Initial report of microperc in the treatment of pediatric nephrolithiasis

Ultrasound-guided mini-percutaneous nephrolithotomy in the treatment of upper urinary tract stones in children: A single-center evaluation

To evaluate the safety and efficacy of ultrasound-guided mini-percutaneous nephrolithotomy (mini-perc) for the treatment of upper urinary tract stones in children. We reviewed the records of 70 children with upper urinary tract stones who were treated with a mini-perc technique between July 2015 and April 2020. All puncture site selections and tract dilations were determined by Doppler ultrasonography. Patient age, height, weight, stone size, operation time, stone-free rate (SFR), postoperative complications, tubeless rate, and length of hospital stay (LOS) were recorded. Stone components were analysed using infrared spectroscopy. A total of 47 boys and 23 girls were included. Median weight and height of the patients were 18.5 kg and 110 cm, respectively. Median stone diameter was 2.0 cm. Median time to establish access was 4.0 min and median operation time was 25 min. Patients had median preoperative and postoperative haemoglobin levels of 121 and 113.5 g/L, median haemoglobin levels dropped to 8.0 g/L the day after surgery. No patient needed a blood transfusion. Eight children (11.4%) developed significant complications, including four cases with Clavien Grade I, one with Clavien Grade II, and three with Clavien Grade Ⅲ complications. One-day and 1-month follow-ups revealed a complete SFR of 95.7% (67/70) and 97.1% (68/70), respectively. Fifty-six patients (80.0%) did not require catheters of any type (total tubeless). Median LOS was 2.0 days. Ultrasound-guided mini-perc is safe and effective. The mini-perc technique is a feasible alternative for paediatric stone disease that does not result in major complications.

Comparison of super-mini versus mini percutaneous nephrolithotomy for the treatment of upper urinary tract stones in children: a single centre experience

PURPOSE

The efficacy and safety of super-mini percutaneous nephrolithotomy (SMP, 14 Fr) was compared with mini percutaneous nephrolithotomy (MPCNL, 16 Fr) for the treatment of upper urinary tract stones in children (< 14 years old).

METHODS

Clinical data of 133 paediatric patients with upper urinary tract stones treated with SMP or MPCNL between May 2012 and May 2019 were retrospectively analysed. The patients were divided into the SMP and MPCNL groups. Age, height, weight, stone size, operation time, stone-free rate (SFR), postoperative complications, tubeless rate, and length of postoperative hospital stay (LOS) were compared.

RESULTS

There were 66 patients (49.6%) in the SMP and 67 patients (50.4%) in the MPCNL group. No significant difference in the median age, weight, height and operation time, and SFR existed between the patients of the two groups. Larger stones were removed via SMP compared to those removed with MPCNL (2.0 vs. 1.5 cm, P = 0.001). LOS for SMP patients was significantly lower than that for the MPCNL patients (2 and 6 days, respectively, P < 0.0001). The tubeless rate for SMP was significantly higher than that for MPCNL (100% vs. 0%, P < 0.0001). Total complication rate of MPCNL was significantly higher than that of SMP (25.3% vs. 7.5%, P = 0.006). No patient required blood transfusion, and septicaemia, and other serious complications did not occur.

CONCLUSION

SMP is more effective than MPCNL for treating middle-sized upper urinary tract stones in children, and is associated with a shorter LOS and a higher tubeless rate.

Microperc with Self-Assembled Fr 4.85 Visual Needle and Ureteral Access Sheath

BACKGROUND

Micropercutaneous nephrolithotomy (microperc) is the least invasive among percutaneous nephrolithotripsy (PCNL) procedures. Although microperc has a high stone-free rate and certain advantages over other methods, modifications may be needed to improve the technique. We describe our experience performing microperc using a self-assembled visual needle and ureteral access sheath (UAS).

METHODS

Between June 2016 and April 2019, the data of 30 patients with kidney stones undergoing microperc with our self-assembled 4.8 Fr visual needle combined with a UAS was retrospectively analyzed. Patients were placed in an obilique spine lithotomy position.

RESULTS

Two cases were excluded: one due to conversion to mini PCNL and the other required flexible ureteroscopy during microperc. The remaining 28 cases included 18 men and 10 women, age 38.4 ± 7.5 years, stone size 1.7 ± 0.4 cm, and stone density on CT 969 ± 233 HU. Operative time was 47 ± 9.9 minutes, visual analogue scale score of tract pain on postoperative day 1 was 2.5 ± 1.0, hemoglobin decrease was 6.4 ± 1.0 g/L, and hospital stay was 3.1 ± 0.8 days. There was 1 case of fever and urinary infection, 2 cases of hematuria, and 1 case of flank pain. All symptoms resolved after conservative or antibiotic treatment. On postoperative day 1, 12 (42.9%) caseswere stone-free. The stone-free rates at postoperative month 1 and 3 were 92.9% (26/28) and 100% (28/28), respectively.

CONCLUSIONS

Our self-assembled visual needle and UAS instrument is effective for microperc. Use of the UAS may improve the operative outcome.

Outcomes of Ureteroscopy vs Mini-Percutaneous Nephrolithotomy for Pediatric Upper Urinary Tract Calculi: Comparative Nonrandomized Outcomes from Two Tertiary Endourology Referral Centers

Introduction: Pediatric upper urinary tract calculi can be treated by ureteroscopy (URS) or mini-percutaneous nephrolithotomy (mPCNL). We wanted to compare outcomes of URS and mPCNL from two tertiary referral centers that specialized in one of these treatments for pediatric stone disease. Materials and Methods: Data were collected from two tertiary centers for a 10-year period (2010-2019); one center specializing in URS and the other in mPCNL for consecutive patients ≤16 years undergoing either of these minimally invasive interventions. Upper urinary tract stones included stones in the kidney, pelviureteral junction, and proximal ureter, whereas mid or distal ureteral stones were excluded. Data were collected on patient and stone demographics. Outcomes of interest included stone-free rate (SFR) and complication rates. Results: During the study period, 55 patients underwent URS (group 1) and 40 patients underwent mPCNL (group 2). The mean stone size for groups 1 and 2 were 11.4 and 14.5 mm, respectively, whereas twice as many patients in group 1 had multiple stones. The final SFR and complication rates for groups 1 and 2 were 100% and 97.5%, and 5.4% and 12.5%, respectively. Although there were two Clavien II and one Clavien IV complication in the URS group, all five complications in mPCNL group were Clavien I. Conclusions: Our study shows excellent outcomes for upper urinary tract stones with both URS and mPCNL. Although treatment choices should be tailored to patients, each modality carries different advantages and our results reflect that high-volume centers specializing in a particular technique offer best outcomes, and this must also be borne in mind when counseling patients.

Treatment of renal calculi without hydronephrosis using a standard channel assisted by a visual puncture system

Objective

To study the safety and efficacy of standard channel establishment using a visual puncture system in the treatment of renal calculi without hydronephrosis.

Methods

We retrospectively analyzed data from 46 patients undergoing percutaneous nephrolithotomy via a standard channel assisted by a visual puncture system, including number of punctures, duration of procedure, hemoglobin level after surgery, calculi clearance rate, and postoperative complications.

Results

Sixty-nine channels were established, including a single channel in 26 cases, double channel in 17 cases, and three channels in 3 cases. The mean number of punctures was 1.50, mean time to establish the standard channel was 2.6 minutes, and duration of surgery was 31.3 minutes. No significant change in hemoglobin was observed after surgery. Forty-three patients had no residual calculi and three had small residual calculi on the day after surgery, representing a first-phase clearance rate of 93.48% (43/46). No significant complications were observed.

Conclusions

Hemorrhage during operation can be significantly reduced by establishing a standard channel using a visual puncture system. Moreover, the number of standard channels can be reduced and the incidence of complications lowered using this approach, which should be adopted widely for the treatment of renal calculi without hydronephrosis.

Comparing micropercutaneous nephrolithotomy and retrograde intrarenal surgery in treating 1-2 cm solitary renal stones in pediatric patients younger than 3 years

INTRODUCTION

To compare the effects of micropercutaneous nephrolithotomy (micro-PCNL) and retrograde intrarenal surgery (RIRS) in treating 1-2 cm solitary renal stones in pediatric patients aged less than 3 years.

PATIENTS AND METHODS

A retrospective analysis was performed on data from 57 children younger than 3 years who received micro-PCNL and RIRS surgery in the authors hospital from October 2016 to August 2018. The patients were divided into group 1, the micro-PCNL group, and group 2, the RIRS group. Peri-operative data including surgical time, number of anesthesia sessions, stone-free rate (SFR), and complications were analyzed.

RESULTS

There were 27 patients in group 1 and 30 patients in group 2, and the patients' mean ages were 19 ± 9.9 months and 21 ± 7.8 months, respectively (P = 0.462). The stone size was 1.6 ± 0.3 cm in group 1 and 1.7 ± 0.2 cm in group 2 (P = 0.217); the mean surgical time was 52 ± 7 min in group 1 and 48 ± 9 min in group 2 (P = 0.163), and the mean lithotripsy time was 21 ± 4 min in group 1 and 23 ± 5 min in group 2 (P = 0.148); and the SFR at 1 month after surgery was 88.9% in group 1 and 86.7% in group 2 (P = 0.799). The number of anesthesia sessions for patients was 1.4 ± 0.5 in group 1 and 2.7 ± 0.5 in group 2 (P < 0.001). The complication rate was 14.8% and 16.7% in group 1 and group 2, respectively (P = 0.714). None of the patients needed conversion to the 12-14 F mini-PCNL.

CONCLUSIONS

The results of this study showed that the surgical effects and complications from micro-PCNL and RIRS in treating young children with 1-2 cm solitary renal stones were similar. However, micro-PCNL reduced the need to prestent before surgery and allowed lower anesthesia sessions. Therefore, micro-PCNL is an effective alternative method for 1-2 cm solitary renal stones in patients below 3 years of age.

Pediatric Stone Disease

Once considered rare, pediatric nephrolithiasis has become a critical field of study in the last decade due to the rapid increase in incidence. Understanding the changing epidemiology and lifelong implications of pediatric stone disease is critically important to effectively manage the individual patient as well as identify risk factors for childhood onset that could be modified. Determining the role of diagnostic imaging in children is a unique challenge as limiting radiation and imaging stewardship should be priorities. Approaches to management have also changed, as technology continues to evolve and both medical and surgical options expand.

Clinical application of super-mini PCNL (SMP) in the treatment of upper urinary tract stones under ultrasound guidance

PURPOSE

To present the safety and efficacy of totally ultrasonography-guided Super-mini percutaneous nephrolithotomy (SMP) in the treatment of upper urinary tract stones both in children and adults.

PATIENTS AND METHODS

We carried out SMP in 104 patients (including 48 children and 56 adults) with upper urinary tract stones between June 2015 and February 2017. All steps of renal access were performed by ultrasonography. The lithotripsy was performed using either Holmium laser or pneumatic lithotripter. Perioperative and postoperative parameters along with operative data were recorded in detail.

RESULTS

The mean age of children and adult patients were 4.4 ± 3.6 and 44.3 ± 15.7 years old, respectively. The stone burden was comparable for both groups (1.72 ± 0.66 vs 1.74 ± 0.56 cm, p = 0.852). Mean operation time was not significant different between two groups (p = 0.052), while the mean haemoglobin drop in children was much lower in adult patients (6.3 ± 6.9 vs 10.9 ± 8.69, p = 0.004). Both groups had similar SFRs in postoperative 1 day and at 1-month follow-up (p = 1.000, p = 0.912). Mean hospital stay of children and adult patients was 2.3 ± 0.8 and 2.2 ± 0.76 days (p = 0.484). The total complication rate was significantly lower in two groups (p = 1.000); none of the patients required blood transfusion.

CONCLUSIONS

Ultrasonography-guided SMP was a safe and effective treatment option for moderate-sized upper urinary tract stones, and has the advantage of preventing radiation hazard, especially for pediatric stone patients.

Super-mini percutaneous nephrolithotomy for renal stone less than 25mm in pediatric patients: Could it be an alternative to shockwave lithotripsy?

AIM

To evaluate the efficacy of 2 different techniques: shock wave lithotripsy (SWL) vs. super-mini percutaneous nephrolithotomy (SMP), in terms of success as well as complication rates in pediatric renal stones sizing<25mm.

PATIENTS AND METHODS

A total of 219 children (aging between 1-17 years) undergoing 2 different treatment modalities (SWL vs. SMP) for kidney stones<25mm were included. Depending on the type of the procedure applied, children were divided into 2 different groups: group 1 (n=108), children treated with SWL, and group 2 (n=111), children treated with SMP. All treatment related parameters (stone free rates, number of sessions, treatment duration, hospitalization, presence of the residual fragments, complications as well as the need for additional interventions) were noted and evaluated between 2 groups in a comparative manner.

RESULTS

Evaluation of our data have clearly demonstrated that the percentage of residual fragments after SWL was significantly higher when compared with SMP. Although SWL required several sessions under general anesthesia in a certain per cent of the cases (54.6%), SMP was successful in one session in all of the cases. Last but not least, in addition to the similar minor complication rates observed in both group of cases, no major complication observed in any case and no case in both groups again required blood transfusion after these 2 procedures with no significant drop rates in hemoglobin levels.

CONCLUSIONS

Although SWL is still the preferred treatment modality for the majority of kidney stones in children due to its safe and non-invasive nature, SMP modality may be applied as a valuable alternative in this specific patient population for its excellent stone free rates obtained in a single session and acceptable complication rates in the minimal invasive management of stones<25mm.

Combined use of flexible ureteroscopic lithotripsy with micro-percutaneous nephrolithotomy in pediatric multiple kidney stones

BACKGROUND

We investigated the clinical value of treating pediatric multiple kidney stones with extensive distribution using flexible ureteroscopic lithotripsy (FUL) combined with micro-percutaneous nephrolithotomy (micro-PNL).

PATIENTS AND METHODS

In total, 21 pediatric patients with multiple renal calculi between May 2016 and June 2017 received FUL combined with micro-PNL. The group included 13 boys and eight girls; the patients' mean age was 3.8 years (range 1-8 years). The maximum stone diameter ranged from 1.0 to 1.5 cm. FUL was first performed in the lithotomy position to fragment stones that were located in the renal pelvis, and upper and mid-renal calyx. Patients were then moved to a prone position, and micro-PNL was performed to treat lower pole stones that could not be reached by the flexible ureteroscope during FUL. Percutaneous renal access to the lower calyx was achieved using a 4.8F "all-seeing needle" with ultrasound guidance, and stone fragmentation was performed with a 200-μm holmium laser at different settings to disintegrate 1- to 2-mm fragments.

RESULTS

All 21 pediatric patients with multiple kidney stones underwent combined FUL and micro-PNL. The stone free rate (SFR) was 85.7% (18/21). The mean surgical time was 45 min (range 30-70 min). The mean volume of irrigation fluid used was 480 mL (range 300-1200 mL). The mean surgical time for FUL and micro-PNL was 31 min and 14 min, respectively, and the mean volume of fluid used for FUL and micro-PNL was 360 mL and 120 mL, respectively. According to the modified Clavien classification, grade 1 and 2 postoperative complications occurred in five and one patients, respectively. The mean decrease in the level of hemoglobin was 0.4 g/dL (0-0.7 g/dL), and no patients required a transfusion. The average hospital stay was 3 days (range 2-5 days).

CONCLUSION

Combined FUL and micro-PNL is a safe, effective, and minimally invasive operation to remove multiple renal calculi with extensive distribution in children in selected cases.

Miniaturisation of PCNL

Conventional PCNL leads to a high stone-free rate but is associated with a significant treatment morbidity. To decrease the morbidity of PCNL but to achieve an equal stone-free rate, in 2001 a miniaturised version of a conventional PCNL (Mini-PCNL) was introduced. Meanwhile numerous modifications of the Mini-PCNL were reported. The ongoing experience with the Mini-PCNL technique showed that Mini-PCNL is not only a miniaturisation but also a different method to remove the stones, as the stones come out of the calyceal system only by means of the irrigation flow without any further need of forceps or baskets. Due to a limited number of papers in the literature, the guidelines so far do not distinguish between conventional and Mini-PCNL, although the Mini-PCNL already became a frequent treatment modality in daily routine worldwide. From the current point of view, Mini-PCNL can be recommended to treat all kinds of upper urinary tract stones exceeding a diameter of 10 mm. In this context, Mini-PCNL is a treatment alternative to flexible ureterorenoscopy, SWL and conventional PCNL. The available literature shows that the morbidity of Mini-PCNL is less and the stone-free rate is equal to that of conventional PCNL. It seems that there is no limitation to Mini-PCNL in the treatment of upper urinary tract stones. The future will show what kind of further miniaturisation of the Mini-PCNL procedure will be appropriate.

"Microperc" micropercutaneous nephrolithotomy: a review of the literature

Recent years have seen innovations in working armamentarium of percutaneous nephrolithotomy (PCNL) leading to development of novel modifications such as miniperc, ultra miniperc, and microperc. Amongst these microperc appears to be least invasive and various authors, off late, have reported their experience with the technique. Literature on microperc was reviewed by a MEDLINE/PubMed search with articles in the English language since 2011 in published peer-reviewed journals. Articles comprised of case series, comparative, and noncomparative studies. Different facets encompassing the technique were analyzed including contemporary indications, technique and its modifications, outcomes, and comparison with other modalities. Technique is reported to be associated with high success rate (82-100%) and short hospital stay (1-2 days). Studies have reported minimal hemoglobin drop (0.1-1.4 gm%) and fewer complications of lower Clavien grades. Going small in PCNL has gone a long way to present day 4.85F puncture system. Utilization of this novel modification is on rise with larger case series and comparative analysis being reported in past 2 years. Technique boasts of high clearance rate, lower morbidity and short hospital stay. In the present era, this innovation in percutaneous stone management appears to be another milestone in quest for "knife to cannula to needle to nothing".

A comparison of micro-PERC and retrograde intrarenal surgery results in pediatric patients with renal stones

INTRODUCTION

With advancements in endoscopic surgery, open surgical techniques for urinary system stones have paved the way for the application of less invasive treatment modalities in patients with pediatric kidney stone disease. These treatment options include extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), and retrograde intrarenal surgery (RIRS).

OBJECTIVE

We aimed to compare the efficacy and safety of RIRS and micro-PCNL techniques in the surgical treatment of kidney stones in pediatric patients.

STUDY DESIGN

A total of 48 pediatric patients, who underwent RIRS or micro-PERC for pediatric kidney stone disease, were retrospectively analyzed. Urinalysis, urine culture, serum creatinine (Cr), blood urea nitrogen (BUN), calcium, phosphorus, parathyroid hormone, 24-hour urine sample, complete blood count (CBC), urinary system X-ray, kidney ureter bladder (KUB), and urinary system ultrasonography (USG) test results were evaluated prior to the procedure. Intravenous pyelography (IVP), non-contrast computed tomography (CT), and renal scintigraphy evaluations were also performed, if necessary. The patients were divided into two groups: micro-PERC group (n = 25) and RIRS group (n = 23). Data relating to the duration of the operation, duration of fluoroscopy, length of hospitalization, complication rates, and stone-free rates were recorded.

RESULTS

The mean ages of the micro-PERC and RIRS groups were 4 ± 2.3 and 10.9 ± 3 years, respectively (p = 0.001). However, the mean stone sizes were 12.2 ± 2.8 and 13.7 ± 3.5 mm, respectively (p > 0.05). The mean duration of operation was 75.1 ± 18.9 min in the micro-PERC group and 62.3 ± 15.3 min in the RIRS group (p > 0.05). In addition, the mean duration of fluoroscopy was 115 ± 35.4 s in the micro-PERC group and 39.9 ± 15.3 s in the RIRS group. The stone-free rates in the micro-PERC and RIRS groups following the procedure were reported to be 84% (21/25) and 82.6% (19/23), respectively (p > 0.05). In terms of the degree of preoperative hydronephrosis between the groups, the rates of mild and moderate-severe disease were 76% (19 out of 25) and 24% (6 out of 25), and 69.5% (16 out of 23) and 30.4% (7 out of 23) in the micro-PERC and RIRS groups, respectively.

CONCLUSION

In recent years, technological developments in minimally invasive procedures, such as micro-PERC and RIRS, have facilitated choices made by urologists in the effective and safe first-line treatment in pediatric patients.

Small-calibre percutaneous nephrolithotomy (SC-PCNL). Therapeutic decision algorithm

INTRODUCTION

The progressive reduction in the calibre of the tract in percutaneous kidney surgery to the point of miniaturisation has expanded its use to smaller stones that until now have been treated with extracorporeal shock wave lithotripsy (ESWL) and retrograde intrarenal surgery (RIRS).

OBJECTIVE

To provide an update on the various techniques of small-calibre nephrolithotomy (SC-PCNL) analyse their efficacy, safety and indications and determine their degree of implantation at this time.

MATERIAL AND METHODS

We performed a review in PubMed of Spanish and English medical literature on the various techniques of SC-PCNL.

RESULTS

The use of SC-PCNL has reduced the morbidity associated with standard PCNL, particularly bleeding, and has enabled tubeless nephrolithotomy with greater safety. There are various techniques with blurred terminology (Miniperc, Microperc, Mini-microperc, Ultraminiperc), which differ in terms of gauge employed and in certain technical aspects that require their indications be specified. Currently, SC-PCNL competes with techniques that are less invasive than standard PCNL such as ESWL and the RIRS in treating small stones, but the role of SC-PCNL is still not sufficiently understood and continues to be the subject of debate.

CONCLUSIONS

The indications for PCNL are expanding to small stone sizes due to the miniaturisation of the technique. PCNL competes in this field with ESWL and RIRS. Larder studies are needed to establish the specific indications for PCNL in treating nephrolithiasis.

Retrograde intrarenal surgery and micro-percutaneous nephrolithotomy for renal lithiasis smaller than 2 CM

INTRODUCTION

Microperc is the upgraded form of percutaneous nephrolithotomy miniaturization. The aim of this study is to compare prospectively microperc and retrograde intrarenal surgery for the treatment of renal stones smaller than 2 cm.

MATERIAL AND METHODS

A comparative prospective study of both techniques was carried out between January 2014 and June 2015. Thirty-five patients were divided in two groups: Group A, 17 patients treated by retrograde intrarenal surgery and Group B, 18 patients treated by microperc. Stone clearance was assessed using CT scan 3 months after surgery.

RESULTS

Both groups were statistically comparable as demographic variables and stone size was similar (16.76 mm Group A vs 15.72 mm Group B). Success rate, hospital stay and JJ stenting were similar for both groups. There was no statistically significant difference regarding post-operatory complications: 17.64% Group A vs 5.56% Group B (p=0,062), all of them Clavien I and II. Surgical time was statistically different (63.82 min Group A vs 103.24 min Group B) as well as hemoglobin drop (0.62 g/dl Group A and 1.89 g/dl Group B).

CONCLUSION

Microperc is an effective and safe procedure for the treatment of renal lithiasis smaller than 2 cm, which makes it a good alternative to retrograde intrarenal surgery for this stone size. However, more prospective studies that include a larger cohort are necessary to confirm our results.

Percutaneous endoscopic treatment for urinary stones in pediatric patients: where we are now

BACKGROUND

Percutaneous nephrolithotomy (PCNL) has been adopted for pyelo-calyceal stones treatment in pediatric patients, starting from the 90's. Very recently, miniaturization of endoscopic instruments allowed less invasive procedures with low complication rate. We reviewed our experience on upper tract stone treatment utilizing two different percutaneous accesses, focusing on the recent new miniaturized devices offered for pediatric renal stones.

METHODS

Patients presenting upper tract urinary stones observed from January 2011 to December 2015 and treated by percutaneous renal access were prospectively evaluated: age, sex, metabolic issues, associated abnormalities, treatment modalities, hospital stay and complication rate were recorded in a specific database. Two different endourological percutaneous modalities were adopted, depending to the stone size and position. PCNL was performed through a direct calyceal puncture under ultrasonographic and fluoroscopic guidance and Amplatz access dilatation till 24 Fr. Ballistic energy was used for fragmentation. Micropercutaneous (Microperc) procedure was recently offered utilizing a 4.85 Fr metallic needle and Holmium:YAG laser lithotripsy under direct vision through a 0.9 mm high resolution optic flexible wire connected with a telescope.

RESULTS

Thirty-eight percutaneous access to pyelo-calyceal renal stones were performed on a total of 108 children treated for upper tract stones, aged 4 to 18 years (mean age 7.5 years). The overall number of procedures was 144 (36 repeated procedures). Cystinuria was diagnosed in 5 patients. PCNL was adopted in 28 patients, Microperc was utilized in 8 patients. Hemoglobin dropdown was limited to 1.20±0.80 mg% in PCNL and was not significant in Microperc. No blood transfusion was needed. No significant complications were observed. Stone free rate or minimal not significant residuals were achieved in 82% of PCNL and in 87.5% of Microperc, after a single procedure.

CONCLUSIONS

Percutaneous endoscopic treatment of renal calculi is feasible in pediatric age, with high success rate in a single step. Advanced miniaturized endoscopic devices as Microperc guarantee high efficacy and reduced complication rate, but endo-urological experience and adequate learning curve are required, especially in small body weight children. Centralization of these patients in Pediatric Stone Centers is welcomed to optimize results and reduce risks.

Comparison of Retrograde Intrarenal Surgery and Micro-Percutaneous Nephrolithotomy in Moderately Sized Pediatric Kidney Stones

PURPOSE

To compare the effectiveness and reliability of retrograde intrarenal surgery (RIRS) and micro-percutaneous nephrolithotomy (micro-perc) for the management of kidney stones in pediatric patients.

MATERIALS AND METHODS

A retrospective analysis was made of pediatric patients aged <18 years with kidney stones that ranged from 10 to 20 mm in size, who underwent RIRS (n = 36) or micro-perc (n = 45) in referral centers.

RESULTS

In the RIRS group, the mean age of patients was 8.39 ± 4.72 years and in the micro-perc group, it was 5.62 ± 4.50 years (p = 0.01). The mean stone size was 12.80 ± 3.03 mm in the RIRS group and 13.97 ± 3.46 mm in the micro-perc group (p = 0.189). The success rate was 86.2% (n = 31) in the RIRS group and 80.0% (n = 36) in the micro-perc group (p = 0.47). The mean complication rate was 16.6% and 13.3% in the RIRS and micro-perc groups, respectively (p = 0.675). Hospital stay and radiation exposure were significantly lower in the RIRS group (all p < 0.001). The mean anesthesia session was 1.94 in the RIRS group and 1.26 in the micro-perc group (p < 0.001). The mean hemoglobin drop was 0.53 ± 0.87 g/dL in the micro-perc group, and none of the cases required blood transfusion.

CONCLUSION

The results of this study suggested that micro-perc and RIRS were highly effective methods for the treatment of moderately sized renal stones in children, with comparable success and complication rates. Patients and their parents should be informed about the currently available treatment options, and of their efficacy and safety. However, further clinical trials are needed to support these results.

Micro-percutaneous nephrolithotomy in the treatment of pediatric nephrolithiasis: A single-center experience

OBJECTIVE

We aimed to clarify the applicability and safety of micro-PNL (microperc) in the treatment of pediatric kidney stones.

MATERIAL AND METHODS

A single center prospective trial was initiated, and microperc was performed in 40 children using the same two methods: the classical all-seeing needle and microsheath method. Stone fragmentation was performed using a 200-μm holmium:YAG laser fiber.

RESULTS

The mean age of the patients was 6.3±4.4years (range: 7months-16years). Fourteen were less than 3years old. The average calculous size was 16.5mm (range: 10-36mm). In 20 patients, access was achieved through the all-seeing needle method. In the other patients, access was achieved by the microsheath method. Conversion to mini-PNL was required in 2 patients due to intraoperative bleeding in one and a high stone burden in the other. The mean hospital stay was 3.8±1.2days (range: 1-10days), and the mean hemoglobin decrease was 0.7±0.3mg/dl (range: 0-1.7mg/dl).The duration of surgery and fluoroscopic screening was 75min and 3.7min, respectively. A DJ stent was placed in 11 patients due to a high stone burden. A ureteral stent was left for 1day in the rest of the cases. Complete clearance was achieved in the other 32 children. None of the patients required transfusion caused by renal hemorrhage. In 1 patient, extravasation of the irrigation fluid caused abdominal distention. As assessed by KUB and/or an ultrasound, the overall stone-free rate at 6weeks was 80%. There were residual fragments in 6 patients (15%).

CONCLUSIONS

Our results show that microperc is a safe and effective procedure for the treatment of pediatric kidney stones. Children with small renal calculi and with nonobstructed collecting systems are suitable for microperc.

Ultra-mini-percutaneous nephrolithotomy in pediatric nephrolithiasis: both low pressure and high efficiency

INTRODUCTION

The management of urolithiasis in children differs from adults because of anatomic and metabolic abnormalities. At present, various minimally invasive and invasive treatment strategies have been recommended to treat urinary tract Stones, including shock wave lithotripsy (SWL), standard percutaneous nephrolithotomy (PNL), mini-PNL, retrograde intrarenal surgery (RIRS), micro-PNL, and a new technique termed ultra-mini PNL (UMP). UMP is a new method for the treatment of kidney stones. The main difference between UMP and standard PNL or mini-PNL lies in the small access sheath and in its design. A 9.5F pediatric compact cystoscope was used (Figure). A major advantage of UMP is that it provides similar stone-free rates when compared with standard PNL, with lower intrarenal pressure than micro-PNL.

OBJECTIVE

The aim of the study was to determine the applicability and safety of UMP in the treatment of pediatric kidney stones.

PATIENTS AND METHODS

We retrospectively reviewed the files of 39 kidney stones in children who had undergone UMP between May 2011 and October 2014. The indications for UMP included stones resistant to SWL, stones requiring repeated sessions of SWL, and stones size larger than 20 mm.

RESULTS

The study included 17 females and 22 males, with a mean age of 5.8 ± 4.6 years. The mean hemoglobin loss was 0.9 ± 0.6 mg/dL and none of the patients required a blood transfusion. The complication rate of the PNL procedure was 15.3% (n = 6). Complete clearance was achieved in 32 patients (82%) with UMP monotherapy, which increased to 34% (87.1%) 4 weeks after the operation.

DISCUSSION

Management of urolithiasis necessitates a balance between stone clearance and morbidity related to the procedure. SWL often leads to persistent residual stones. The developing RIRS can minimize the risks associated with bleeding and visceral injury, but sometimes the abnormal pelvicaliceal anatomy and poor imaging of the flexible ureteroscopy may impact its success rate and applications. It has been reported that PNL can be performed safely and effectively to achieve a higher stone-free rate; however, it has serious complications such as bleeding that requires blood transfusion in 11-14% of the cases with increased risk of kidney loss. The recent development of smaller sheaths allows tract formation with minimal damage to the renal parenchyma, thereby reducing procedure-related morbidity without diminishing its therapeutic efficacy.

CONCLUSION

The most important advantage of this surgical technique that has been developed is similar stone-free rates to standard PNL and lower intrarenal pressure than micro-PNL. Our experience supports that UMP is safe and effective for the management of renal stones in children.

Micropercutaneous nephrolithotripsy: initial experience

INTRODUCTION

For small renal calculi (< 2 cm) the currently available treatment options include extracorporeal shockwave lithotripsy (ESWL), retrograde intrarenal surgery (RIRS) and standard/mini percutaneous nephrolithotomy (PNL). A new method, microperc, has therefore been developed, in which a smaller tract size and smaller instruments were used.

AIM

To present our clinical experiences with micropercutaneous nephrolithotripsy (microperc) in the treatment of small renal calculi.

MATERIAL AND METHODS

We retrospectively evaluated patients with small renal calculi who underwent microperc between February and June 2013. A 4.8 Fr 'all-seeing needle' was used to achieve percutaneous renal access with the C-arm fluoroscopy guidance in the prone position. Holmium: YAG laser 272 µm fiber was used for stone fragmentation.

RESULTS

A total of 20 patients underwent the microperc procedure. The mean age of the patients was 46.5 ±13.8 years. The mean stone size was 13 ±3 mm. The stone-free rate (SFR) was 90% (18/20). Two patients had clinically significant residual fragments (≥ 4 mm). The mean operation and fluoroscopy times were 107.5 ±37 min and 45 ±40 s respectively. The mean postoperative drop in hemoglobin was 1.2 ±0.9 g/dl, and 1 patient required blood transfusion. The patients were discharged after an average hospitalization of 1.4 ±0.8 days. Two complications, urinary tract infection and blood loss requiring blood transfusion, were observed in 2 patients postoperatively.

CONCLUSIONS

We suggest that microperc should be considered for the treatment of small renal stones.

A Major Complication in Micropercutaneous Nephrolithotomy: Upper Calyceal Perforation with Extrarenal Migration of Stone Fragments due to Increased Intrarenal Pelvic Pressure

Micropercutaneous nephrolithotomy is a safe and efficient technique for appropriate sized stones. It is performed through a 4.85 Fr all-seeing needle and stones are fragmented into dust, without the need for tract dilatation, unlike other percutaneous nephrolithotomy types. Even though micropercutaneous nephrolithotomy has many advantages, increase in intrapelvic pressure during surgery may cause rare but serious complications. Herein we report a case of micropercutaneous nephrolithotomy in a 20-year-old woman with a 20 mm right renal pelvis stone and present an undesired outcome of this complication, upper calyceal perforation. Right lower calyceal access was performed with 4.85 Fr all-seeing needle and 2 cm renal pelvis stone was fragmented by 272 μm Holmium-Yag laser system. Upper calyceal perforation and infrahepatic accumulation of stone fragments were detected by fluoroscopy during the surgery. Postoperative imagings revealed perirenal urinoma, perirenal and infrahepatic stone fragments, and lower calyceal stone fragments inside the system. On second postoperative day, minipercutaneous nephrolithotomy and double J catheter insertion procedures were applied for effective drainage and stone clearance. Risk of calyceal perforation and urinoma formation, due to increased intrapelvic pressure during micropercutaneous nephrolithotomy, should be kept in mind.

A Comparison of 2 Percutaneous Nephrolithotomy Techniques for the Treatment of Pediatric Kidney Stones of Sizes 10-20 mm: Microperc vs Miniperc

OBJECTIVE

To compare outcomes of micro-percutaneous nephrolithotomy (PNL; microperc) with mini-PNL (miniperc) in the treatment of pediatric renal stones of sizes 10-20 mm.

MATERIALS AND METHODS

Patients aged <18 years who underwent PNL for renal stones of sizes 10-20 mm between August 2011 and March 2014 in 3 referral centers were reviewed retrospectively. Patients were evaluated in the following 2 groups: microperc (group 1) and miniperc (group 2). Demographics and perioperative parameters (fluoroscopy and operation time, hemoglobin drop, and stone-free and complication rates) were retrospectively analyzed.

RESULTS

A total of 119 patients were evaluated, including group 1 (n = 56) for microperc and group 2 (n = 63) for miniperc. We found mean stone sizes as 13.4 ± 3.4 and 14.8 ± 3.7 mm in the groups, respectively (P = .046). Mean operation and fluoroscopy times were 57.1 ± 31.2 minutes and 132.4 ± 92.5 seconds in the microperc group and 68.9 ± 36.7 minutes and 226.2 ± 166.2 seconds in the miniperc group, respectively (P = .110 and P <.001). Stone-free rates were similar in both groups (82.1% vs 87.3%; P = .433 and 92.8% vs 93.6%; P = 0673) on postoperative day 1 and at first-month follow-up. The mean hemoglobin drop in group 2 differed from that in group 1 significantly (P <.001). The difference of average hospitalization times was statistically significant (43.0 ± 15.4 vs 68.5 ± 31.7 hours; P <.001).

CONCLUSION

Our outcomes show that microperc may be preferred as an alternative to mini-PNL for the treatment of pediatric kidney stones of sizes 10-20 mm with comparable success and complication rates, as well as shorter hospitalization and fluoroscopy times.

Management of stone disease in infants

Evaluating and treating renal stone disease in infants are technically challenging. In this study, we evaluated the surgical treatment of renal stones in children under 1 year of age. We retrospectively reviewed the records of patients under 1 year old who were treated with ESWL, endourological or open surgical procedures for renal stone disease between January, 2009 and December, 2012. The patients' age, gender, stone size, stone location and number, complications, stone-free status, and postoperative complications were recorded. 19 of 121 infants with a mean age of 10.2 ± 3.07 months were treated with surgical procedures. Six (75%) of eight cystinuria patients required a surgical intervention. Retrograde endoscopic management was performed in thirteen patients (63.4%) as an initial surgical approach. There were three major (15.7%) complications. The rate of open surgical procedures was 31.6% (6 of 19 infants). The cutoff value of stone size for open surgery was 10 mm. There was a significant relationship between the conversion to open procedures and stone size, stone location, and symptom presentation especially the presence of obstruction (p < 0.05). After repeated treatments, the stone clearance rate of RIRS reached 84.6%. Retrograde intrarenal surgery is an effective and safe treatment method for renal stones in infants and can be used as a first-line therapy in most patients under 1 year old. This is especially important if an associated ureteral stone or lower pole stone that requires treatment is present and for patients with cystinuria, which does not respond favorably to ESWL.

Is Micropercutaneous Nephrolithotomy Technique Really Efficacicous for the Treatment of Moderate Size Renal Calculi? Yes

OBJECTIVE

To present our clinical experiences with micropercutaneous nephrolithotomy in the treatment of moderate-sized renal calculi from a single center.

METHODS

We retrospectively evaluated the patients with moderate-sized renal calculi who underwent micro-percutaneous nephrolithotomy between December 2012 and Septermber 2013.

RESULTS

A total of 68 patients and 70 renal units underwent microperc procedure. Mean age of patients was 41.4 ± 18.8. The mean stone size was 122 ± 83 mm(2). The operations were performed under spinal anesthesia in 89.7% of the patients. Stone-free rate was 95.7 % (67/70). Clinically significant residual fragments were observed in three patients. The average duration of operation and mean fluoroscopy time was 40 ± 23 min and 108 ± 72 s, respectively. The mean postoperative drop in hemoglobin was 0.95 ± 0.7 while no patient required blood transfusion. Patients were discharged after an average hospitalization time of 27.5 ± 12.4 h. A total of 4 complications (5.7%), including urinary tract infection (Clavien I) in one patient and renal colics requiring stent insertion (Clavien IIIa) in three patients, were observed postoperatively.

CONCLUSION

Microperc technique is safe, feasible, and efficacious. We suggest that micro-percutaneous nephrolithotomy should be considered for the treatment of moderate-sized renal stones as an alternative to SWL and RIRS failures and also may be considered even primarily.

Micropercutaneous nephrolithotomy. A new therapeutic option for pediatric renal lithiasis

INTRODUCTION

Micropercutaneous nephrolithotomy is an evolution from the conventional percutaneous surgery in which pyelocaliceal access is obtained through minimum bore holes. Its objective is the complete removal of the calculi, lowering the morbidity associated with larger bore percutaneous tracts.

MATERIAL AND METHODS

We present the case of a micropercutaneous nephrolithotomy performed in a 14-year-old female patient with a 35 mm diameter kidney stone located in the renal pelvis. Surgery was performed in the Galdakao-modified supine Valdivia position. Puncture was done under ultrasound and fluoroscopic guidance. The 4.85 Ch needle of the Microperc(®) set was used, completing the procedure through the 8 Ch working shaft. Lasertripsy was done with the Ho:YAG laser. An indwelling double J stent was placed at the end of the procedure.

RESULTS

Operating time was 170 minutes. Hospital stay was one day. She suffered renal colic after 72 hours, which was resolved with oral analgesic treatment at home (Clavien I). She returned to school on the fifth postoperative day. The double J was removed at 2 weeks. At one month of the surgery, the patient is asymptomatic, a 4mm lower calyx residual stone being observed in the abdominal ultrasound.

CONCLUSION

Micropercutaneous nephrolithotomy is a step forward towards the search for a less invasive kidney stone treatment. It is a safe and effective technique in the pediatric population, and it can be performed in the supine position, even in orthotropic kidneys. Future studies and collaborative works will help to better define its indications, to optimize its technique and to analyze its cost-effectiveness compared with other treatment options.

[PCNL: what's changed?]

PCNL is a endourological technique for the treatment of kidney stones disease. It's aim is to achieve the complete clearance via a percutaneous access. This technique, as we know it today, was developed by Johanson and Fernstrom in 1976 who used the technological advances in percutaneous fluoroscopy to get the percutaneous access. Following the application of various sources of energy for the fragmentation of the calculi such as ultrasound energy, there was the worldwide diffusion of PCNL thanks to Alken and Marbergen in Europe, Segura and Clayman in the USA. Despite in the early '80s the PCNL lost the initial impulse in favor of the SWL, in the '90s, it revived a second golden age through the application of emerging technologies such as computed tomography, techniques of obtaining the percutaneous access, flexible instrumentation, laser energy and, more recently, robotic surgery, and virtual reality. All of these contributed to bring the PCNL on the road up of the mini-invasiveness to the latest development of Microperc. The Microperc allows the treatment of stones of 2 cm in diameter also, obtaining the access under ultrasound, fluoroscopic and direct vision guidance. A complete system including micor-optics, laser fiber and irrigation system is then inserted into the same needle with a diameter of 4.85, 8 or 10 Fr The CROES used logistic developments by creating a global network and a multi-center database. The PCNL study, concluded in 2009, has led to the publication of as many as 27 scientific papers on this subject.