Percutaneous Nephrolitholapaxy Research Articles

Intraoperative use of CT-navigation during percutaneous nephrolitholapaxy with the SIEMENS Healthineers’ ARTIS pheno robotic system

Introduction. Percutaneous nephrolitholapaxy (PNL) is the optimal method in the treatment of large or complex renal stones. Surgical equipment and endoscopic equipment, and specialised tools have been constantly developing since the advent of PNL in 1976, increasing success rates with a decrease in the number of complications and morbidity. Owing to the specificity and complexity of the technique, only 11% of urologists in the USA perform PNL, while in Russian Federation no more than 5% of specialists realise it.Objective. To evaluate the possibilities of using a robot-angiograph to create a puncture access.Materials & methods. In the Krasnoyarsk Regional Clinical Hospital in 2021, the first PNL was performed in a patient with a left-sided lower calyx stone using the SIEMENS Healthineers’ ARTIS pheno robotic angiograph in a hybrid operating room. This robotic installation allows the performing of an intraoperative computed tomography examination followed by the construction of a navigation map with a clearly displayed trajectory, length, and angle of inclination of the needle path with automatic positioning of the C-arm.Results. We performed 30 pyelocaliceal punctures using a robotic angiographic installation for PNL. The average age of patients was 56.6 ± 19.0 years. According to MSCT, the lower calyx stone was detected in seven patients, the middle calyx — 13 cases, the upper calyx — seven patients, pelvic stones were recorded in three patients. The density of stones varied from 877 HU to 1356 HU. The use of the ARTIS pheno robotic system allows performing intraoperative 3D modelling to determine the safest pyelocaliceal puncture, followed by PNL, regardless of the stone localisation, the complexity of the anatomy. In addition, a CT-like scans allows you to assess the presence of residual stones during the operation and perform a "second look" not in a delayed manner. This system, unlike all existing types of navigation, allows intraoperative evaluation of the effectiveness (stone-free rate) of surgical treatment.Conclusion. The introduction of this navigation system in PNL will minimise the risks of complications from puncture access, reduce the number of repeated interventions, and minimise undesirable consequences in the postoperative period.

EXPERIENCE OF BILATERAL SYNCHRONOUS PERCUTANEOUS NEPHROLITHOLAPAXY (PCNL)

Objective: This case report will present bilateral synchronous percutaneous nephrolitholapaxy (PCNL) that was performed in Saiful Anwar General Hospital Malang for the first time. Case(s) Presentation: 49 years old male with flank pain on both sides continuously. Non contrast abdominal Computed Tomography (CT) scan showed bilateral pyelum stone and bilateral hydronephrosis. From blood analysis, the creatinine serum was 1.5 mg/dL and ureum serum was level 69.8 mg/dL. Discussion: Bilateral synchronous PCNL was performed in prone position, and stone fragmentation was done with pneumatic lithotripter, the operation last for about 2 hours with minimal amount of bleeding. After 3 months of follow-up, urology ultrasound and abdominal X-ray shows no residual stone, and normal ureum-creatinine level (0.77mg/dL; 43.7mg/dL). Conclusion: Bilateral synchronous PCNL is a safe choice to be done in order to treat bilateral pyelum stone, it can decrease length of stay , total cost therapy, and morbidity of the patient.

Percutaneous nephrolitholapaxy performed under ultrasound and endovisual guidance: evaluation of the factors affecting the immediate outcomes

Introduction. In recent years, ultrasound and endovisual guidance have been introduced into clinical practice when performing percutaneous nephrolitholapaxy.Objective. To identify the most significant factors that influence the frequency of complete elimination of stones and the development of complications in percutaneous nephrolitholapaxy performed under ultrasound and endovisual guidance.Materials and methods. We analyzed the results of the treatment of 515 kidney stone patients who underwent percutaneous nephrolitholapaxy under ultrasound navigation and endovideoscopic guidance using a new method developed by us.Results. The average duration of the operation was 77.2 ± 1.9 min. Most of the operations were performed through one puncture access (95.1%) and in one stage (91.8%) with complete stone elimination in 80.6% of the cases. The degree of decrease in hemoglobin in the postoperative period was only 12.18 ± 0.6 g/l. The frequency of postoperative complications was 29.3%, in most cases there were 1 - 2 severity grades according to Clavien-Dindo. As a result of multivariate regression analysis, independent predictors influencing the frequency of complete stone eradication were the number of stones (p = 0.012), the fact of the presence of staghorn stone (p = 0.016), the number of stages of surgical intervention (p = 0.001). Correlation analysis revealed a statistically significant negative correlation between body mass index and the occurrence of complications (p = 0.005), a positive correlation between the presence of urinary tract infection and the occurrence of complications (p = 0.048), a positive correlation between the grade of blood loss and the occurrence of expectation (р < 0.001).Conclusions. Percutaneous nephrolitholapaxy under ultrasound and endovisual guidance without the use of X-rays is an effective intervention for most patients with kidney stones. Complete stone eradication depends on the number of stones, the presence of staghorn stone, and the number of stages of surgery. The incidence of complications is significantly affected by the body mass index, the presence of urinary infection and the degree of decrease in hemoglobin during surgery.

The Comprehensive Complication Index (CCI) for improved reporting of complications in endourological stone treatment.

The Clavien-Dindo Classification (CDC) lacks a combined score of multiple complications in one patient. The comprehensive complication index (CCI) circumvents this problem making it a valuable instrument to optimize quality control. We aimed to introduce and validate CCI in the treatment of urolithiasis. 60day postoperative complications of 327 consecutive patients undergoing percutaneous nephrolitholapaxy (PNL) and ureterorenoscopy (URS) between 2017 and 2019 were retrospectively assessed and graded according to CDC. CCI was calculated for each patient. Overall morbidity scores of CCI and CDC were compared. Correlation analyses between the two scores and length of hospital stay (LOS) were performed. A multivariate analysis was performed to identify predictive factors for complications. Sample size calculation for an imaginary clinical trial was compared between CCI and CDC. A significant difference in overall morbidity between CCI and CDC was revealed for PNL (p < 0.001) and URS (p = 0.001). There was no statistically significant difference in comparing correlations between cumulative CCI and LOS versus non-cumulative CDC and LOS for both cohorts. Operating time > 90min, maximum stone size, positive preoperative urine culture and PNL type (p < 0.001) were predictive factors for postoperative complications in PNL, while urine culture (p = 0.02) was for URS. Sample size calculation based on CCI resulted in a significant reduction of required patients for PNL (- 48%) and URS (- 84%) compared to CDC. CCI could successfully be validated in endourological stone treatment with the advantage of assessing complications in their entirety compared to CDC. CCI can significantly reduce the required sample size in future clinical trials.

Современные принципы хирургического лечения мочекаменной болезни

The article presents historical data showing the following: how methods for the treatment of urolithiasis have been developed and improved; how endoscopic equipment has been introduced and modernized; how the prevention of postoperative complications and metaphylaxis of recurrent stone formation have changed recently. Approaches to choosing the surgical treatment method depend on many individual factors (localization, concretion size and density, the presence of complicating disease factors) and are personalized. Attention to this problem is focused because of the large number of patients suffering from urolithiasis (at least 3% of the population). Modern diagnostics and treatment technologies are able to sanitize and get rid of the stone of almost any patient, as the working-age population suffers from it, as a rule — these are highly qualified specialists who are forced to be treated for a long time due to urolithiasis complications or relapse. The general social significance of this disease, which can haunt a person throughout life, determines the need to study the pathogenetic mechanisms of stone formation, methods of metaphylaxis and to reduce the number of invasive methods for removing urinary tract concretions, which have many dangerous complications leading to a decrease in working capacity. KEYWORDS: urolithiasis, kidney, surgical treatment, shock wave lithotripsy, ureterorenoscopy, contact ureterolithotripsy, percutaneous nephrolitholapaxy. FOR CITATION: Berezhnoy A.G., Dunaevskaya S.S. Modern surgical methods for the treatment of urolithiasis. Russian Medical Inquiry. 2021;5(3):118–122. DOI: 10.32364/2587-6821-2021-5-3-118-122.

Percutaneous Urolithiasis Surgery in Military

Abstract. The clinical efficacy and safety of the use of percutaneous techniques in the treatment of kidney stones in 72 servicemen were studied. All percutaneous operations were performed by one operating team. It was found that percutaneous urolithiasis surgery was effective in 88.9% of people. Stone free rate was achieved in 83,8% of military personnel undergoing standard percutaneous nephrolitholapaxy and in 94.3% of patients undergoing minipercutaneous nephrolitholapaxy. With stones larger than 2 cm, the effect was observed in 81.8% of cases with standard surgery and in 96% of patients with mini-percutaneous approach. Percutaneous interventions in military personnel with stones larger than 2 cm were effective in 84,6% of patients with standard surgery and in 90% with mini-percutaneous access. Complications according to the Clavien-Dindo classification were found in 29,1% of servicemen: in 20,8% of cases of standard nephrolitholapaxy and in 8,3% of minipercutaneous nephrolitholapaxy. The bulk of the complications were Grade III 20,8%. Grade III IV were determined less frequently in 8,3% of cases. Urosepsis (Grade IV b) and death (Grade V) were not observed in our study. Duration of labor losses for conscripted servicemen were about 17 days, for contract servicemen when performing standard nephrolitholapaxy 12,8 days, for military personnel with minipercutaneous nephrolitholapaxy 11,2 days. The dismissal rate among conscripts was 18,2%. There were no contractual servicemen who were dismissed from the ranks of the Armed Forces of the Russian Federation, however, 14,7% of servicemen who underwent a standard operation and 11,1% of patients who underwent mini-percutaneous nephrolitholapaxy after surgery needed sick leave for a period of 15 days. In general, percutaneous techniques are common and effective methods of surgical treatment for military personnel suffering from urolithiasis. Mini-percutaneous approach for nephrolitholapaxy is safer than the standard approach, but it is less effective for coral calculi. Percutaneous methods for removing kidney stones are associated with a low rate of dismissal and short recovery times for military personnel.

THE ROLE OF DISORGANIZATION OF CONNECTIVE TISSUE AND BASEMENT MEMBRANE OF RENAL TUBULAR EPITHELIUM IN THE PATHOGENESIS OF UROLITHIASIS

According to a number of researchers, pathological changes in the structures of the renal papilla play a key role in the pathogenesis of urolithiasis. According to the results of existing studies, destructive processes in collagen are characterized by a change in the length, thickness of the fibers and their orientation in space. Collagen disorganization has enzymatic and non-enzymatic mechanisms. The aim of the study was to study the frequency and features of localization of Randall's plaques and morphological study of the state of connective tissue and the basement membrane of the epithelium of the renal tubules of different levels in urolithiasis. Microscopically studied preparations of 29 biopsies of renal tissue obtained from patients with fibro-uretero-pyeloscopy (11), percutaneous nephrolitholapaxy (18) and preparations obtained at 20 autopsies in cases without visible renal pathology. Histological preparations were stained with hematoxylin and eosin to determine the state of connective tissue fibers using Van Gieson, Mallory, Schiff-reagent, alcian blue, and Kos for calcifications. The results of the study show that the morphological signs of mucoid swelling of the connective tissue and basement membrane of the epithelium of the renal tubules of different levels in combination with the formation of microcalcifications require further study of the possible role of disorganization of the connective tissue of the renal stroma in the initiation of stone formation in the kidneys.

Quality of life of patients with kidney stones

Relevance. In 2013, the Wisconsin Stone Quality of Life Questionnaire (WISQoL) was developed a specific tool for assessing the quality of life (QoL) in patients with urolithiasis.&#x0D; Aim. To determine the possibility of using the WISQoL and SF-36 questionnaires to study the treatment results of patients with kidney stones.&#x0D; Materials and methods. The study included 218 patients with nephrolithiasis. Patients were divided into 2 groups: the first the size of the stone up to 10 mm and the second from 11 to 20 mm. At the first stage, the efficacy of treatment patients by the extracorporeal shock wave lithotripsy (ESWL) and percutaneous nephrolitholapaxy (PNL) 1 week, 1 and 3 months after surgery was compared. Questionnaires were used to study factors affecting the QOL of patients, including: gender, age, number, density and size of stones, hydronephrosis, stone free rate (SFR), type of surgery. At the next stage, the dynamics of changes in scores for the domains of questionnaires at different stages of treatment was evaluated.&#x0D; Results. The efficacy of treating kidney stones up to 1 cm in size after 3 months with ESWL was 86,1% and PNL 94,4 %, while stones up to 20 mm using ESWL 73,4% and percutaneous techniques 90,6%. Gender, age, stone size, SFR affected the QoL of patients with nephrolithiasis, while the number and density of stones, the presence of hydronephrosis and the type of operation were not significant. Patients 1 week after PNL had lower QoL scores in the domains of social impact and impact on vitalyty of WISQoL and mental heals of SF-36. After 1 month, these changes were determined only in the social impact domain and completely regressed by the 3rd month.&#x0D; Conclusion. SFR after ESWL and PNL in the first group is comparable, in the second group, percutaneous operations were 17,2% more effective. Male gender, age up to 40 years, stone size more than 1 cm, and also not reached SFR negatively affects patients with nephrolithiasis. Compared with ESWL and PNL is accompanied by the worst dynamics of QOL scores only 1 week after the operation; upon further observation, negative changes are leveled.

Supine Percutaneous Nephrolitholapaxy Profile in Jombang General Hospital from 2017 until 2018

Supine Percutaneous Nephrolitholapaxy (sPNL) is a safe, minimally invasive procedure with high success rates and low morbidity for simple or complex kidney stones. This study aims to describe patient profile who underwent Supine Percutaneous Nephrolitholapaxy (sPNL), stone complexity, average length of stay, average time of procedure, stone free rate, the relationship between stone complexity with amount of puncture needed, need of re-nephroscopy, incidence of postoperative complications, and relationship between time of procedure with the incidence of postoperative complication. Analytical retrospective study was performed from February 2017 until May 2018 in Jombang General Hospital. No significant differences were found between stone complexity and number of punctures, need of re-nephroscopy, and post-operative complications. Prolonged procedure related with the incidence of postoperative complications.

Methods for navigating access to the kidney in percutaneous nephrolitholapaxy

<h3></h3> В статье освещены последние данные о методах доступа при перкутанной нефролитолапаксии (ПНЛЛ), а также выявленных преимуществах и недостатках каждого метода навигации. Данные для обзора были собраны в результате поиска в базах данных PubMed и eLibrary, в основных клинических журналах на английском и русском языках. Несмотря на то что ПНЛЛ является методом выбора при крупных камнях почек и мочевыделительной системы, единый подход к методу визуализации еще не разработан. Можно резюмировать, что применение в настоящее время различных методов зависит от оборудования клиники, опыта врача и клинической ситуации. Информация обо всех методах, используемых для пункции мочевыделительной системы почек, является чрезвычайно актуальной и позволит врачам использовать разные подходы в зависимости от клинической ситуации и индивидуальных особенностей пациента.

Experience of treating patients with urolithiasis in the urological clinic of the Aleksandrovskaya hospital

The article presents the experience of treating patients with urolithiasis in the urological clinic of the Aleksandrovskaya hospital. Due to the improvement of technologies, the number of minimally invasive surgeries such as contact ureterolithotripsy, percutaneous nephrolithotripsy and percutaneous nephrolitholapaxy has increased significantly. Performing open surgical interventions is indicated only in complicated cases such as the presence of purulent calculous pyelonephritis. The indication for contact ureterolithotripsy is the localization of concretions in the pelvic ureter, as well as long-term (more than 4 weeks) presence of concretions in any part of the ureter. Percutaneous nephrolitolapaxy is the method of choice in the treatment of urolithiasis in case of uninfected kidney stones smaller and larger than 20 mm in diameter, especially in elderly patients. Emergency contact lithotripsy is indicated for treatment of acute serous obstructive pyelonephritis caused by concretion of any localization. When stones locate in lower calices of kidney effective method is percutaneous nephrolitholapaxy.

Role of pressure and temperature in ureterorenoscopy and percutaneous nephrolitholapaxy : Pressure and temperature changes during stone treatment

Ureterorenoscopy and percutaneous nephrolitholapaxy are minimally invasive procedures and are the standard procedures for the treatment of kidney stones and ureteral calculi. To achieve an adequate view, in both methods an optimal and sufficient irrigation flow is necessary. The intrarenal pressure is influenced by the irrigation pressure and irrigation volume and has to be controlled. Pathologically elevated intrarenal pressure can lead to irreversible damage of the kidneys. Lasers are frequently used for stone fragmentation. It has been shown in studies that the laser energy can lead to an increase in the temperature and that thermal effects can also damage the kidneys. This article provides the surgeon with an overview about the effects of temperature and pressure changes during ureterorenoscopy and percutaneous nephrolitholapaxy and how damages can be avoided.

COMPARISON OF PERITUBAL INFILTRATION OF ROPIVACAIN AND PLACEBO IN PERCUTANEOUS NEPHROLITHOLAPAXY FOR POST OPERATIVE ANALGESIA AT SOETOMO HOSPITAL SURABAYA

Objective: To observe the effects of ropivacain peritubal infiltration in reducing postoperative pain and analgesic requirements postoperatively in patients underwent percutaneous nephrolithotomy (PNL). Material &amp; method: Double blind randomized controlled trial on 32 patients with renal stone who underwent PNL at Soetomo General Hospital Surabaya from February until August 2017, divided into 2 groups. Experimental group (A) who received peritubal infiltration of ropivacain pre-operative, and control (placebo) group (B) Evaluation using Wong Baker pain score 2 hour post operation, time from operation until first rescue analgesia, and total analgesia given in first 24 hours. Result: Mean age was 51.81 ± 9.13 and 49.31 ± 10.53 years in group A and B respectively. Mean operation time 49.31 ± 10.53 and 89.69 ± 17.74 hours in group A and B respectively. There was no significant difference in stone complexity, nephrostomy placement and stenting between two groups. There was no significant difference of Wong Baker pain score 2 hours post operation between group A and B (p 0.72). There was no significant difference in total analgesia in the first 24 hours between group A and B (p 0.48). The time of first rescue analgesia demand was significantly longer in the experimental group (p 0.00). Conclusion: Peritubal infiltration of ropivacain in percutaneous nephrolitholapaxy is safe and effective to prolong the need of first rescue analgesia in post operative pain management which result in patients convenience.

Validation of a Novel Cost Effective Easy to Produce and Durable In Vitro Model for Kidney-Puncture and Percutaneous Nephrolitholapaxy-Simulation.

Nephrolithiasis is one of the most common diseases in urology. According to the EAU Guidelines, a percutaneous nephrolitholapaxy (PNL) is recommended when treating a kidney stone >2 cm. Nowadays, PNL is performed even for smaller stones (<1 cm) using miniaturized instruments. The most challenging part of any PNL is the puncture of the planned site. PNL-novice surgeons need to practice this step in a safe environment with an ideal training model. We developed and evaluated a new, easy to produce, in vitro model for the training of the freehand puncture of the kidney. Porcine kidneys with ureters were embedded in ballistic gel. Food coloring and preservative agent were added. We used the standard imaging modalities of X-ray and ultrasound to validate the training model. An additional new technique, the iPAD-guided puncture, was evaluated. Five novices and three experts conducted 12 punctures for each imaging technique. Puncture time, radiation dose, and number of attempts to a successful puncture were measured. Mann-Whitney-U, Kruskal-Wallis, and U-Tests were used for statistical analyses. The sonography-guided puncture is slightly but not significantly faster than the fluoroscopy-guided puncture and the iPAD-assisted puncture. Similarly, the most experienced surgeon's time for a successful puncture was slightly less than that of the residents, and the experienced surgeons needed the least attempts to perform a successful puncture. In terms of radiation exposure, the residents had a significant reduction of radiation exposure compared to the experienced surgeons. The newly developed ballistic gel kidney-puncture model is a good training tool for a variety of kidney-puncture techniques, with good content, construct, and face validity.

Extracorporeal shock wave lithotripsy

Interventional treatment of stones essentially consists of three treatment modalities. Extracorporeal shockwave lithotripsy (ESWL), in addition to uterorenoscopy (URS) and percutaneous nephrolitholapaxy (PCNL) is an essential treatment pillar and is the only noninvasive therapy option for the treatment of urinary stones. After along period of ESWL being the leading choice in stone treatment, the number of SWL interventions diminished in recent years in favor of the other two treatment modalities (URS and PCNL). This article describes the indications, surgical technique and management of complications of SWL.

EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY;

Background: Urolithiasis is a common ailment that costs billions of Dollars everyyear. Recurrent urinary tract obstruction or urolithiasis may stimulate the fibrogenic flow, whichis responsible for the definite functional loss of renal parenchyma. In the few past years, themanagement of urinary calculi undertook a remarkable modification. Open surgery for stonesis nearly replaced by minimal or non-invasive operative procedures like ureterorenoscopy,percutaneous nephrolitholapaxy and extracorporeal shock wave lithotripsy (ESWL). StudyDesign: Randomized Controlled Trial. Setting: Department of Urology Services HospitalLahore. Duration of Study: 1st January -30th December 2016. Material and methods: Thecomparative study of 60 cases through Non probability convenient sampling was conducted toevaluate the outcome of ESWL in patients with single lithiasis of lower pole calyx with differentinfundibulopelvic angles as measured on pre-treatment IVU. Results: The mean age of all thepatients was 33.70±10.72 years. Out of 60 Patients 32(53.3%) were males while 28(46.7%)were females with 1.14 male to female ratio. In group A, the mean LIPA was 78.83±4.71o andin group B, was 100.53±5.73o. The overall mean LIPA of the patients was 89.68±12.11o.Stoneclearance was noted in 39 (65%) patients. 15 patients (38.46%) and 24 patients (61.53%) ingroup A and B respectively. p-value=0.015. After ESWL stone clearance was more in patientshaving IPA ≥ 90°as compared to IPA 70-90o. Conclusion: Stone clearance is significantlyhigher with IPA&gt;90o as compared to IPA70-90o.In future now we are able to implement the useof IPA&gt;90o instead of using &lt;90o that is more successful in achieving stone clearance.

559 - CT-controlled stone-free-rate after minimal-invasive percutaneous nephrolitholapaxy (MIP) in correlation with instrument-size

559 - CT-controlled stone-free-rate after minimal-invasive percutaneous nephrolitholapaxy (MIP) in correlation with instrument-size

Uncovering the real outcomes of active renal stone treatment by utilizing non-contrast computer tomography: a systematic review of the current literature

To evaluate the stone-free rates (SFRs) and stone clearance rates (SCRs) of extracorporeal shock-wave lithotripsy (SWL), retrograde intrarenal surgery (RIRS), and percutaneous nephrolitholapaxy (PCNL) according to non-contrast computer tomography (NCCT) findings. Original articles were identified from PubMed. After exclusion of ineligible papers, twenty-three studies with 2494 cases were included in the review. Six SWL, five RIRS and eight PCNL studies were selected. Additionally, four comparative articles were identified. SWL presents SFRs ranging 35-61.3% and SCRs for residuals <4mm being 43.2-92.9%. RIRS studies report SFRs of 34.8-59.7% and SCRs for residuals <4mm ranging 48-96.7%. Finally, PCNL presents SFRs of 20.8-100% and SCRs for residuals <4mm being 41.5-91.4%. According to the comparative studies, SFRs are 17-61.3% for SWL, 50% for RIRS, and 95-100% for PCNL. According to NCCT findings, it seems that PCNL provides better SFRs than ESWL and RIRS. However, further research with comparable and complete preoperative parameters and outcomes could reduce the heterogeneity of current data.

Морфометрическое моделирование как фактор, улучшающий результаты перкутанной нефролитолапаксии

Морфометрическое моделирование как фактор, улучшающий результаты перкутанной нефролитолапаксии

The vacuum cleaner effect in minimally invasive percutaneous nephrolitholapaxy.

Percutaneous stone removal increasingly plays an important role among the different approaches of interventional stone therapy, particularly since the development of miniaturized instruments is resulting in lower morbidity for the patients. One major drawback of smaller instruments is the increased difficulty of stone retrieval after disintegration due to the reduced tract diameter. This results in longer operation time and the need of additional tools such as disposable retrieval baskets. One of the key factors in the development of minimally invasive percutaneous nephrolitholapaxy (MIP) was the design of an Amplatz sheath which provides a built-in vacuum cleaner effect for stone retrieval. A series of flow analyses with the gauges and shapes of the most commonly used nephroscopes and sheaths in percutaneous nephrolitholapaxy was performed by computational fluid dynamics. Flow velocity and direction in front of the nephroscope were computed and visualized by the software. In our study, the vacuum cleaner effect developed exclusively when a round-shaped nephroscope was used (Nagele Miniature Nephroscope System, Karl Storz GmbH & Co. KG) and depended on the relation between nephroscope diameter and inner sheath diameter. The strongest effect was observed with a 12 F nephroscope and an inner sheath diameter of 15 F. It did not develop when an oval- or crescent-shaped nephroscope was used. In front of the distal end of the round-shaped nephroscope, a slipstream develops, induced by the excursive change of width of the fluid flow on the outlet of the flushing canal. This allows the adhesion of a stone fragment in the eddy while the fluid flow is circulating around the stone. This study illustrates and explains the vacuum cleaner effect which has been detected in the development of the Nagele Miniature Nephroscope System used in MIP. It combines the reduced morbidity of smaller kidney puncture diameters with the benefit of quick and complete stone removal.