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1 INTRODUCTION Kidney stone are the most common pathology in all sites on the urinary tract Although treatment of kidney stons has been progressive, but still challenging for urologists Open surgery to remove stone only accounts for less than 10% in developed countries The incidence of residual stone in open surgery is dependent on the complex or simple stone According to the study of Nguyen Hong Truong (2007), the rate of residual stone was 34.6%; Tran Van Hinh was 47.22%; Huynh Van Nghia (2010) was 17% In order to limit the rate of residual stone, many domestic and foreign authors have studied and used many ways to open the renal pelvis of kidney parenchyma or use different supporting techniques to remove all stones and reduce the damage of parenchymal or vessel such as: x-ray application, ultrasound or endoscopic surgery, application of bio-glue The study results, although there are many incentives, but not meet the practical requirements The technique of flexible endoscopy has been applied in kidney stones since the beginning of the 21st century, has quickly proved many advantages in urinary calculi Renoendoscopy with a flexible scope assisted in open-surgery for complex kidney stones is a modern technique that has the advantage of allowing access to stones in kidneys without opening kidney parenchymal, thus reducing the rate residual stone and increasing the conservation of kidney Studies of this technical application are still in the early stages and not much In such circumstances, we carried out the study: "Evaluating the results of open pyelolithotomy with endoscopic support to treat multiple kidney stones" with objectives: To evaluate the results of open pyelolithotomy with endoscopic support to treat multiple kidney stones at Thanh Nhan Hospital To understand some factors related to the results of open pyelolithotomy with endoscopic support to treat multiple kidney stones at Thanh Nhan Hospital 2 New contributions of the thesis: The study was conducted in 55 patients with 56 kidneys, diagnosed multiple kidney stones, within years (32012 to 72017) at Thanh Nhan Hospital in Hanoi, patients were followed after surgery for month, months The study has analyzed and evaluated in detail the effectiveness, safety and preservation of renal parenchyma in surgery Research has shown the superiority of flexible endoscopy supporting open surgery to remove multiple kidney stones The thesis also analyzed and found some related factors affecting treatment results such as: age, shape of stone, position and number of stones, the angle between ureteropelvic axis and lower calyx axis … Renoendoscopy with flexible scope assisted in open surgery to treat multiple kidney stones is a modern technique with advantages, allowing to access to stones in calyx without opening the kidney parenchyma, thus reducing the rate of residual stone and increasing the conservation of kidney tissue Structure of the thesis: The thesis consists of 120 pages (Introduction pages, Overview 30 pages, Subjects and methods 22 pages, Results 25 pages, Dicussion 39 pages, Conclusion pages), with 45 tables, graphs The thesis also used 120 references, 18 references in Vietnamsese and 102 references in English CHAPTER OVERVIEW 1.1 Surgical anatomy of kidney 1.1.1 Classification of stone: According to Rocco F., C (Calculi): describes the morphology, size and topography of the stone in five descriptive categories : - C1: simple pelvic stone - C2: pelvic stone with multiple small stone in calices 3 - C3 (borderline): simple pelvicaliceal stone (1 calyx), with or without small stones in other calices - C4: complex pelvicaliceal stone (2 calices), with or without small stones in other calyx - C5: complete staghorn calculi 1.2 Treatment of Kidney Stones 1.2.1 Extracorporeal ShockWave Lithotripsy Due to the less invasive and gentle of extracorporeal shockwave lithotripsy (ESWL), some authors have indicated ESWL to treat kidney stones ESWL treated 70-75% of patients, however, it had to be done in several phages with an average of 3-4 times, in addition to using other support methods 17-57% 1.2.2 Pure Percutaneous Nephrolithotomy and PCNL with ESWL Like ESWL, PCNL has also been applied to treat staghorn calculi, but it is not an easy technique Many authors are hesitant to make more tunnel into kidneys because they believe this will increase complications To reduce the damage that the standard PCNL technique causes, a smaller device called minimally invasive PCNL or mini-PCNL has been used to limit bleeding, kidney parenchymal injury and safer 1.2.3 Open surgery Open surgery is still necessary in the following cases: - Struvite stone causes hydronephrosis or infected hydronephrosis - Stone with abnormal urinary anatomy - Giant stone - Fail to PCNL and/or ESWL 1.3 Pyelolithotomy There have been many studies in the world as well as in the Vietnam about methods of treating kidney stones However, despite the introduction of any new therapies, they are all aimed at: 1remove all stones, restore normal urinary tract circulation; 2- resolve kidney infections, and 3- conserve or improve kidney function 4 Open pyelolithotomy is a technique of choice because: it is relatively simple, less bleeding, does not cause tissue damage, does not affect kidney function and morphology, and less complications 1.4 Researches in reducing residual stone in open surgery Surgery for complex kidney stones is difficult, the major concern of the surgeons is the residual stones after surgery, and then the bleeding during and after surgery Complicated kidney stones often come with many small stones in the kidneys, these small stones are easy to miss in surgery, especially when the kidney tissue is thick, the neck of calyx is narrow, surgery has a lot of bleeding The residual stones cause many complications such as urine leakage, urinary tract infections The measures to support the prevention of stones used in kidney stone surgery include: 1.4.1 Using intra-operative X-rays Using X-rays taken in surgery to define small stones that have been in use since the 1980s of the last century Currently, due to the development of the X-ray with C-arm, it is more effective to use this method because it not only indicates the focal area of the stones in the upper or middle calyx, but when the arm rotation can indicate the front or back sides of the kidney 1.4.2 Using intra-operative ultrasound Schlegel J.U (1961) used ultrasound during process of operation to find small stones in calices Similarly, Sigel et al (1982) used ultrasound in surgery to find small stones in calices; and by ultrasound, the incision through the parenchymal entered directly stones According to the authors, stone-free was 15/16 patients 1.4.3 Intra-operative reno-endoscopy In 1964 Victor F Marsall used a flexible endoscope to visualize the ureters and renal pelvis In 1980, Zingg E.J and CS used a rigid endoscope in the operation of staghorn calculi, detected over 60% of small stones in calices in which they would remain in the kidney after surgery Then Terris M.K in the open surgery for staghorn calculi has been used flexible or rigid scope, even cystoscope to check, locate and remove some small caliceal stones In 2004 Unsal A used a pneumatic energy passing the incision of the pelvis to frag caliceal stones after removing the pelvic stone Traxel O and CS (2008) used flexible scope and laser energy to find and frag small stones in the kidney 1.5 The results of applying the flexible scope and laser energy in the treatment of kidney stone The application of flexible endoscopy to handle small stones scattered in calices in the treatment of multiple kidney stones are of particular interest to domestic and foreign authors The authors believe that all case need for active treatment, remove all stones as soon as possible, resolve for kidney infections, need to intervene before chronic renal pelvio-nephritis is too severe due to infection According to Ono Y et al., the factors related to residual stone: number and shape of stone (staghorn calculi combined with multiple stone, stones scattered in many calices), shape of the pelvis and calices pelvis (small pelvis with caliceal neck stenosis and dilated calices), thick parenchyma and surgical techniques are also factors that affect the rate of remnant stones Therefore, many less invasive techniques are implemented and bring very positive and encouraging results such as: not to incise renal tissue and conserving kidneys, passing postoperative period easily, shortened hospital stay However, each technique has its advantages and disadvantages 1.5.1 Laparoscopic lithotomy combined with flexible scope Initially, post- or transperitoneal laparoscopic surgery is indicated for simple upper ureteral stones, or pelvic stone which is outside the renal hilum Thanks to the development and improvement of the flexible scope, the surgeons have treated the stones deep in the kidneys, the stones in the renal calices, which had previously been removed with incision of renal parenchyma In Ramakumar's et al report, the rate of stone-free in three months in 19 patients underwent laparoscopic surgery and flexible endoscopic surgery is 90% Similar results were reported recently by Srivastava et al., Wang X et al with stone-free rates of 75% and 80% 1.5.2 Retrograde ureterorenoscopy with flexible lithotripsy Before the introduction of flexible scope with small caliber, the role of retrograde ureteroscopy in the treatment of kidney stones was very limited, in which the rate of complications was high The progress of retrograde ureteroscopy technique with flexible scope has helped urologists to access the entire ureter and renal pelvis system, but the indicatin is still much debate 1.5.3 Percutaneous nephrolithotomy with flexible scope The improvement of flexible endoscopy helped many urologists in the treatment of kidney stone Its application in PCNL has brought many encouraging results PCNL has treated complex stone, however, the residual stone also affects the quality of treatment Recently, many authors in the world have actively used flexible endoscope to treat remnant stones in the time of operation and have good results 1.5.4 Open surgery combined with flexible endoscope Open surgery for staghorn calcili is difficult, a large stone often accompany with small fragments in calices, easy to miss in surgery especially when the kidney tissue is thick, caliceal neck stenosis, bleeding Characteristics of stone: scattered all groups of calices Surgery to preserve renal parenchyma is very concerned by the urologists, how to get all the stones in surgery and reduce the damage to kidney tissue, relieve the phenomenon of urinary obstruction If you leave small stones in surgery, there will be many complications such as urinary tract infection, urine leakage, stone recurrence… To overcome these factors, many authors used flexible scope in the same operation to remove all the remaining stones scattered in calices In 2006, Terris M.K has taken open surgery combined with flexible, rigid scope or even a cystoscopy to check, locate and take some small stones in the calices Traxel O et al (2008) used flexible scope and laser energy to frag small stones in the kidney Traxel O et al (2010) performed surgery for 17 patients of staghorn calculi on horseshoe kidneys flexible scope in combination with holmium laser from December 2004 to May 2009 for results 15/17 patients (88.2%) of stone-free, 02/17 patients (11.8%) with residual stone 1.5.5 Role of Holmium laser Holmium Laser's efficiency on stone fragment depends on the energy of the emitted pulse and the diameter of the optical wire, with the wire type 365µm and 550µm, while the 200µm wire has a better "drilling" effect Types of 365µm and 550µm will be easier to push up stone than 200µm conductors There is no need to use eye protection when fragment; for example, if the energy is below 15W, the surgeon's conjunctiva and cornea are damaged only when the distance of the laser head is less than 100mm from the eye Laser fiber type: Holmium Laser conductor has the following diameter: 200, 230, 272, 365, 550 and 1000 µm CHAPTER SUBJECT AND METHOD 2.1 Subject Including 55 patients diagnosed multiple kidney stones, underwent open pyelolithotomy in combination with flexible endoscopy in Thanh Nhan hospital, Hanoi from March 2012 to July 2017 There was patient who has been undergone bilateral kidney stones, in which each side of the kidney ensures the research criteria Therefore, there would be 56 surgeries performed in the study 8 2.1.1 Criteria of selection - Multiple kidney stones: pelvic and at least caliceal stones - Open pyelolithotomy - Using flexible intra-operatively to reveal and remove caliceal stones - Patients agree to voluntarily participate in the study - Sufficient records to conduct data analysis and statistics 2.1.2 Criteria of exclusion - Severe hydronephrosis, thin renal parenchymal - Open pyelotomy combined with parenchymal incision - Do not found caliceal stones with endoscopy 2.2 Sample size formula n= Z12−α / p (1 − p) d2 2.3 Research method Prospective longitudinal followup study The data were prepared according to the study design, collecting and analyzing the results based on the follow-up, describing the research index over the longitudinal follow-up time 2.4 Index of study 2.4.1 Clinical characteristics Age and sex; BMI index; systemic diseases 2.4.2 Para-clinical characteristics * Blood test: - Blood tests were done in Thanh Nhan hospital - Classification of renal failure according to KDIGO * Urine test - Total urine analysis - Urine culture and microbiology report * Ultrasound: to evaluate the pelviocaliceal dilation (4 grades) * Plain X-ray film (KUB), to evaluate: - Unilateral of bilateral kidney stones - Number of stones: monolithic stone of multiple stones 9 - Size of caliceal stones - Site of caliceal stones: Select only C3, C4, C5 stones into the study * Intravenous Urography (IVU), CT-Scan: assessing renal excretory function in kidney of stone and opposite site; kidney dilatation and thickness of kidney parenchyma; location of stone and caliceal anatomy 2.4.3 Process of open pyelolithotomy in combination with flexible endoscopy to remove caliceal stones 2.4.3.1 Indication of surgery: - Age: 18 year old or older; BMI < 30 - History of stone operation: unilateral or bilateral kidney stone - Stone characteristics: pelvic stone and at least caliceal stones + Pelvic stone: C3, C4, C5 according to Rocco’s classification + Size of caliceal stone: < 20 mm/stone + Pelvis shape: B2, B3 and B4 + Angle between ureteropelvic axis and lower calyx axis ≥ 30o * Anesthesia: general or epidural anesthesia * Patients positioning: lateral position on a flexed operation table 2.4.3.2 Technique operation Step 1: Pyelolithotomy - Flank incision, access the pelvis - Simple pyelotomy, or Gil-Vernet incision - Remove the pelvic stone Step 2: Flexible endoscopy - Karl Storz’s setup of laparoscopic surgery - Flexible scope 10Fr (Olympus CYF-4) - Instrument: 272µm laser fiber, triprong forcep, Dormia basket Technique: - Irrigate the pelvis and calices with NaCl 0.9%; total sutures the incision of pelvis with Vicryl 4/0, except a hole for scope passing by - Using flexible scope 10Fr, visualize: pelvis, upper calyx, middle calyx and lower calyx, respectively; seek and remove caliceal 10 stones with Dormia basket or triprong forcep In case of large stone not pass throung the caliceal neck, laser holmium was used to fragment stone The 272 µm fiber, energy was set at level: + ‘Soft’ stone: 1.2J, 10Hz frequency + ‘Hard’ stone: 1.4 – 1.6J, 12-14Hz frequency - Do the last check all the peviocaliceal system to avoid remnant - Remove the scope, place a JJ-stent into the ureter, close the pelvis completely with Vicryl 4/0 running or simple suture 2.4.3.3 Criteria for evaluating surgical result - Result of open pyelolithotomy - Classification postoperative results and related factors + Success and failure, related factors + Duration of endoscopic lithotripsy for each calyx + Hospital stay, time of remove JJ-stent + Evaluate the results at month and month after discharge 2.4.3.4 Evaluate the intra-operative complications * Intra-operative bleeding: severe, moderate, mild Seek the relation between the grade of bleeding and pelvis 2.4.3.5 Evaluate the post-operative complications * Color of urine * Bleeding 2.4.3.6 Evaluate the surgical results * At the time of discharge - Stone-free, residual stone - Residual stone: location, size, number; if stone ≤ 4mm, left to free naturally; if stone ≥ 10mm, applying ESWL * Evaluate at month after surgery: urinary ultrasoud, plain Xray (KUB), blood test (ure and creatinin) + Intra- and post-operative complications * Evaluate the additional therapy for residual stone * Evaluate at month after surgery: 11 - Good: stone-free at discharge, stone-free after ESWL for residual stone; kidney function improvement (for patient with kidney failure prior to surgery); no intra- or post-operative somplications - Moderate: fragment stone < 5mm after ESWL for residual stone; sustentive kidney function (kidney failure prior to surgery) - Bad: residual stone but fail to ESWL; early stone formation (recurrence); increasing the level of kidney failure (kidney failure prior to surgery); infected hydronephrosis or giant hydronephrosis requiring to re-operate 2.5 Moral research - The research protocol was adopted by the Scientific Council of Military Medical Academy - Patients were thoroughly explained before taking part in the study and were completely voluntary with the attached application - The data and medical records were kept in compliance with the regulations of the Ministry of Health and the provisions of law 2.6 Data analysis - The data are managed and analyzed by SPSS 22.0 software CHAPTER RESULTS 3.1 Clinical and paraclinical characteristics related to surgery Table 3.1 Mean age 54 ± 12 (26 – 81) Graph 3.1 Male/female ratio 3/2 Table 3.2 Flank pain 94.6%; hematuria 1.8%; accidental stone 1.8% Table 3.3 Disease time: year 46 patients (83.6%), - year patients (14.5%), pt over year (1.8%) Table 3.4 Diabetes patients (12.7%), Hypertension pt (1.8%), History of pulmonary tuberculosis pt (1.8%) Table 3.5 History of stone surgery: 45 patients no history of intervention 81.8%, patients stone recurrence after surgery 5.5%; patients with ureteral stone in the same side 3.6%; patients with ureteral stone in the opposite side 5.5% 12 Table 3.6 Mean BMI index 54.5% Table 3.7 Preoperative ure and creatinin Table 3.8 Preoperative creatinin clearance Table 3.9 Evaluate the grade of kidney failure: 80% in normal range; patients stage of failure (7.3%); patients stage (10.9%), and pt stage (1.8%) Table 3.10 Urine culture positive in patients (5.4%) Graph 3.2 Hydronephrosis: 25% grade 1, 8.9% grade 2, and 3.6% grade Graph 3.3 Kidney stone: right 57.1%, left 42.9% Graph 3.4 Classification of kidney stone according to Rocco F: C3 32.1%, C4 51,8%, C5 16.1% Table 3.11 Stone location: middle-lower calices 42.9%, all calices 16.1% Table 3.12 There are 272 stones on 56 kidney, 4.9 stones each kidney on average Table 3.13 Stone size ≤ 10 mm (62.5%), 20 mm (37.5%) Table 3.14 Renal excretion: 52 kidneys in good 92.9%, kidney on moderate 7.1% Table 3.15 Stones: B2 26.8%, B3 16.1%, B4 57.1% Table 3.16 Angle between ureteropelvic axis and lower calyx axis: patients ≤ 450 (13.2%), 33 patients ≥ 450 (86.8%) 3.2 Surgical results Table 3.17 Simple pyelolithotomy 19.6%; standard Gil-Vernet pyelotomy 53.6%; non-standard Gil-Vernet 26.8% Table 3.18 Pumped pelvis and calices, took out 96 stones/47 kidneys (83.9%) Table 3.19 51 operation in which flexible scope accessed all calices 91.1%; operations the scope could not accessed lower calyx Table 3.20 Treated caliceal neck stenosis successfully with dilatation in cases (7.1%), unsuccessful in cases (3.6%) 13 Table 3.21 There were 157 stones: 35 stones in upper calyx (22.3%), 74 in middle (47.1%), and 48 in lower calyx (30.6%) Table 3.22 Stone removed with instruments: upper calyx 29.8%, middle calyx 55.3%, lower calyx 14.9% Stone fragment by laser: upper calyx 19.8%, middle calyx 43.8%, lower calyx 36.5% Table 3.23 Stones migrated from upper to lower calyx in patients (3.6%) Table 3.24 Time of laser lithotripsy: upper calyx 31 minutes, middle 33 – 40 mins, and lower calyx 39 – 50 mins, ≥ stones 80 mins Table 3.25 Relation between laser lithotripsy and number of stones: 63 minutes on average in 21 patients with – stones (37.5%); 69 minutes in 25 patients with stones (44.6%); 82 minutes in patients with stones (12.5%); 87 minutes in patients with more than caliceal stones (5.4%) Table 3.26 Reason of flexible renoendoscopy: pelvic rupture and caliceal neck injuries in patients (7.1%); the scope did not access to lower calyx in patients (5.4%) due to angle between ureteropelvic axis and lower calyx axis < 450; patients with caliceal neck stenosis so that the scope did not pass by 3.3 Analyze the relative factors Table 3.27 High success rate 94.3% in patients with stone ≤ 10 mm, differred from patients with stones 11 – 20 mm statistically significant Table 3.28 The relation between number of stones and was significantly different with p 10 mm (Table 3.27) The results showed a higher failure rate in the group with size > 10mm (p < 0.05) 4.2.3 Number of stone When dividing the group of stones by kidney into groups, group ≤ stones and group ≥ stones (Table 3.28), we found that the failure rate was higher in the group of or more stones (33.3%) compared to the group with ≤ stones (9.8%) 22 Flexible endoscopy used in kidney stone surgery is a difficult technique, if not said it is very difficult Therefore, if the more number of stones, the more difficult to control the entire pelviocaliceal system The risk of bleeding and residual stone will also be higher 4.2.4 Location of stone Studying the relationship between stone position and success rate, failure of flexible endoscopy, we found that the stone of lower calyx was significantly related to the failure rate of the technique Table 3.29 showed us that cases of failure in the study had cases of stones in the lower calyx It may be either alone or in combination with the remaining calices The success rate in the group of patients with stone in lower calyx accounted for only 81.6% 4.2.5 Angle between ureteropelvic axis and lower calyx axis The angle between ureteropelvic axis and lower calyx axis has been studied by many authors in the world, especially in ESWL, the authors believe that the anatomical characteristics of lower calyx and renal pelvis contribute an important part in the elimination and clearance of stones In our study, although open surgery in combination with flexible endoscopy to get the remaining stones in calices, there were many difficulties, common causes due to the small, acute angle between ureteropelvic axis and lower calyx axis, so the probe could not be passed through the caliceal neck We chosed 45 for this angle according to Resorlu et al (2012) (Table 3.30) 4.2.6 Approach stone In the study, the caliceal stone were immediately accessed and completely removed in 47 cases; patients accessed the stones but only partially managed the remnants; patients accounted for 8.9% the stones could not be accessed There were patients who had caliceal neck stenosis, much edema due to long-term stone occupied, accounted for 10.7% (Table 3.20), we had to carry out the dilatation with the tip of the probe into the calyx to access the stones Also in this study, caliceal neck of cases were completely stricture, unable to put the scope through, accounted for 3.6% 23 4.4 Postoperative results 4.4.1 Evaluate the results at the time of discharge The patients were examined at the 7th day or 10th day after surgery Table 3.34 showed the evaluation of the residual stone; there were 40 patients with complete stone-free (71.4%); 16 patients with residual stones (28.6%) The position and size of residual stones are shown in Table 3.35 and 3.36 4.4.2 Hospital stay The patient had the shortest post-operative hospital stay of days, the longest was 35 days The hospital stay was an average of 11.4 days Unsal’s report had an average hospital stay of 4.2 days (3 – days) 4.4.3 Results after months There were 13/16 patients with residual stones treated by ESWL at month after surgery The results were shown in Table 3.40: + Stone-free: patients, accounted for 23.1% + Remnant fragment < 5mm: patients, accounted for 53.8% + Stones were not broken: patients, accounted for 23.1% CONCLUSION Evaluate results of open pyelolithotomy with endoscopy assisted in the treatment of multiple kidney stones - The flexible endoscopy were performed on 56 patients, in which laser lithotripsy was completely successed on 47 patients (83.9%), failed to fragment stone in patients (5.6%), and stones could not be accessed in patients (10.7%) - Pumped pelvis and calices, took out 96 stones on 47 kidneys (83.9%) - There were 157 stones: 35 stones in upper calyx (22.3%), 74 in middle (47.1%), and 48 in lower calyx (30.6%) + With instruments, we took out 47/157 stones (29.9%) + Holmium laser lithotripsy in 96/110 stones (61.1%) - Intraoperative complications: rupture of peritoneum 1.8%, rupture of pleura 1.8% Postoperative complication: wound infection 3.6% 24 - Stone-free 71.4%; there were 32 residual stones in 16 kidneys - Results at month after surgery: + The stone was spontaneous passage after JJ-stent removed in patients, although no sign of sign on KUB and ultrasoud (18.8%) + ESWL for 13 patients with residual stones: stone-free in patients (23.1%), remnant fragment < 5mm in patients (53.8%), but stones were not broken in patients (23.1%) - - Results at month after surgery: good 46 patients (82.2%), medium patients (12.5%), and bad patients (5.3%) Understand factors related to the results of open pyelolithotomy with endoscopic support to treat multiple kidney stones - The preoperative assessment of pelvic stone and removing intact, without tearing the renal pelvis or damage to the caliceal neck, also determined the success of the surgery The study founded 15 cases of stones in the group (B2) with the rate of 26.8%, of which there were cases (7.1%) of rupture of renal pelvis and caliceal neck injuries - The stone size was a factor that is strongly related to postoperative stone-free rate The bigger the stone, the lower the rate of stone-free after surgery - The number of stones was also significant to surgical success We found that the failure rate was more common in the group of stones or more (33.3%) compared with the group with ≤ stones (9.8%) - The success rate of flexible endoscopy in cases with the acute angle between ureteropelvic axis and lower calyx axis was not high The success rate in the group of patients with stones in lower calyx accounted for only 81.6% - Assessing stones and managing remnants in calices was also a problem because the stones were in the calices for a long time, causing inflammation or narrowing of the caliceal neck In the study, we encountered cases of caliceal neck stenosis, high mucosal 25 edema, accounted for 10.7% We treated successfully with dilatation in cases (7.1%), unsuccessful in cases (3.6%)  ... fragment depends on the energy of the emitted pulse and the diameter of the optical wire, with the wire type 365µm and 550µm, while the 200µm wire has a better "drilling" effect Types of 365µm and... in the treatment of kidney stone The application of flexible endoscopy to handle small stones scattered in calices in the treatment of multiple kidney stones are of particular interest to domestic... residual stone: number and shape of stone (staghorn calculi combined with multiple stone, stones scattered in many calices), shape of the pelvis and calices pelvis (small pelvis with caliceal neck