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Introduction. The emergence of new scientific and clinical evidence on the use of retrograde intrarenal surgery (RIRS) for the management of kidney stones has prompted periodic systematisation, analysis, and evaluation of outcomes to standardise its application and determine future directions for research and development.Objective. To present the Russian adaptation of a guideline on retrograde intrarenal surgery from the International Urolithiasis Alliance guideline series to provide a theoretical basis for urologists performing RIRS.Materials & Methods. A systematic review was conducted on the RIRS-associated publications available in the PubMed database to prepare a set of recommendations during the period from 1 January 1964 until 1 October 2021. The recommendations were evaluated using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) system, which classifies, evaluates, develops, and examines recommendations. The modified Oxford Centre for Evidence-Based Medicine's (OCEBM) system for categorising the level of evidence and relevant comments have been applied to assess the strength of the conclusions.Results. The research team conducted a comprehensive analysis of 36 published clinical guidelines on the following topics: 1. Indications and Contraindications 2. Preoperative Imaging 3. Preoperative Ureteral Stenting 4. Preoperative Medications 5. Perioperative Use of Antibiotics 6. Use of Antithrombotic Therapy 7. Anesthesia Issues 8. Intraoperative Positioning 9. Equipment 10. Complications.Conclusion. A series of recommendations for RIRS, offered here should help provide safe and effective performance of RIRS.

Introduction. Urolithiasis is one of the most widespread urological diseases and infectious complications remain one of the most common adverse events after surgical interventions for urolithiasis. Currently, in routine clinical practice in most clinics in the country, for the purpose of postoperative control and detection of infectious complications is used: a clinical blood test with assessment of the dynamics of the blood leukocyte count. Unfortunately, the current edition of the clinical guidelines does not contain recommendations on what indicators of postoperative follow-up examinations the clinician should focus on in order to identify infectious and inflammatory complications. For this reason, the study of the value of other markers of the inflammatory response appears to be an actual task.Objective. To assess the relationship between the dynamics of laboratory markers of infectious-inflammatory complications and the incidence of infectious-inflammatory response after endoscopic stone removal.Materials & methods. The prospective cohort study included 217 patients diagnosed with urolithiasis and underwent surgical removal of stones by endoscopic method. Of total patient numbers, 43 patients underwent ureteroscopy (URS) with lithotripsy, 152 patients underwent percutaneous nephrolithotripsy (PNL), and 22 patients underwent flexible ureterolithotripsy with lithotripsy. An analysis of demographics, clinical parameters and postoperative complications was performed as a descriptive analysis. Patients underwent a standard list of laboratory and instrumental examination methods. The mandatory control of body temperature was carried out t.i.d. daily. Before surgical treatment, indicators of WBC, LYMP, CRP, and ESR content were recorded on the first and second days after surgical treatment.Results. Postoperative fever was recorded in 40 (18.5%) patients. During the postoperative period, an increase in CRP and ESR was observed in both the fever and the normal temperature group, exceeding the reference values on the first day. At the same time, in the fever group (in 40 patients — 18.5%), a significantly higher increase in CRP and ESR was observed (685% vs 323%) for CRP and (146% vs 80%) for ESR. According to the results obtained in our study, CRP and ESR indicators demonstrate the most clinically significant dynamics in patients with postoperative fever, increasing by more than 500% and 100%, respectively.Conclusions. Endoscopic removal of urinary stones is a safe treatment option in patients with sterile urine cultures. After endoscopic stone removal, all patients experience such reactive changes in peripheral blood parameters as: an increase in the level of leukocytes, lymphopenia, an increase in ESR and CRP levels. Indicators of CRP and ESR demonstrate the most clinically indicative dynamics.

Introduction. According to the guidelines, the stone maximum diameter is one of the main criteria for choosing the method of nephrolithotripsy. When planning an operation, the surgeon focuses not only on the diameter, but also on the renal pelvis anatomy, stone density and number of it, the presence of hydronephrosis, a history of surgery, etc. The maximum diameter is not an exhaustive characteristic that allows you to choose the optimal treatment.Objective. To evaluate the effect of stone volume (compared to its maximum diameter) on the duration of minimally invasive endoscopic nephrolithotripsy.Materials & methods. The study was retrospective. The study included 55 patients (22 women, 33 men), the average age was 47.0 ± 1.9 years. All patients underwent minimally invasive thulium fiber laser nephrolithotripsy for stones up to 20 mm (mean maximum diameter — 13.3 ± 0.6 mm, mean density — 1041.0 ± 48.0 HU). Minimally invasive endoscopic interventions such as retrograde intrarenal surgery (RIRS, n = 30), minipercutaneous and micropercutaneous nephrolithotripsy (miniPNL, n = 16 and microPNL, n = 9, respectively) were performed. Patients with urinary system abnormalities, acute urinary tract infections and patients without stone-free status were excluded from the study. In addition to evaluating standard indicators, the stone volume was calculated in all patients using the formula of a scalene ellipsoid (median volume — 287 [144; 538] mm3). Spearman's rank correlation coefficient (r) with an assessment of the significance level was calculated for the stone maximum diameter and volume for the total sample of patients and for each surgical intervention method separately.Results. The analysis of the total sample of patients reliably revealed a weak correlation (r = 0.39) between the stone maximum diameter and surgery time. And a moderate correlation was found between the stone volume and surgery time (r = 0.53). A similar relationship with the linear distribution was also observed in the analysis in all groups.Conclusion. When choosing minimally invasive laser nephrolithotripsy, it is advisable to focus not only on the stone maximum diameter, density, and localisation, but also on the stone volume, which has a great correlation with the surgery time.

The choice of surgical treatment for nephrolithiasis remains a matter of debate. The article is a literature review dedicated to a comparative analysis of the efficacy and safety of extracorporeal shock-wave lithotripsy (ESWL) and endoscopic methods for the treatment of nephrolithiasis. The literature review was based on the analysis of articles published in the PubMed / MEDLINE, and eLibrary databases. Sixty publications on the topic of the review were analysed. As a result of data analysis, endoscopic therapies have a significant advantage over ESWL with comparable safety. The development and dissemination of less invasive techniques such as mini-percutaneous nephrolithotripsy and ultra-mini-percutaneous nephrolithotripsy in the future may change the approach to the surgical treatment of any form of nephrolithiasis.

Objective: To determine the surgical possibilities of the one-stage laparoscopic repair in the obstructed ureteropelvic junction (UPJ) complicated with nephrolithiasis in combination with the retrograde intrarenal surgery.Case report: The patient A., a 36-year-old male complaining about dragging pains in the right lumbar region was admitted to Urology Unit No. 1 of Krasnodar Regional Clinical Hospital No. 2. The patient underwent ultrasound examination, CT, and dynamic renal scintigraphy. The findings were as follows: the enlargement of pelvicalyceal system in the right kidney (calyx up to 22 mm, pelvis up to 50 mm), 5 calyx concrements and 2 pelvic concrements 6 to 8 mm in size, obstruction at the level of the right UPJ up to 10 mm in length, III grade hydronephrosis on the right according to Lopatkin classification.Conclusions: The combination of laparoscopic surgery and retrograde intrarenal surgery with the flexible ureteroscope and holmium laser is an effective and safe method for the treatment of UPJ obstruction complicated with nephrolithiasis.

Introduction: Retrograde intrarenal surgery (RIRS) alongside percutaneous surgery is gaining a leading position in the nephrolithiasis treatment. According to 2022 EAU Guidelines, RIRS is one of the basic surgical modalities to treat 10-20 mm kidney concrements. Turning concrements into dust, holmium laser is the most effective and safest method for concrement disintegration.Objective: To determine surgical possibilities of holmium laser lithotripsy for single and multiple unilateral nephrolithiasis using disposable flexible ureterorenoscopes.Materials and methods: We performed 124 interventions from October 2021 to October 2022 using LithoVue flexible ureterorenoscope in patients with nephrolithiasis, of them 70 males and 54 females with the mean age being 54 (27–74) years. Patients were divided into 2 groups: group I (56 patients) with a single renal concrement, group II (68 patients) with multiple concrements (2 to 7 pieces). The concrement size ranged from 5 to 20 mm. The density of kidney concrements on computed tomography (CT) was 214 to 1,620 HU. LightTrail 230 μm and 270 μm reusable laser fibers were chosen for Auriga XL holmium laser crushing mode. Laser operating settings were as follows: frequency 8 Hz, pulse energy 1,200 mJ (LightTrail 230 µm) and frequency 12 Hz, pulse energy 1,800 mJ (LightTrail 270 µm). These are the maximum setting values for the specific laser fibers.Results: Average time of 1 concrement disintegration (V = 1 cm3) was 28.3 minutes. Concrement disintegration time was 21.4 ± 6.7 minutes (group I) and 42.3 ± 9.4 minutes (group II). Intervention time was 27.4 ± 8.3 minutes (group I) and 54.6 ± 12.4 minutes (group II). In-hospital stay was 2.5 ± 1 days (group I) and 3 ± 1 days (group II). The rate of surgical success according to CT scans was 92.6% (group I) and 88.2% (group II). Two patients in group I and 5 patients in group II required reintervention. One patient (1.8%) in group I and 3 patients (4.4%) in group II developed an acute pyelonephritis (Clavien-Dindo classification, grade II). In the remaining patients the complications did not exceed Clavien-Dindo grade I. There were no equipment-related issues in the perioperative period.Conclusions: As a safe and effective procedure with low complication rate, fast postoperative recovery, and short hospital stay, RIRS can be used as a method of choice for disintegration of kidney concrements up to 20 mm in size.

Urolithiasis is one of the most common urological conditions (30–45 %), peaking in the 4th–6th decades of life. About 50 % of patients have one recurrent episode of nephrolithiasis during their lifetime, and among the operated patients, more than 10–15 % of individuals report recurrences with the need for repeated surgical treatment. Increasing the incidence of nephrolithiasis in the world requires the development of new and improvement of existing methods of surgical treatment, which would be characterized by a high level of efficiency and low invasiveness with minimal complications and postoperative rehabilitation. The use of a combination of percutaneous nephrolithotripsy and flexible ureteronephrolithotripsy, especially in complex cases of urolithiasis, can increase the safety and improve the treatment of nephrolithiasis by combining the positive qualities of both methods. Aim. To summarize the data of the world scientific literature on the treatment of nephrolithiasis by studying a combination of percutaneous nephrolithotripsy and retrograde or antegrade flexible intrarenal surgery based on the evaluation of their effectiveness and safety. Materials and methods. The literature review was conducted using the databases PubMed, Google Scholar, Web of Science and Scopus for the period 2015–2022. The following keywords were used for the search: surgical treatment of nephrolithiasis, endoscopic combined intrarenal surgery (ECIRS), percutaneous nephrolithotomy, retrograde intrarenal surgery, simultaneous use of flexible ureterorenoscopy and percutaneous nephrolithotomy, simultaneous use of flexible ureterorenoscopy and percutaneous nephrolithotripsy. Conclusions. The use of ECIRS increases the effectiveness of one-stage treatment of nephrolithiasis with minimal complications and reduces the number of re-operations required. Treatment of complex forms of nephrolithiasis may be a priority for ECIRS. The main disadvantages of ECIRS are the need for simultaneous operation of two operating surgeons and the availability of two sets of endoscopic equipment, which make this procedure expensive.

According to the guidelines, percutaneous nephrolithotomy is the main treatment for patients with kidney stones larger than 2 cm. However, many studies have recently been published describing the safety and efficacy of retrograde intrarenal surgery (RIRS) in the treatment of patients with kidney stones of similar size. This paper reviews the literature on the use of RIRS in the treatment of patients with kidney stones larger than 2 cm. The study aims to evaluate the safety and efficacy of RIRS in the treatment of kidney stones larger than 2 cm. Such indicators as the duration of surgical treatment, stone-free rate, intra- and postoperative complications were evaluated. Also, the history of the development of ureteroscopy as a diagnostic and therapeutic method for diseases of the upper urinary tract is briefly reviewed. The material was searched in the PubMed, Scopus, Web of Science, and Google Scholar databases.

Abstract Introduction and aim of the study: Urolithiasis is a disease involving the formation of deposits in the lumen of the urinary tract. The continued development of minimally invasive treatment methods allows for more effective treatment with greater operator comfort and less risk to the patient. It has been concluded that retrograde intrarenal surgery (RIRS) is superior to other therapeutic methods in many respects. The aim of this study is to review the available studies and publications and to identify potential complications following treatment of kidney and ureteral stones by RIRS, with a particular focus on infectious complications and their risk factors. Method and materials: We reviewed the literature available on PubMed and Google Scholar, using the words 'urolithiasis'; 'urolithiasis treatment'; 'retrograde intrarenal surgery'; 'infectious complications of retrograde intrarenal surgery'. Results: Among the risk factors associated with infectious complications after RIRS, long duration of surgery, recent positive urine culture, urinary tract infections or antibiotic use, purulent urine, urinary nitrites, obstructed access through the ureter, struvite stones, co-morbidities play a special role. Conclusions: Among the complications of surgical treatment of nephrolithiasis and ureteral stones by RIRS, infectious complications are of particular concern. In view of the knowledge of their risk factors, preventive measures should include limiting the duration of surgery, possible antibiotic therapy and considering the use of a larger diameter UAS. This is especially true for patients with abnormal urine results, struvite stones, a history of urinary tract infection or predisposing comorbidities. Key words: Urolithiasis; Kidney Calculi; Retrograde Intrarenal Surgery; Urolithiasis infection;

Kidney stone disease (KSD) is a disease caused by the formation of calculi in kidneys and other parts of the urinary tract. The rate of hospitalization of children with KSD worldwide is increasing. The adequate method of calculus extraction and further therapy according to calculus composition and metabolic disorders are crucial for effective treatment of patients with KSD and recurrence risk reduction. This review covers surgical (extracorporeal lithotripsy, percutaneous nephrolithotripsy, retrograde intrarenal surgery, ureterolithotripsy, laparoscopy, open surgery) and non-surgical (lithokinetic and litholytic) therapy. Special attention is paid to metaphylaxis, or recurrence prevention, and calculi formation. It is noted that medication of children with KSD can be aggravated by various adverse reactions, complexity in drugs dosages in children of first years of life. Moreover, all surgical methods are characterized by high risk of postoperative complications development. The relevance of KSD genetic nature in children, the role of lifestyle changes in disease development, the implementation of new drugs for metabolic disorders correction are presented in the article.

Objective To evaluate the results of extracorporeal shockwave lithotripsy (ESWL) versus retrograde intrarenal surgery (RIRS) for the treatment of calcium oxalate nephrolithiasis, as well as the damaging effects on renal function, taking into account the dynamics of blood cystatin C and urine beta2-microglobulin.Material and Methods Of 94 patients with calcium oxalate nephrolithiasis aged 23–78 included in the study, 42 patients were classified as having undergone ESWL (group I) and 52 patients as having undergone RIRS (group II). Group II patients were then stratified into subset 2A (n = 32) as having undergone RIRS through rigid ureteroscope and subset 2B (n = 20) as having undergone RIRS through flexible ureteroscope. We performed plain urography and nephrosonography at 24–48 hours postoperatively and unenhanced computed tomography 4–6 weeks after surgery. We measured concentrations of serum cystatin C and urinary beta2-microglobulin as a marker for kidney damage. In group I, samples of peripheral blood andurine were taken before and after the first, third sessions and 30 days after the last ESWL session. In group II, samples were analyzed before surgery, on the first and 30th postoperative days.Results The average size of calculi in the group with RIRS was 16.91 ± 2.79 mm, in the group with ESWL 12.31 ± 2.27 mm. The need for reoperation after RIRS was 19.2%, which was lower than after ESWL. Stone-free effect (no stones, or residual stones less than 3 mm) was observed in 95% of cases in patients with RIRS, and in 78% with ESWL. Group I patients demonstrated an increase in the blood leukocytes total number more often than subsets 2A (rigid RIRS) and 2B (flexible RIRS) patients. Leukocyturia was also a more common complication in group I. In the RIRS group, there was no statistically significant change in the level of blood cystatin C and urine beta2-microglobulin, on the contrary, a moderate increase in the endogenous marker of cystatin C was noted after one ESWL session. The increase in urine beta2-microglobulin levels in patients after the first and third ESWL sessions was significantly higher than after RIRS.Conclusion Flexible RIRS may be suggested as the preferred procedure for patients requiring additional protection of renal function in the treatment of renal stones less than 20 mm. ESWL of stones less than 20 mm can be used as an alternative treatment, since it is characterized by a rather long period of stone eradication from the urinary tract, a high frequency of residual calculi after the procedure, and also has a damaging effect on the renal tissue.

Background. The incidence of kidney stone disease (KSD) in children varies from 1% to 5%. Pediatric surgery of KSD employs methods similar to surgical technologies used for adults: extracorporeal shockwave lithotripsy (ESWL), ureterolithotripsy (ULT), retrograde intrarenal surgery (RIRS), percutaneous nephrolithotomy (PCNL), open and laparoscopic lithotomy. ESWL remains the method of choice for urolithiasis management in children; however, the number of publications describing application of minimally invasive procedures (PCNL, RIRS) for large stones in children is increasing. The said existing tendency determines the need for a comparative study in order to reveal the efficiency and safety of ESWL and PCNL/RIRS as treatment methods for large stones in children.Objectives. The study results of the ESWL use in the treatment of children with stones greater than 2 cm.Materials and methods. During the period from 2013 through 2018, ESWL was performed for 146 patients (70 (47.9%) boys and 76 (52.5%) girls) to treat 170 stones. Age of the patients: 6 months to 17 years (mean age: 73 months). Stones were found on the left side in 96 (61.1%) patients, on the right side — in 58 (38.8%) cases, bilaterally — in 16 (9.41%) children. Large stones exceeding 2 cm were diagnosed in 16 patients (8 (50%) boys and 8 (50%) girls). Urolithiasis was revealed on the right side in 3 (18.7%) patients, on the left side — in 11 (68.7%) cases, bilaterally — in 2 (12.5%) children. All patients were subdivided into 2 subgroups: Subgroup I — 6 (37.5%, 7 kidneys) patients with staghorn urolithiasis, Subgroup II — 10 (62.5%, 11 kidneys) patients with non-staghorn stones. Postoperative complications were evaluated in accordance with the Clavien-Dindo classification.Results. In Subgroup I, complete elimination of C-1 stones in one patient took two ESWL sessions (16.67%). Three (50%) children needed 3 ESWL sessions. One (16.67%) child underwent 4 fragmentations. One (16.67%) patient with bilateral C-2 stones had 2 ESWL on the right side, 2 ESWL of the left-side calculus, and 1 ESWL session of stone fragments in distal ureter with prior insertion of ureteral catheter. In Subgroup II, a single ESWL session was sufficient to eliminate a calculus completely in 3 cases (30%). 2 patients (20%) had to undergo two ESWL sessions. 3 patients (30%) needed three ESWL sessions. Four ESWL sessions were carried out for one child (10%). One patient with bilateral stones underwent 2 sessions on the left side, 3 sessions on the right side, the child also had an ESWL to correct the steinstrasse condition in the lower third segment of the left ureter. Grade IIIb postoperative complications according to the Clavien-Dindo classification were observed in 1 (14.9%) patient of Subgroup I and in one (9.09%) patient of Subgroup II. No lithogenesis recurrences were registered.Conclusions. In cases of children suffering from concrements larger than 2 centimetres, ESWL is a safe and efficient procedure even without prior urine derivation resulting in lower incidence of complications compared with other minimally invasive KSD treatment technologies.

Aim: To improve the results of treatment of patients with urolithiasis who underwent endoscopic interventions using a ureteral access sheath (UAS) by developing a predictive model of ureteral dilatation without pre-stenting., Materials and Methods: A total of 180 patients with kidney stones up to 20 mm were included in the study. They were divided into two groups: in the group 1 (n=79) UAS of 12/14 Ch was used, while in group II (n=101) UAS of 10/12 Ch was inserted. In group I, 48 (60.8%) patients underwent micropercutaneous nephrolithotomy and in 31 (39.2%) retrograde intrarenal surgery was done, compared to 42 (41.6%) and 59 (58, 4%) of patients in group 2. A non-inclusion criterion was a history of ureteral stenting. At the stage of preoperative diagnosis, 60 minutes before the X-ray examination, the patient took a single dose of 80 mg of furosemide per os to improve visualization of the upper urinary tract. After digital processing of computed tomography data and 3D-reconstruction of the upper urinary tract using the DICOM image processing program "RadiAnt DICOM Viewer," a visual assessment of the ureter was carried out to exclude significant deviations and strictures. The ureteral width was measured at three points: pyeloureteral segment, the level of the iliac bifurcation and intramural part. The number of cases of successful insertion of UAS and the rate of damage to the ureteral wall according to the classification proposed by O. Traxer and A. Thomas (2012) were analyzed. The prediction of successful insertion of a UAS was carried out using ROC analysis., Results: In group 1, successful insertion of UAS was observed in 37 (46.8%) patients compared to 84 (83.2%) patients in group 2. In the remaining 42 (53.2%) and 17 (16.8%) cases, respectively, placement of UAS was not possible due to significant tissue resistance and high risk of traumatic injury. The average ureteral diameter at the points of physiological narrowing in patients with successful insertion of 12/14 Ch UAS were 2.0+/-0.1 mm, compared to 1.2+/-0.4 mm in those with failed insertion (p<0.05). In the group 2, similar indicators were 1.6+/-0.1 mm and 1.2+/-0.5 mm, respectively (p<0.05). According to ROC analysis, the diagnostic efficiency of the predictive model when using 12/14 Ch and 10/12 Ch UAS was confirmed by high AUC values (0.925 [95% CI 0.871-0.98] and 0.944 [95% CI 0.89=0.97], respectively). The total number of patients with ureteral injuries was 35 (44.3%) and 40 (39.6%) in groups with 12/14 Ch and 10/12 Ch UAS, respectively. At the same time, complications of the I degree were observed in 24 (30.4%) patients of the group 1 and in 31 (30.7%) patients of the group 2, while injuries of II degree were detected in 10 (12.7%) and 9 (8.9%) cases, respectively (p>0.05). Only in 1 (1.3%) patient, when 12/14 Ch UAS was inserted, grade III damage to the ureteral wall was determined., Conclusion: The proposed technique for measuring the cross-section of the ureter allows to predict the successful insertion of UAS at the preoperative stage. The probability of successful passage of UAS of 10/12 and 12/14 Ch in patients with ureteral diameter in physiological narrowings of more than 1.6 mm and 2 mm, respectively, is 95%. An insertion of UAS is a safe procedure, and most complications are classified as grades I or II.

Introduction: One of the main trends in the evolution of endoscopic treatment of urolithiasis is the miniaturization of instruments. This is obvious in the development of minimally invasive percutaneous nephro-lithotomy (PCNL) and retrograde intrarenal surgery (RIRS). However, there are few studies comparing the efficiency and safety of these methods., Aim: To evaluate and compare the efficiency and safety of mini-PCNL, micro-PCNL and RIRS in the treatment of kidney stones up to 2 cm in size., Materials and Methods: Between October 2020 and December 2022, a total 72 patients underwent minimally invasive endoscopic procedures in two centers, including RIRS (n=30), mini-PCNL (n=26) and micro-PCNL (n=16) using thulium fiber laser FiberLase U2. The efficiency of procedure (stone free rate [SFR]) was assessed using non-contrast-enhanced CT. SFR was considered as the absence of residual fragments > 4 mm. Complications (safety) were evaluated based on the Clavien-Dindo classification., Results: The mean age of all patients was 47.7 (22-84) years. There were no significant differences between three groups in stone characteristics according to CT (maximum diameter, density, volume and number of stones, the presence of pelvicalyceal dilation). SFR was significantly different between the groups (p=0.034). The overall SFR was 81.9% (n=59). After RIRS, mini-PCNL, and micro-PCNL the SFR was 93.3%, 80.8%, and 62.5%, respectively. A significant difference was found between the RIRS and micro-PNL groups, with 2 out of 30 and 6 out of 16 patients requiring repeat procedure, respectively (p=0.026). The overall rate of complication of grades I-II, IIIa and IIIb according to Clavien-Dindo was 6.9%, 9.7% and 6.9%, respectively. A significant difference was found between the RIRS and micro-PCNL (p=0.021) for grade I-II complications. A rate of grade III complications was not differed between the groups. The operation time was higher for mini-PNL (79.8 (30-145) min), and it was shorter for RIRS (55.7 (30-155) min). The length of stay was lower in RIRS group (4.5 (1-12) days)., Conclusion: The highest SFR was achieved in the RIRS group. In terms of the number of complications of I-II grades according to Clavien-Dindo, the duration of the procedure and the length of stay, RIRS also showed the advantage. There were no significant differences in efficiency and safety between the micro-PNL and mini-PNL. There are not enough studies comparing minimally invasive methods for treating kidney stones. It is necessary to continue research in this area in order to develop an optimal algorithm for choosing the method of endoscopic treatment.

The clinical examples of the use of modern endoscopic minimally invasive technologies in patients with urinary tract anomalies and in complex clinical cases are presented in the article. The techniques and features of percutaneous nephrolithotomy, retrograde intrarenal surgery (RIRS), antegrade ureteroscopy using f lexible scope in this category of patients are discussed. The paper confirms the efficiency and necessity of further development of endourological methods for the treatment of urolithiasis.

The aim of research was to study the place of retrograde intrarenal surgery in the treatment of kidney stones, especially those larger than 2 cm in the enderly. In the work, threre were studied retrospectively the medical histories of 17 patients who underwent flexible ureterorenoscopic lithotripsy for renal stones during the period 2014-2018 in the Hospital of the Ministry of Internal Affairs and private clinic. In the postoperative period, there were studied the following indicators: stone free rate (SFR), complications rate, duration of hospital stay and changes of blood tests. Residual fragments are considered to be stones larger than 4 mm. In 17 patients, flexible ureterorenoscopic lithotripsy was conducted because of kidney stones. The average size of kidney stones is 28,4±3,3 mm. In 3 patients out of 17 the ipsilateral urinary stones were also found along with kidney stones. In a control examination a month later, the stone free in patients with kidney stones was 82,4%. The duration of hospital stay was 1,07 days on the average. In 2 patients (11,8%) there were complications of the 1st and 2nd degrees, according to Clavien classification. In the treatment of patients with kidney stones, especially those in the lower pole, and with ipsilateral urinary stones, the RIRS method can be considered the most effective. Even in patients with kidney stones more than 2 cm, the higher stone free rate can be achieved.

Retrograde intrarenal surgery (RIRS) is a rapidly developing field of endoscopic management of urolithiasis. Previously considered an additional technique in patients with lower calyx stones that do not respond to extracorporeal shock wave lithotripsy, now the RIRS along with percutaneous surgery is gaining a leading position in the management of kidney stones. Currently, it is recommended as the main surgical modality for treating stones less than 2 cm, especially in cases where extracorporeal shock wave lithotripsy is not feasible or not desirable. Retrograde intrarenal surgery has no specific contraindications, except for the active inflammatory process in the urinary tract, and can be used even in patients with various coagulopathies. In this paper, we present information on the history of the emergence and advances of RIRS, indications and contraindications, preoperative patient care, the choice of anesthesia, the surgical technique and features of the ureteral sheaths, strings, and lithoextractors. Recommendations for laser lithotripsy, postoperative care and possible complications with a review of the current literature are presented.