasses various urinary tract obstructions, leading to changes in urine flow, kidney pressure, and impaired kidney function. Predicting renal recovery from obstructive uropathy, can be challenging and necessitates treatment, as in percutaneous nephrostomy (PNS) drainage. The choice of drainage method depends on patient-specific factors and local expertise. According to the data for the Republic of North Macedonia, in the register of the European Renal Association, in the last few years, there has been an increase in the percentage of patients with obstructive nephropathy from 7.6% to 8.9% who end up on a chronic hemodialysis program. Prompt relief from urinary tract obstruction is essential to preserve renal function and prevent complications. The aim of this study is to present our initial data analysis of recent experience in the use of nephrostomies as a method for temporary or long-term resolution of obstructive nephropathy, in terms of safety and success in preserving kidney function and reducing the number of patients on hemodialysis. MATERIALS AND METHODS: This study analyzed the medical records of 24 patients with obstructive uropathy who underwent PNS placement. Data were collected for the type and degree of obstruction from the ultrasonographic examination. A pig tail nephrostomy was used, with a dilator, guided under ultrasound and controlled with contrast and fluoroscope. Obstructive nephropathy was defined as an elevation of the serum creatinine > 109 µmol/L, before the intervention. Glomerular filtration rate (GFR) was calculated according to the formula CKD epi in ml/min. Each placement of the PNS was considered as an individual procedure and the data of 38 placed nephrostomies were analyzed. We compared the laboratory analyses from the day before (D0) PNS placement and on the seventh day (D7) after PNS placement. The reduction of values for red blood cells (RBC) and hemoglobin (Hb) baseline values from D0 to D7 and the need for transfusion after the procedure were defined as a complication-bleeding. The increase in total counts of the white blood cells (WBC) and C-reactive protein (CRP) from the baseline values from D0 to D7 were defined as a complication-infection. Standard statistical methods were used for data processing. RESULTS: Most patients, 17 (70%), had malignant disease as the cause of obstruction. Unilateral obstruction was more common, detected in 24 (63%) of procedures, with a high degree of hydronephrosis. Obstructive nephropathy, marked by elevated serum creatinine, was observed in 23 (60%) cases before PNS placement. Complications included bleeding and infection but did not result in any fatalities. When comparing the laboratory analysis before PNS placement (D0) and seven days later (D7), a statistically significant decrease in serum creatinine (225±161 vs. 162±145, p=0.005) and an increase in GFR (47±39 vs.59±34, p= 0.005) were observed. CONCLUSION: Percutaneous nephrostomy is a safe and effective treatment option for urinary tract obstruction, especially in patients with malignancies. Continuous monitoring is essential to assess long-term complications and the longevity of PNS functionality. This procedure offers a significant benefit in preserving renal function and minimizing the need for hemodialysis in these patients.

Bilateral Single-session PCNL with Minimally Invasive Technique in Pediatric Nephrolithiasis.

PURPOSE: To assess outcomes of bilateral single-session percutaneous nephrolithotomy (PCNL) with minimally invasive techniques in pediatric population. MATERIALS AND METHODS: From August 2015 to July 2021, 45 children (including 12 infants) were treated with bilateral single-session PCNL, which included miniPCNL (12-16-Fr) and Microperc (4.8-Fr). Patient, stone and operation-related characteristics, stone-free rate (SFR) and complication rate (CR) were compared using ANOVA. Independent predictors were determined using multivariate linear regression. RESULTS: The mean stone burden was 3.2 cm in sum diameter for both kidneys. For bilateral kidneys, the mean operative time was 61.6min and SFR was 93.3%; CR was 53.3%, of which complications of Clavien grade 1 and 2 accounted for 46.7%. Bilateral Microperc, bilateral miniPCNL and Microperc plus miniPCNL was performed in 19, 14 and 12 children respectively. Both irrigation volume and postoperative stay were less in groups with Microperc. Both SFRs and CRs were satisfactory for the three groups. Self-limiting hematuria represented the most common complication of all cases (33.3%), especially in groups with miniPCNL. The stone burden was the only independent predictor for operative time (P < .001) and the postoperative complication (P = .008). Children with older age (P = .009), higher body mass index (P = .016) or a higher stone burden (P < .001) received larger irrigated fluid volume. Microperc was associated with less irrigated fluid volume (P = .001). Children with Clavien grade 3 complications (P = .004) spent prolonged postoperative hospital stay. CONCLUSION: With favourable SFR and acceptable CR, bilateral single-session PCNL with minimally invasive techniques might be an effective and safe procedure for pediatric nephrolithiasis.

Risk factors of high fluid absorption in patients treated with mini-PCNL: a single-center prospective study.

BACKGROUND: The factors influencing fluid absorption in mini-percutaneous nephrolithotripsy (mini-PCNL) are still unknown. We aim to investigate the factors that influence irrigation fluid absorption during mini-PCNL. METHODS: A total of 94 patients who underwent mini-PCNL were included in this prospective study. The endoscopic surgical monitoring system (ESMS) was used to measure the volume of irrigation fluid absorbed during the procedure. Irrigating time, the total volume of irrigation fluid, stone size, S.T.O.N.E. score, hemoglobin, electrolyte levels, and postoperative complications were recorded. RESULTS: A significant correlation was observed between fluid absorption and the presence of postoperative fever, and based on this phenomenon, patients were divided into low and high fluid absorption groups. The serum creatinine level in the high fluid absorption group was significantly high (7 vs. 16.5, p = 0.02). Significant differences were observed between the low and high fluid absorption groups in terms of mean stone size (21.70 mm vs. 26.78 mm), presence of stone burden ≥ 800 mm2 (4% vs. 23%), S.T.O.N.E. score > 8 (4% vs. 38%), the fluid used > 18,596 ml (19% vs. 78%), irrigation time (55.61 min vs. 91.28 min), and perfusion rate (24% vs. 45%) (all p < 0.05). The rates of postoperative fever and SIRS in the high fluid absorption group were significantly high (p < 0.05). CONCLUSIONS: Mean stone size, presence of stone burden ≥ 800 mm2, S.T.O.N.E. score > 8, the fluid used > 18596 mL, irrigation time, and perfusion rate are risk factors of intraoperative fluid absorption in mini-PCNL.

PCNL vs. two staged RIRS for kidney stones greater than 20 mm: systematic review, meta-analysis, and trial sequential analysis.

INTRODUCTION: Percutaneous nephrolithotomy (PCNL) is considered the gold standard treatment for kidney stones greater than 20 mm. However, retrograde intrarenal surgery (RIRS) may achieve the same stone-free rate with repeated procedures, and potentially fewer complications. This study aimed to compare the efficacy and safety of PCNL and two-staged RIRS. EVIDENCE ACQUISITION: We conducted a systematic search in PubMed, Embase, Scopus, Cochrane, and Web of Science for studies comparing PCNL and RIRS for kidney stones greater than 20mm. The primary outcome is stone-free rate (SFR) of PCNL and RIRS (repeated once if needed). Secondary outcomes were SFR of PCNL versus RIRS (single procedure), operative time, hospital stay, need for auxiliary procedures, and complications. We performed a subgroup analysis for randomized trials, non-randomized trials, and patients with solitary kidney. We performed a trial sequential analysis for the main outcome. EVIDENCE SYNTHESIS: We included 31 articles, with 1987 patients in the PCNL and 1724 patients in RIRS. We confirmed the traditional result that after a single procedure PCNL has a higher SFR. We also found that comparing the SFR of PCNL and RIRS, repeated up to two times if needed, no difference in SFR was observed. Surprisingly, only 26% (CI95 23%-28%) of the patients required a second RIRS. In the trial sequential analysis, the last point of the z-curve was within futility borders. We observed that PCNL has a higher incidence of complications (RR=1.51; CI95 1.24, 1.83; P<0.0001; I2=28%), specifically CD2 (RR=1.82; CI95 1.30, 2.54; P=0.0004; I2=26%) and longer hospital stay (MD 2.57; 2.18, 2.96; P<0.00001; I2-98%). No difference was observed regarding operative time. CONCLUSIONS: RIRS repeated up to two times is equivalent to PCNL in terms of the SFR and may have the same safety.

Learning curve of ultrasound-guided percutaneous nephrolithotripsy in the treatment of complex renal calculi.

OBJECTIVE: This study was performed to investigate the learning curve of ultrasound-guided percutaneous nephrolithotripsy (PCNL) for the treatment of complex renal calculi. METHODS: Seventy-two patients with complex renal stones who underwent ultrasound-guided PCNL by the same operator from November 2016 to September 2020 were retrospectively analyzed. The learning curve of PCNL for complex renal stones was analyzed using multifactorial cumulative sum (CUSUM) analysis and best-fit curves. RESULTS: The CUSUM best-fit curve peaked at Case 36, which represented the minimum number of cumulative cases required to cross the learning curve for this surgical procedure. Accordingly, the learning curve was divided into a learning improvement period (36 cases) and a proficiency phase (36 cases). Compared with the learning improvement period, the proficiency phase was characterized by a shorter puncture time and operation time, a smaller drop in the hemoglobin level, and a lower postoperative complication rate. CONCLUSION: The learning curve of PCNL for the treatment of complex renal calculi can be divided into a learning improvement period and a proficiency phase, and the minimum cumulative number of cases is 36.

Transient ureteral obstruction after mini-percutaneous nephrolithotomy is associated with stone volume and location: results from a single-center, real-life study.

PURPOSE: To evaluate the rate of and predictors of ureteral obstruction after mini-percutaneous nephrolithotomy (mPCNL) for kidney stones. METHODS: We analyzed data from 263 consecutive patients who underwent mPCNL at a single tertiary referral academic between 01/2016 and 11/2022. Patient's demographics, stone characteristics, and operative data were collected. A nephrostomy tube was placed as the only exit strategy in each procedure. On postoperative day 2, an antegrade pyelography was performed to assess ureteral canalization. The nephrostomy tube was removed if ureteral canalization was successful. Descriptive statistics and logistic regression models were used to identify factors associated with a lack of ureteral canalization. RESULTS: Overall, median (IQR) age and stone volume were 56 (47-65) years and 1.7 (0.8-4.2) cm3, respectively. Of 263, 55 (20.9%) patients showed ureteral obstruction during pyelography. Patients without ureteral canalization had larger stone volume (p < 0.001), longer operative time (p < 0.01), and higher rate of stones in the renal pelvis (p < 0.01) than those with normal pyelography. Length of stay was longer (p < 0.01), and postoperative complications (p = 0.03) were more frequent in patients without ureteral canalization. Multivariable logistic regression analysis revealed that stone volume (OR 1.1, p = 0.02) and stone located in the renal pelvis (OR 2.2, p = 0.04) were independent predictors of transient ureteral obstruction, after accounting for operative time. CONCLUSION: One out of five patients showed transient ureteral obstruction after mPCNL. Patients with a higher stone burden and with stones in the renal pelvis are at higher risk of inadequate ureteral canalization. Internal drainage might be considered in these cases to avoid potential complications.

What should the optimal access site be for percutaneous treatment of anterior lower pole calyx stones?

OBJECTIVES: Compared to other stone groups, anterior calyx stones are more challenging for endourologists to treat. This study aims to evaluate the differences between our latest technique and conventional techniques for treating anterior calyx stones in the lower pole. MATERIALS AND METHODS: Patients with isolated anterior lower pole calyx or complex lower pole stones with anterior calyx branching were included in the study. The first group included lower pole access, while the second group included percutaneous treatment through the middle or upper pole. In the first group, the posterior calyx or direct anterior calyx approach was utilised depending on whether the stone was isolated calyx, complex structure or calyx anatomy, while in the second group, percutaneous nephrolithotomy was performed through the middle or upper pole posterior calyx access. RESULTS: There were 37 patients in Group 1 and 25 patients in Group 2. Both groups were similar regarding patient age, sex, stone burden, and stone localisation (p > 0.05). When comparing operative and post-operative data between groups, it was found that the stone clearance rate, number of accesses, and haematocrit decrease were statistically superior in the second group (p: 0.003, p: 0.002, p: 0.018), with no significant difference in mean operative time, length of hospital stay, fluoroscopy time and pain score (p > 0.05). CONCLUSIONS: Percutaneous surgery utilising an access from a calyx distal to the stone may offer better clearance and lower morbidity rates for lower pole stones involving the anterior calyx.

Antegrade flexible ureteroscopy-assisted percutaneous nephrolithotomy for staghorn calculi: a prospective randomized controlled study.

The aim is to compare the efficacy and safety between single percutaneous nephrolithotomy (sPNL) and antegrade flexible ureteroscopy-assisted percutaneous nephrolithotomy (aPNL) for the treatment of staghorn calculi. A prospective randomized controlled study was conducted at the Second Hospital of Tianjin Medical University. A total of 160 eligible patients were included, with 81 in the sPNL group and 79 in the aPNL group. The study first compared the overall differences between sPNL and aPNL. Then, the patients were divided into two subgroups: Group 1 (with less than 5 stone branches) and Group 2 (with 5 or more stone branches), and the differences between the two subgroups were further analyzed. The results showed that aPNL had a higher stone-free rate (SFR) and required fewer percutaneous tracts, with a shorter operation time compared to sPNL (P < 0.05). Moreover, aPNL significantly reduced the need for staged surgery, particularly in patients with 5 or more stone branches. Moreover, there were no significant differences in the changes of hemoglobin levels and the need for blood transfusions between the sPNL and aPNL groups, and the incidence of multiple tracts was lower in the aPNL group. The two groups showed comparable rates of perioperative complications. We concluded that aPNL resulted in a higher SFR for staghorn calculi, and required fewer multiple percutaneous tracts, reduced the need for staged surgery, and had a shorter operative time than PNL alone, especially for patients with 5 or more stone branches. Furthermore, aPNL did not increase the incidence of surgical complications.

Ureteral stent after PCNL: is leaving the threads through the percutaneous tract safe and better tolerated?

OBJECTIVE: To assess safety, urinary symptoms, and feasibility of JJ stent removal with exteriorized threads through the percutaneous tract after percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: Prospective, transversal, comparative, experimental, randomized 1-to-1 cohort study in 52 patients who underwent "tubeless" PCNL from October 2020 to November 2022. Group A with threads through the urethra and Group B through the percutaneous tract. The validated USSQ (Ureteral Stent Symptom Questionnaire) was applied in the Urology office a week after the procedure, and the JJ stent was withdrawn by pulling the threads. Hemoglobin and urine culture, and pre- and post-surgery were evaluated. RESULTS: There is a statistically significant difference in favor of group B when comparing urinary symptoms (p = 0.008), body pain (p = 0.009), and general condition (p = 0.042), mainly for non-urgency incontinence, frequency of analgesic use, and dysuria. There were significant differences between groups (p = 0.028, p = 0.026, p = 0.027, respectively). There is no association with urinary infections (p = 0.603) nor an increased risk of bleeding (p = 0.321). CONCLUSION: The removal of the JJ stent with exteriorized threads through the percutaneous tract after PCNL in the office is a feasible and safe procedure if it is removed before 8 days and has better tolerance regarding the urinary symptoms.

Complications Subsequent to Urinary Tract Stent Placement: An Overview Focusing on the Imaging of Cancer Patients.

Ureteral involvement by a tumor is common, and both partial and complete obstructions can result in symptoms that are distressing and debilitating, especially in cancer patients for whom the resection of the primary tumor is not considered an option. Maintaining ureteric patency in these patients is a challenge. In addition, in cases where a patient has undergone nephroureterectomy due to primary transitional cell cancer, it becomes necessary to decompress the urinary tract to preserve the contralateral kidney from irreversible damage. This is possibly due to ureteral stenting, both retrograde and anterograde, and percutaneous nephrostomy (PCN). Since imaging plays an important role in the routine monitoring of stents, their more and more increasing use requires radiologists to be familiar with these devices, their correct position, their potential complications, and their consequences. The aim of this review is to offer a comprehensive review of the imaging features of some urinary stents and to show the complications encountered in cancer patients as a direct consequence of an invasive diagnostic or therapeutic procedure. Specifically, we focus on ureteral stents and PCN.

Comparing Balloon Dilation to Non-Balloon Dilation for Access in Ultrasound-Guided Percutaneous Nephrolithotomy: A Systematic Review and Meta-Analysis.

PURPOSE: This study aims to evaluate the safety and efficacy of ultrasound-guided balloon dilation compared to non-balloon dilation for percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: A systematic review and meta-analysis were conducted by searching PubMed, EMBASE, and the Cochrane Library. Results were filtered using predefined inclusion and exclusion criteria as described and meta-analysis was performed using Review Manager 5.4 software. RESULTS: A total of six studies involving 1189 patients who underwent PCNL were included. The meta-analysis results demonstrated that compared to non-balloon dilation, balloon dilation was associated with reduced haemoglobin drop [mean difference (MD) = -0.26, 95% CI = -0.40 ~ -0.12, P = 0.0002], decreased transfusion rate [odds ratio (OR) = 0.47, 95% CI = 0.24 ~ 0.92, P = 0.03], shorter tract establishment time (MD = -1.30, 95% CI = -1.87 ~ -0.72, P < 0.0001) and shorter operation time (MD = -5.23, 95% CI = -10.19 ~ -0.27, P = 0.04). CONCLUSIONS: Overall, ultrasound-guided balloon dilatation offered several advantages in PCNL procedures. It facilitated faster access establishment, as evidenced by shorter access creation time. Additionally, it reduced the risk of kidney injury by minimizing postoperative haemoglobin drop and decreasing the need for transfusions. Moreover, it enhanced the efficiency of surgery by reducing the operation time. However, it is important to note that the quality of some included studies was subpar, as they did not adequately control for confounding factors that may affect the outcomes. Therefore, further research is necessary to validate and strengthen these findings.

Percutaneous nephrolithotomy guided by 5G-powered robot-assisted teleultrasound diagnosis system: first clinical experience with a novel tele-assistance approach (IDEAL stage 1).

BACKGROUND: To demonstrate the technical feasibility of percutaneous nephrolithotomy (PCNL) guided by 5G-powered robot-assisted teleultrasound diagnosis system (RTDS) in a complex kidney-stone (CKS) cohort and present our preliminary outcomes. PCNL is highly skill-required, which hinders it popularization in primary medical units of remote regions. We designed an innovative tele-assistance approach to make PCNL easy to be operated by inexperienced surgeons. METHODS: This was a prospective proof-of-concept study (IDEAL phase 1) on intraoperative tele-assistance provided by online urological experts via a 5G-powered RTDS. Total 15 CKS patients accepted this technology. Online experts manipulated a simulated probe to assist unskilled local operators by driving a patient-side robot-probe to guide and monitor the steps of access establishment and finding residual stones. RESULTS: Median total delay was 177ms despite one-way network-connecting distance > 5,800 km. No perceptible delay of audio-visual communication, driving robot-arm or dynamic ultrasound images was fed back. Successful tele-assistance was obtained in all cases. The first-puncture access-success rate was 78.6% with a one-session SF rate of 71.3% and without complications of grade III-V. CONCLUSIONS: The current technology based on 5G-powered RTDS can provide high-quality intraoperative tele-assistance, which has preliminarily shown satisfactory outcomes and reliable safety. It will break down a personal competence-based barrier to endow PCNL with more popular utilization. TRIAL REGISTRATION: The study was approved by ethics committee of the Xinjiang Kezhou People's Hospital and ethics committee of the First Affiliated Hospital of Nanjing Medical University and was registered on http://www.chictr.org.cn (ChiCTR2200065849, 16/11/2022).

Percutaneous nephrolithotomy non-papillary puncture trends. A review of the literature.

Percutaneous nephrolithotomy (PCNL) is the gold standard of treatment for large renal calculi. Papillary puncture is the mainstay of treatment for large renal calculi, but the non-papillary has been introduced and gained some interest. The aim of this study is the investigation of trends of non-papillary access for PCNL over the years. A review of the literature took place and 13 publications were included in the study. Two experimental studies investigating the feasibility of non-papillary access were found. Five cohort prospective and 2 retrospective studies for non-papillary access and 4 comparative studies between papillary and non-papillary access were included. Non papillary access is a technique that has been proved as a safe and efficient solution that keeps up with the latest endoscopic trends. A wider use of this method could be expected in the future.

Impact of Renal Access Angle and Speed of Nephroscope Retrieval Movements on the Vortex Effect.

OBJECTIVE: To analyze the influence of different renal access angles (AAs) and nephroscope retrieval speeds on the efficacy of the vortex effect (VE) in mini-percutaneous nephrolithotomy (mini-PCNL). This study aimed to understand the poorly understood physical components of the VE. MATERIALS AND METHODS: A Pexiglas™ (KUS®) model was built based on the dimensions of a 15/16 F mini-PCNL set (Karl Storz). The flow rate was continuous via an automatic pump and calibrated to achieve hydrodynamic equivalence to the real equipment. One experiment consisted of manually retrieving all 30 stone phantoms (3 mm diameter) utilizing only the VE. Cumulative time to retrieve all stones was measured. An accelerometer recorded instant speeds of the nephroscope every 0.08 seconds (s), and 3 experiments were performed at each angle (0°, 45°, and 90°). A logistic regression model was built utilizing maximum speeds and access angles to predict the effectiveness of the VE. RESULTS: Mean cumulative time for complete stone retrieval was 28.1 seconds at 0° vs 116.5 seconds at 45° vs 101.4 seconds at 90° (P < .01). We noted significantly higher speeds at 0° compared to 45° and 90° (P < .01); however, differences in average and maximum speed between 45° and 90° were not statistically significant (P = .21 and P = .25, respectively). The regression model demonstrated a negative association between increasing maximum speed and VE's effectiveness (OR 0.547, CI 95% 0.350-0.855, P < .01). When controlling for maximum speed, the 0° angle had significantly higher chances of achieving at least a partially effective VE. CONCLUSION: Increasing the renal access angle or nephroscope extraction speed negatively impacts the effectiveness of the VE. This significantly increased procedure time in the laboratory model, suggesting that the VE is less effective at higher sheath angles.

Vacuum-assisted Mini-percutaneous Nephrolithotomy for 2-3-cm Renal Stones: A Comparative Study with Retrograde Intra-renal Surgery.

PURPOSE: To compare vacuum-assisted percutaneous nephrolithotomy (VAmini-PCNL) with retrograde intra-renal surgery (RIRS) for the treatment of renal stones measuring 2-3 cm in diameter. MATERIAL AND METHODS: This retrospective study included children receiving treatment for pyelocalyceal stones of 2-3 cm in diameter from November 2018 to September 2022. Consecutive patients undergoing VAmini-PCNL after 2020 were compared with a historically matched group undergoing RIRS. VAmini-PCNL was performed using a 12-Ch nephroscope through a 16-Ch vacuum ClearPetra access sheet. RIRS was performed using a flexible ureteroscope through a ureteral sheath. The endpoints included the need for pre-stenting, duration of surgery, complications, stone-free rate (SFR), and need for secondary procedures. RESULTS: The patients were grouped into two with 15 patients for each group. VAmini-PCNL group was not different from the RIRS one for age at surgery [median (range) 6.6 (1-12)years vs. 7.7 (1.5-14)years], and stone diameter [median (range) 2.4 (2.0-2.9)cm vs. 2.3 (2.1-2.8)cm] and density [median (range) 577.5 (421-1068) vs. 541.5 (462-927) Hunsfield Units]. Pre-stenting was necessary in five RIRS patients (33 %). The median duration of surgery was 85.3 (76-112)min for VAmini-PCNL vs. 150.6 (132-167)min for RIRS, p = 0.00001. No major complications were observed. The SFR was 100 % after VAmini-PCNL and 60 % after RIRS, p = 0.02. All residual fragments were removed with a second RIRS. CONCLUSION: VAmini-PCNL was feasible and safe in children aged >1 year. It allowed for a significantly higher SFR despite a significantly shorter operative time than RIRS, which also requires pre-stenting in one-third of patients and a second RIRS in 40 % of cases. LEVEL OF EVIDENCE: III.

Comparison of Two Centers' Experience in Pediatric Supine and Prone Miniaturized Percutaneous Nephrolithotomy with Propensity Match Analysis.

Introduction: Percutaneous nephrolithotomy (PNL) is the treatment of choice in children with complex and large stones. With the experience gained from adult practice, supine PNL is increasingly performed in children as well. We aimed to evaluate the comparative results of prone and supine mini-PNL (m-PNL) performed for large/complex stones in children. Patients and Methods: The study included children who underwent supine and prone m-PNL at two centers between September 2019 and 2022. Patients were divided into two groups with a 1:1 ratio to index supine m-PNL and prone m-PNL cases for the size, number, location of the stones, degree of hydronephrosis, and age. Operative related parameters, success, and complication rates are being discussed on a procedure-based manner. Results: Forty-two patients (21 supine and 21 prone) were included. The mean age was 9.6 ± 4 years and mean stone size was 28.8 ± 13.6 mm. Regarding the operative data, the mean duration of procedure time was 65.7 ± 17.8 minutes in supine group, whereas 86.9 ± 19.0 minutes in prone group (p = 0.001). Fluoroscopy time was shorter in supine group (p = 0.027). Tubeless PNL was performed in 11 cases of prone group (52%), whereas this number was 18 (86.7%) in supine group (p = 0.019). Stone-free rates were similar in both groups (supine m-PNL: 90.5%, prone m-PNL: 85.7%, p = 0.634). Complications were minor in nature in most of the cases of both groups, which resolved with supportive measures in a short period of time. However, there was a statistically significant difference regarding the location and number accesses between two groups (p = 0.008). Simultaneous flexible ureterorenoscopy was performed in eight patients in the supine PNL group (<0.001). Conclusions: Our current findings and the highly limited data reported in the literature indicate that as an established minimal invasive treatment alternative m-PNL procedure in supine position can also be performed with similar success and complication rates in pediatric population.

Gel Rolls Increase Percutaneous Nephrolithotomy Radiation Exposure.

Introduction: Despite increasing interest in reducing radiation doses during endoscopic stone surgery, there is conflicting evidence as to whether percutaneous nephrolithotomy (PCNL) positioning (prone or supine) impacts radiation. We observed clinically that a patient placed prone on gel rolls had higher than expected radiation with intraoperative CT imaging and that gel rolls were visible on the coaxial imaging. We hypothesized that gel rolls directly increase radiation doses. Methods: Anthropomorphic experiments to simulate PCNL positions were performed using a robotic multiplanar fluoroscopy system (Artis Zeego Care+Clear, Siemens) and a 5-second coaxial imaging protocol (5s BODY). A fluoroscopy phantom was placed in various positions, including prone on a gel roll; prone on blankets of equal thickness; prone and supine directly on the table; and modified supine (MS) positions using a thin gel roll or rolled blanket. Impacts of C-arm direction and use of a 1 L saline bag were also evaluated. Measured dose area product (DAP) was compared for the groups. Results: Measured DAP was found to increase by 146 µGy*m2 (287%) when prone on gel rolls compared with only 62.29 (23%) when placed on blankets of equal thickness, although the model likely both overstates the relative impact and understates the absolute impact that would be seen clinically. Measured DAP between experimental groups also varied considerably despite fluoroscopy time being held constant. Conclusions: Our experiments support our hypothesis that gel rolls directly increase radiation dose, which has not been previously reported, using an anthropomorphic model. Surgeons should consider radiolucent materials for positioning to limit radiation exposure to patients and the surgical team.

Single Specialty-Operated Renal Stone Removal: Initial Experience from 3 Interventional Radiology Centers.

This retrospective analysis of the feasibility and safety of percutaneous renal stone removal using single-use flexible ureteroscopes was conducted at 3 academic centers. Twelve patients (58% men) underwent 14 percutaneous renal stone removal procedures between December 2021 and March 2023. All patients experienced symptom improvement and resolution of obstruction after stone removal. The procedural success rate was 92%. Only 1 patient required an additional stone removal procedure. No major adverse events occurred during or after the procedures. The percutaneous nephrostomy removal rate was 92%, with a median tube removal time of 5 weeks. The median procedural and pulsed fluoroscopy times were 106.5 and 16.3 minutes, respectively. Preliminary findings demonstrated that percutaneous renal stone removal using single-use endoscopes by interventional radiologists is feasible and safe.