An unusual case of an 0.018-inch (0.457 mm) guidewire fracture during primary percutaneous nephrostomy for percutaneous nephrolithotomy treated without removal and followed up for 5 years: A case report and literature review.

INTRODUCTION: Although rare, guidewire fractures can occur during interventional procedures. In most cases, the fractured guidewire segment can be removed. PATIENT CONCERNS: We report the case of a 54-year-old woman who experienced a guidewire fracture during percutaneous nephrostomy (PCN) for percutaneous nephrolithotomy to remove renal stones. DIAGNOSIS: Nephrolithiasis. INTERVENTIONS: PCN and percutaneous nephrolithotomy. OUTCOMES: In this case, the remaining segment could not be removed and caused inflammation and infection. However, her symptoms improved with inpatient treatment. Therefore, she was discharged from the hospital and followed up for 5 years. CONCLUSION: When performing PCN to remove renal stones, the possibility of a guidewire fracture must be considered. If resistance or scraping is felt while handling the guidewire, then it should be replaced.

Initial Clinical Experience With a Novel Robotically Assisted Platform for Combined Mini-Percutaneous Nephrolithotomy and Flexible Ureteroscopic Lithotripsy.

PURPOSE: We sought to evaluate the technical feasibility of performing a combined robotically assisted mini-percutaneous nephrolithotomy (PCNL) and flexible ureteroscopy (URS) procedure by a single urologist using the MONARCH Platform, Urology (Johnson & Johnson MedTech, Redwood City, California). MATERIAL AND METHODS: In this prospective, first-in-human clinical trial, 13 patients underwent robotically-assisted PCNL for renal calculi at the University of California-Irvine, Department of Urology. Successful completion of the procedure was assessed as the primary endpoint. Postoperative adverse events were monitored for 30 days following the completion of the procedure. Stone ablation efficiency was evaluated on postoperative day 30 with low-dose 2-3 mm slice CT scans. Patients were classified according to the maximum length of their residual stone fragments as either absolute stone-free (Grade A), < 2 mm remnants (Grade B), or 2.1-4.0 mm remnants (Grade C). RESULTS: The combined robotic mini-PCNL and URS procedure was successfully completed in 12 of 13 procedures. No robotic device-related adverse events occurred. Preoperative stone burden was quantified by both maximum linear measurement (median 32.8 mm) as well as by CT-based volume (median 1645.9 mm3). Using the unique robotically assisted targeting system, percutaneous access was gained directly through the center of the renal papilla in a single pass in all cases. Median operative time was 187 minutes (range: 83-383 minutes). On postoperative day 30, a 98.7% (range: 72.9%-100.0%) volume reduction was achieved, with 5 Grade A (38.5%), 1 Grade B (7.7%), and 2 Grade C (15.4%). Three patients experienced complications (2 grade 1 and one grade 2 Clavien-Dindo). CONCLUSIONS: Our preliminary investigation demonstrates the safety, efficacy, and feasibility of a unique robotic-assisted combined mini-PCNL and URS platform.

Evaluating the safety of bipolar nephrostomy tract cauterization "BNTC" towards a safe tubeless percutaneous nephrolithotomy: a randomized controlled trial.

To assess the safety and effectiveness of tubed versus tubeless percutaneous nephrolithotomy (PCNL) after tract inspection and bipolar cauterization of the significant bleeders. Patients who were scheduled for PCNL were screened for enrollment in this prospective randomized controlled trial. The patients were randomly assigned to one of two groups; Group 1 received tubeless PCNL with endoscopic inspection of the access tract using bipolar cauterization of the significant bleeders only, while Group 2 had a nephrostomy tube was inserted without tract inspection. We excluded patients with multiple tracts, stone clearance failure, and significant collecting system perforation. We recorded blood loss, hemoglobin drop after 6 h, postoperative analgesia requirements, hospital stay, and the need for angioembolization. A total of 110 patients completed the study. There were no significant differences between the two groups in in terms of demographic characteristics. Likewise, there was no significant difference in the mean decrease in hemoglobin after 6 h and the frequency of blood transfusion. However, the incidence of hematuria within the first 6 h (p = 0.008), postoperative pain scale (p = 0.0001), the rate of analgesia requirement (p = 0.0001) and prolonged hospital stay (p = 0.0001) were significantly higher in Group 2. Only 9 cases of tract screened patients (16% of group 1) required cauterization. Tubeless PCNL with tract inspection and cauterization of bleeders can provide a safer tubeless PCNL with less postoperative pain, analgesia requirement, and same-day discharge.

Development of a novel percutaneous digital flexible nephroscope: its use and application.

BACKGROUND: Renal calculi are one of the most frequent diseases in urology, and percutaneous nephrolithotomy (PCNL) being the gold standard for treating renal calculi larger than 2 cm. However, traditional rigid nephroscope cannot bend, presents significant limitations during PCNL. This study aims to develop a novel digital flexible nephroscope for PCNL and verify its safety and efficacy using 3D printed models and ex vivo porcine kidney models, providing new equipment for PCNL. METHODS: Based on the determined technical parameters, the novel digital flexible nephroscope was manufactured. First, 3D-printed model and ex vivo porcine kidney models were utilized to simulate the PCNL procedures. Then, the traditional rigid nephroscope and the novel digital flexible nephroscope were utilized to simulate the PCNL procedures on 10 ex vivo porcine kidneys for comparison. We observed and recorded the renal calyces visualized and accessed by both the traditional rigid nephroscope and the novel digital flexible nephroscope. RESULTS: In both the 3D printing and ex vivo porcine kidney models, the novel percutaneous digital flexible nephroscope smoothly entered the renal collecting system through the percutaneous renal tract. It freely changed angles to reach most target calyces, demonstrating significant advantages over the traditional rigid nephroscope. CONCLUSION: The successful development of the novel percutaneous digital flexible nephroscope allows it to be used either independently or as an adjunct in complex stone cases, providing more effective and safer surgical equipment for percutaneous nephrolithotomy.

Ultrasound-guided renal puncture followed by endoscopically guided tract dilatation vs standard fluoroscopy-guided percutaneous nephrolithotomy for non-opaque renal stones; a randomized clinical trial.

This study was designed to evaluate the non-inferiority of ultrasound puncture followed by endoscopically guided tract dilatation compared to the standard fluoroscopy-guided PCNL. Forty patients with non-opaque kidney stones eligible for PCNL were randomly divided into two groups. The standard fluoroscopy-guided PCNL using the Amplatz dilator was performed in the XRAY group. In the SONO group, the Kidney was punctured under an ultrasound guide followed by tract dilatation using a combination of the Amplatz dilator based on the tract length and an endoscopically guided tract dilatation using a bi-prong forceps in cases of short-advancement. The primary outcome was successful access. In 90% of cases in the XRAY and 95% in the SONO group access dilatation process was performed uneventfully at the first attempt (p = 0.5). In 45% of cases in the SONO group, bi-prong forceps were used as salvage for short-advancement. In one case in the X-ray group over-advancement occurred. One month after surgery, the stone-free rate on the CT-scan was 75% for the X-ray group and 85% for the SONO group (p = 0.4). There were no significant differences in operation time, hospitalization duration, transfusion, or complication rates between the two groups. We conclude that ultrasound-guided renal puncture, followed by endoscopically guided tract dilatation can achieve a high success rate similar to X-ray-guided PCNL while avoiding the harmful effects of radiation exposure and the risk of over-advancement.

Holmium:yttrium-aluminium-garnet laser with MOSES technology is more efficient than thulium fibre laser in supine mini-percutaneous nephrolithotomy.

OBJECTIVES: To address the paucity of literature comparing outcomes achieved with utilisation of the high-power holmium:yttrium-aluminium-garnet (Ho:YAG) laser with MOSES technology vs those achieved with the thulium fibre laser (TFL) in mini-percutaneous nephrolithotomy (PCNL). METHODS: A retrospective review was performed of patients undergoing supine mini-PCNL between August 2021 and May 2023. Exclusion criteria were urinary diversion, simultaneous utilisation of >1 laser platform, use of any other form of fragmentation, and ureteric stones. The Ho:YAG platform (Lumenis Pulse P120H™ with MOSES technology, 120W; Boston Scientific®) and the TFL (Soltive SuperPulsed Thulium Fibre [SPTF], 60W; Olympus®) were compared. Data on stone-free rate (SFR) were determined by computed tomography performed on the first postoperative day and presented as absence of stone fragments, no fragments larger than 2 mm, or no fragments larger than 4 mm. RESULTS: A total of 100 patients met the inclusion criteria, 51 mini-PCNLs with the Ho:YAG laser and 49 with the SPTF laser. No significant differences in demographics or stone characteristics were detected between the two groups. The Ho:YAG laser utilised less energy and time, resulting in higher ablation efficiency (P < 0.05) and less total operating time (P < 0.05). Overall, there was no difference in SFR in any category between the Ho:YAG group and the SPTF group (no fragments: relative risk [RR] 0.81, 95% confidence interval [CI] 0.59-1.12, P = 0.21; fragments <2 mm: RR 0.86, 95% CI 0.67-1.10, P = 0.23; fragments <4 mm: RR 0.96, 95% CI 0.80-1.15, P = 0.67). CONCLUSIONS: Although we observed an equivalent postoperative SFR, this study supports a shorter operating time and greater intra-operative laser efficiency with the Ho:YAG laser over the SPTF laser in mini-PCNL.

Comparative study between a new screwed Amplatz sheath and the ordinary one in percutaneous nephrolithotomy.

OBJECTIVE: The objective of the article is to compare the results of using new screwed Amplatz sheath with results of the conventional Amplatz sheath regarding success and complications during percutaneous nephrolithotomy. METHODS: 100 patients aged more than 18 years with renal calculi more than 2 cm with guy's score 1 from December 2018 till July 2020 were randomly stratified by closed envelope in group A (50 patients) with using conventional sheath and group B (50 patients) with new screwed sheath. We exclude morbid obese patients and patients with contraindication for PNL. RESULTS: There were no significant differences between both groups regarding patients demographic and stone demographic. Operative time and fluoroscopy time were significantly lower in group B rather than group A. Tract stability was in favor of group B as no tract loss recorded while in group A, 5 cases were recorded. In overall complications there were no significant differences between both groups. Bleeding was higher in group A (14%) than in group B (4%), but it was not statistically significant. Success rates were 78% for group A and 88% for group B but it was not statistically significant. CONCLUSION: The screwed Amplatz sheath had showed less operative and fluoroscopy time. Also it enables urologists to have stable PNL tract. So it may be a promising tool to make PNL easier with higher success rate and lower complications.

Cost analysis between mini-percutaneous nephrolithotomy with and without vacuum-assisted access sheath.

PURPOSE: To perform a cost analysis between vacuum-assisted percutaneous nephrolithotomy (vmPCNL) and minimally invasive PCNL (MIP) and explore potential predictors of costs associated with the procedures. METHODS: We analyzed data from 225 patients who underwent vmPCNL or MIP at a single tertiary referral academic center between January 2016 and December 2020. We collected patients' demographics, peri-and postoperative data and detailed expense records. After propensity score matching, 108 (66.7%) vmPCNL and 54 (33.3%) MIP procedures were analyzed. Descriptive statistics assessed differences in clinical and operative parameters. Univariable and multivariable linear regression models tested the association between clinical variables and costs. RESULTS: Operative time (OT) was shorter for vmPCNL, and the use of additional instruments to complete litholapaxy was more frequent in MIP (all p ≤ 0.01). Length of stay (LOS) was longer for MIP patients (p = 0.03) and the stone-free (SF) rate was higher after vmPCNL (p = 0.04). The overall instrumentation cost was higher for vmPCNL (p < 0.001), but total procedural costs were equivalent (p = 0.9). However, the overall cost for the hospitalization was higher for MIP than vmPCNL (p = 0.01). Univariable linear regression revealed that patient's comorbidities, OT, any postoperative complication and LOS were associated with hospitalization costs (all p < 0.001). Multivariable linear regression analysis revealed that LOS and OT were associated with hospitalization costs (all p < 0.001), after accounting for vmPCNL procedure, patients' comorbidities, and complications. CONCLUSION: vmPCNL may represent a valid option due to clinical and economic benefits. Shorter OT, the lower need for disposable equipment and the lower complication rate reduced procedural and hospitalization costs.

Mini Percutaneous Kidney Stone Removal: Applicable Technologies.

Percutaneous nephrolithotomy (PCNL) remains the treatment of choice for large and complex renal stones. The technological advances over the past several decades gave birth to different varieties of minimally invasive PCNLs, including the mini-PCNL, ultra-mini PCNL, super mini-PCNL, and micro-PCNL, with indications being extended to stones even larger than 20 mm. This article provides an update of all these available techniques of miniaturized PCNL along with its anatomic and physiologic impact. This should assist urologists in providing a personalized approach to the patient based on various patient- and stone-related factors to provide the best of all available technology for treatment.

One-Shot Dilatation vs Metal Dilator During Percutaneous Nephrolithotomy in Flank-Free Supine Position: A Randomized Controlled Study.

Background: The creation and dilatation of the nephrostomy tract is a fundamental step in percutaneous nephrolithotomy (PCNL). In one-shot dilatation (OSD), we used a single Amplatz dilator over a central Alken rod. PCNL in the supine position is as effective and safe as in the prone position. The Barts flank-free modified supine position sums several advantages of the different supine positions. We evaluated the efficacy and safety of OSD compared with metal telescopic dilator (MTD) during PCNL while the patient was in Barts flank-free modified supine position. Materials and Methods: Within 2.5 years, 150 patients with kidney stone candidates for PCNL were randomized into two equal groups according to the dilatation technique. In the OSD group, dilatation was performed using a single Amplatz dilator (30F) and in the MTD group dilatation was performed by sequential MTD (9-30F). All PCNL procedures were done with patients in Barts flank-free modified supine position. Patient characteristics, operative data, and results were collected for statistical analysis. Results: There are no statistically significant differences between both groups regarding patients' characters. The tracts were effectively dilated in all patients. Statistical analyses show a significant difference (p ˂ 0.05) between both groups regarding the time of dilatation (seconds; 68 ± 15 vs 147 ± 18), time of X-ray exposure (seconds; during dilatation; 36 ± 10 vs 61 ± 15 and the total; 157 ± 16 vs 181 ± 20), hemoglobin loss (mg/dL; 0.7 ± 0.2 vs 1.2 ± 0.3), and hospital stay (days; 3 ± 0.6 vs 3.7 ± 0.7) with favorable results to OSD. Complication rates were comparable between the two groups. Conclusions: OSD is efficient as MTD during PCNL while patients are in Barts flank-free modified supine position, with less dilatation time, X-ray exposure, blood loss, and hospital stay than MTD.

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

BACKGROUND: A 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. METHODS: PubMed, 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. RESULT: Three 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). CONCLUSION: The 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.

Efficacy and safety of the EMS Swiss LithoClast® Trilogy for PCNL: results of the European multicentre prospective study on behalf of European Section of UroTechnology.

PURPOSE: PCNL requires a lithotrite to efficiently break stones, and some devices include active suction to remove the fragments. We set out to determine the efficacy and safety of the Swiss LithoClast® Trilogy, in a prospective European multicentre evaluation and compared it to published stone clearance rates for Trilogy based on surface area (68.9 mm2/min) and using the 3D calculated stone volume (526.7 mm3/min). METHODS: Ten European centres participated in this prospective non-randomized study of Trilogy for PCNL. Objective measures of stone clearance rate, device malfunction, complications and stone-free rates were assessed. Each surgeon subjectively evaluated ergonomic and device effectiveness, on a 1-10 scale (10 = extremely ergonomic/effective) and compared to their usual lithotrite on a 1-10 scale (10 = extremely effective). RESULTS: One hundred and fifty seven PCNLs using Trilogy were included (53% male, 47% female; mean age 55 years, range 13-84 years). Mean stone clearance rate was 65.55 mm2/min or 945 mm3/min based on calculated 3D volume. Stone-free rate on fluoroscopy screening at the end of the procedure was 83%. Feedback for suction effectiveness was 9.0 with 9.1 for combination and 9.0 for overall effectiveness compared to lithotrite used previously. Ergonomic score was 8.1, the least satisfactory element. Complications included 13 (8.2%) Clavien-Dindo Grade II and 2 (1.3%) Grade III. Probe breakage was seen in 9 (5.7%), none required using a different lithotrite. CONCLUSIONS: We have demonstrated that Trilogy is highly effective at stone removal. From a user perspective, the device was perceived by surgeons to be highly effective overall and compared to the most commonly used previous lithotrite, with an excellent safety profile.

Double-sheath vacuum suction versus vacuum-assisted sheath minimally invasive percutaneous nephrolithotomy for management of large renal stones: single-center experience.

PURPOSE: To compare double-sheath vacuum suction minimally invasive percutaneous nephrolithotomy (DS-mini-PCNL) with vacuum-assisted mini-PCNL (VS-mini-PCNL) and to better define the potential benefits of DS-mini-PCNL. METHODS: Between July 2019 and May 2020, 117 patients with large radiopaque renal stones underwent mini-PCNL. Of these, 63 underwent DS-mini-PCNL and 54 underwent VS-mini-PCNL. For VS-mini-PCNL, a F20 Y-shaped sheath was used and the oblique arm of the sheath was connected to the vacuum suction. For DS-mini-PCNL, the oblique arm of a F20 Y-shaped sheath (the outer sheath) and a F16 Y-shaped sheath (the inner sheath) was connected to the perfusion inflow and the vacuum suction, respectively. A 550-µm holmium-YAG laser was used for stone fragmentation. RESULTS: Compared with VS-mini-PCNL group, DS-mini-PCNL group had significantly shorter operative time (35.78 ± 7.77 min vs. 44.56 ± 13.19 min; P = 0.000) and significantly lower fever rate (1.6% vs. 11.1%; P = 0.048). It was not significantly different between the two groups despite the higher initial stone-free rate seen for DS-mini-PCNL group relative to VS-mini-PCNL group (87.7% vs. 81.5%, P = 0.346). Auxiliary procedure rates were 4.8% (three patients) in DS-mini-PCNL group and 16.7% (nine patients) in VS-mini-PCNL group, with a significant difference (P = 0.034). The difference in the final stone-free rate between the two groups was rendered insignificant (93.8% vs. 89.1%, P = 0.510). CONCLUSIONS: DS-mini-PCNL is a safe and effective modality for large renal stones, which could increase the efficiency of stone extraction and decrease infectious complications compared with VS-mini-PCNL.

Efficacy and safety of modified tract dilation technique using simultaneous pulling of proximal and distal ends of a guidewire for percutaneous nephrolithotomy in modified supine position.

PURPOSE: Recently, the needs for supine percutaneous nephrolithotomy (PCNL) have become more increased because of an easy approach for endoscopic combined intrarenal surgery. However, making a nephrostomy tract during supine PCNL is more difficult than prone position due to movable kidney. To overcome this limitation, we used a modified nephrostomy tract dilation (MTD) technique using guidewire traction. MATERIALS AND METHODS: From January 2014 to June 2019, a total of 259 patients underwent PCNL in the modified supine position. Among them, the MTD technique was performed in 171 patients. For the MTD technique, two hydrophilic guidewires were passed from the nephrostomy tract and brought out through the urethra, then both proximal and distal ends were contralaterally pulled with tension for the easy placement of a fascia-cutting needle and a balloon catheter. We analyzed the efficacy of this technique in comparison with the conventional method. RESULTS: Intraoperative radiation exposure time (RET) (68.87 vs. 212.11 s) and hospital stay (5.90 vs. 6.74 days) were significantly shorter, while the success rate (77.2% vs. 63.6%) was significantly higher in the MTD group. Multivariate analysis showed that only the maximal stone diameter (odds ratio [OR], 1.928; 95% confidence interval [CI], 1.314-2.828; p=0.001) and MTD technique (OR, 0.017; 95% CI, 0.007-0.040; p<0.001) were independent factors for predicting short RET (<120 s). CONCLUSIONS: This study demonstrated that MTD technique can be effectively and safely performed in modified supine position PCNL, and it can be helpful in reducing RET and enhancing success rates.

Effect of Active Aspiration and Sheath Location on Intrapelvic Pressure During Miniaturized Percutaneous Nephrolithotomy.

OBJECTIVE: To evaluate the effects of location of the tip of percutaneous sheath and nephroscope in the collecting system together with active aspiration on the Intrapelvic pressure measurements (IPP) during miniaturized percutaneous nephrolithotomy (miniPNL). MATERIALS AND METHODS: The data of 20 patients underwent miniPNL in supine position was collected prospectively. IPP measurements were done with an 8 Fr urodynamic pressure measurement catheter in 4 different settings with respect to location of tip of sheath and nephroscope. All 4 settings were repeated with active aspiration. Totally measurements were done and compared in 8 different settings for 90 seconds in each patient. RESULTS: Highest mean IPP measurements were recorded in setting II (35.3 ± 11.8 cm H2O) where the sheath was located in the calyx and the tip of the nephroscope was in the renal pelvis. When active aspiration was applied, the mean pressure measurements were significantly lower than the counterpart settings without aspiration (all P values <.0001). When the active aspiration was applied, intrarenal pressure measurements did not exceed 40 cm H2O in any settings in any of the patients. CONCLUSION: Location of the tip of the sheath and the nephroscope has significant effect on IPP measurements. Active aspiration significantly lowers the IPP and keeps it <40 cm H2O. Endourologists should be aware of possible alterations in IPP during miniPNL and active aspiration should be kept in mind as an effective solution to decrease the risk of complications related to high IPP.

Can ultrasound guidance reduce radiation exposure significantly in percutaneous nephrolithotomy in pediatric patients?

In this study, we aimed to compare clinical and technical outcomes between pediatric patients who underwent percutaneous nephrolithotomy (PCNL) under fluoroscopy (FL) and those that underwent this procedure under FL with ultrasound assistance (FLUSA). The data of 66 PCNL patients were analyzed retrospectively. Renal puncture was successful in 22 patients in the FLUSA group and 44 patients in the FL group. In all cases, FL was used for tract dilation and confirmation of ureteral catheter positioning at the beginning of the procedure. The sample consisted of 46 males and 20 females with a mean age of 7.2 ± 2.1 years (range 1-17 years). Stone size varied from 8.0 to 75.4 mm, and 89% of patients achieved a completely stone-free state. The median puncture time was 130.5 ± 25.3 s for FLUSA and 295 ± 82.8 s for FL, the median fluoroscopic screening time was 95 ± 33 and 230 ± 116 s, respectively, and the median radiation dose was 19.04 ± 9.9 dGy/cm2 and 54 ± 21.4 dGy/cm2, respectively. The median puncture time, fluoroscopic screening time, and radiation dose were statistically lower in the FLUSA group (p = 0.001, Mann-Whitney U test). The greatest problem in PCNL is the use of fluoroscopy. Due to some anatomical differences from adults, applying PCNL in pediatric patients using only ultrasound may decrease the success rate. Puncture with ultrasound significantly reduces the radiation dose in children. Puncture with ultrasound and dilation under fluoroscopy is a successful and safe treatment method with low morbidity and high success rates and shorter hospital stay in pediatric patients.

Vacuum-assisted mini-percutaneous nephrolithotomy: a new perspective in fragments clearance and intrarenal pressure control.

PURPOSE: To describe the vacuum-assisted mini-percutaneous nephrolithotomy (vmPCNL) technique performed via the 16Ch ClearPetra sheath, to evaluate its outcomes and to analyze intrarenal pressure (IRP) fluctuations during surgery. METHODS: Data from all consecutive vmPCNL procedures from September 2017 to October 2019 were prospectively collected. Data included patients' and stones characteristics, intra and peri-operative items, post-operative complications and stone clearance. Patients undergoing vmPCNL from March to October 2019 were submitted to IRP measurement during surgery. RESULTS: A total of 122 vmPCNL procedures were performed. Median stone volume was 1.92 cm3. Median operative time was 90 min and median lithotripsy and lapaxy time was 28 min. Stone clearance rate was 71.3%. Thirty-one (25.2%) patients experienced post-operative complications, seven of which were Clavien 3. Postoperative fever occurred in nine (7.4%) patients and one (0.8%) needed a transfusion. No sepsis were observed. IRPs were measured in 22 procedures. Mean IRP was 15.3 cmH2O and median accumulative time with IRP > 40.78 cmH2O (pyelovenous backflow threshold) was 28.52 sec. Maximum IRP peaks were reached during the surgical steps when aspiration is closed (mainly pyelograms), whereas during lithotripsy and suction-mediated lapaxy, the threshold of 40.78 cmH2O was overcome in three procedures. CONCLUSIONS: vmPCNL is a safe procedure with satisfactory stone clearance rates. Mean IRP was always lower than the threshold of pyelo-venous backflow and the accumulative time with IRP over this limit was short in most of the procedures. During lithotripsy and vacuum-mediated lapaxy, IRP rarely raised over the threshold.