A prospective comparative study to evaluate safety and efficacy of pneumatic versus laser lithotripsy in mini-percutaneous nephrolithotomy

OBJECTIVE

The choice of lithotripter is an important part of planning in mini-percutaneous nephrolithotomy (mini perc) as the operating time is prolonged due to reduced sheath size and smaller working channel. Previous studies mostly reported the use of laser lithotripter for stone fragmentation while the literature on pneumatic lithotripter use in miniperc is scant.

METHODS

In this study, we compared the efficacy and safety of the laser lithotripter (LL) vs pneumatic lithotripter (PL) in miniperc for small to medium-sized renal/upper ureteric stones (size: 1-2 cm). All consecutive patients who underwent miniperc from September 2020 to August 2022 were included in the study. Laser lithotripter was used in 81 patients (group LL), while pneumatic was used in 75 patients (group PL). The preoperative, operative, and postoperative findings were compared.

RESULTS

Baseline patient characteristics (age, sex, body mass index, and co-morbid illness) and stone characteristics (size, stone number, laterality, presence of staghorn calculi, presence of hydronephrosis, Guy's stone scores) were comparable between the two groups (P>0.05). The mean operative time was comparable (P=0.38) while the mean fragmentation time was significantly higher in the PL group (35.42±6.34 vs 28.96±2.82 minutes; P<0.01). 29.3% required forceps/basket for stone removal in PL group as compared to 7.4% in LL group (P=0.02). Mean VAS (Visual Analog Scale) score on the first post-operative day, stone clearance, drop in hemoglobin, average hospital stay, stone clearance at 3 months postoperative, and complications were comparable (P>0.05).

CONCLUSION

Lithotripsy with pneumatic lithotripter can be used as an equally effective and safe alternative to laser lithotripter in mini-perc for treatment of small-medium sized renal/upper ureteric calculi.

Mini-Percutaneous Nephrolithotomy Outcomes in the Obese Population: A Retrospective Review

Introduction and Objectives: Mini-percutaneous nephrolithotomy (PCNL) has gained popularity over the last decade due to its stone-free rate comparable to traditional PCNL but with decreased risk of complications. While the data on mini-PCNL has been favorable thus far, no study today has evaluated outcomes in obese patients. Methods: All patients undergoing mini-PCNL at our institution since we began its use in 2019 were included in this study. Mini-PCNL was defined as access sheath ≤22F in size. An obese group with body mass index (BMI) ≥30 was compared to a nonobese group with BMI <30. A patient was considered relatively stone free if residual fragments were <4 mm on follow-up CT with ≤3 mm cuts. Fisher exact test was used to compare dichotomous differences between variables, and t-test to compare continuous variables. Results: We identified 67 patients who underwent mini-PCNL during the study period with 33 patients in the obese group. Median BMI in the obese group was 36.4 kg/m2 compared to 25.05 kg/m2 in nonobese. There were no blood transfusions in either group during the study period. There was no statistical difference between the obese vs nonobese group for age, access sheath size, change in hemoglobin, same day discharge, percent relatively stone free, emergency department visit within 30 days, and median largest single stone diameter. There was a significant difference in the sum of all treated stone diameter in the obese group (median 15 mm) vs nonobese (median 18 mm, p = 0.02) (Table 1). Conclusion: Mini-PCNL appears to be equally safe and effective in obese and nonobese patients alike. While there was a statistically significantly higher amount of overall stone burden in the nonobese groups, the overall difference is not clinically significant. Further research is needed to validate our experience.

Totally X-ray-Free Ultrasound-Guided Mini-Percutaneous Nephrolithotomy in Galdakao-Modified Supine Valdivia Position: A Novel Combined Surgery

We introduced a novel surgery that combines ultrasound guidance, miniaturization and Galdakao-modified supine Valdivia (GMSV) position in percutaneous nephrolithotomy (PCNL) and evaluated the safety and efficacy. This retrospective, single-center study retrospectively reviewed 150 patients who underwent ultrasound-guided mini-PCNL in the GMSV position from November 2019 to March 2022. All perioperative parameters were collected. Stone-free status was defined as no residual stones or clinically insignificant residual fragments (CIRF) <0.4 cm on postoperative day one. Among the 150 patients, the mean age was 56.96 years. The mean stone size was 3.19 cm (427 mm2). The mean S.T.O.N.E. score was 7.61, including 36 patients (24%) with scores ≥9. The mean operative time was 66.22 min, and the success rate of renal access creation in the first attempt was 88.7%. One hundred and forty (93.3%) patients were stone free. The mean decrease in Hemoglobin was 1.04 g/dL, and no patient needed a blood transfusion. Complications included transient hematuria (n = 13, 8.7%), bladder blood clot retention (n = 2, 1.3%), fever (n = 15, 10%) and sepsis (n = 2, 1.3%). Totally X-ray-free ultrasound-guided mini-PCNL in the GMSV position is feasible, safe and effective for patients with upper urinary tract stones, indicating the synergistic and complementary effects of the three novel techniques.

Definition and Unfavorable Risk Factors of Trifecta in Mini-Percutaneous Nephrolithotomy

Objectives: In performing mini-percutaneous nephrolithotomy (PCNL), we aimed at achieving the trifecta of stone-free status and no complications in a single treatment session. We analyzed our experience to determine negative predictors for achieving these three-fold goals. Patients and Methods: The data of all consecutive patients who underwent tubeless mini-PCNL between July 2015 and March 2020 in two hospitals were retrospectively reviewed. Stone-free was defined as no residual stones. Complications were recorded and graded according to modified Clavien classification. Patients were divided into two groups according to the outcome (trifecta and non-trifecta). Factors affecting the outcome were compared between both groups by using univariate and multivariate analyses to detect independent unfavorable risk factors. Results: The study included 944 patients with mean age 40.2 years (standard deviation: 13.6). The stone-free rate after one session of mini-PCNL was 90.7%. Auxiliary procedures were needed in 14 patients (1.5%). Complications were observed in 76 patients (8.1%). Trifecta was achieved in 792 patients (84%). Independent unfavorable risk factors in multivariate analysis were number of caliceal groups affected by the stones (relative risks were 1.95 to 2.27 and 5.7 for one, two, and three caliceal groups respectively) and number of percutaneous tracts (relative risk was 2.2). Stone size and complexity were not significant predictors of missing trifecta in multivariate analysis. Conclusions: Mini-PCNL can achieve a high rate of trifecta (84%) for different stone sizes and complexities. Stones distribution in multiple caliceal groups and multiple tracts are the independent unfavorable risk factor.

Role of Mini-Percutaneous Nephrolithotomy in the Management of Pediatric Stone Disease: A Systematic Review of Literature

Introduction: Kidney stone disease in the pediatric setting is rare, but the incidence is rising. Mini-percutaneous nephrolithotomy (mPCNL) is one of the newer surgical interventions to have been developed in recent decades. The aim of this study was to carry out a systematic review (SR) to formally evaluate the safety and efficacy of pediatric mPCNL, which was defined as PCNLs using tract size between 15F and 20F. Methods: An SR was carried out in accordance with Cochrane guidelines and A MeaSurement Tool to Assess systematic Reviews (AMSTAR) checklist. Original studies reporting on outcomes of mPCNL with 20 or more patients (aged ≤18 years) were included. Results: Eight studies were finally identified, which satisfied our predefined criteria. This included two randomized trials and six cohort studies. A total of 384 patients with a weighted mean age of 7.5 years (range: 0.5-18 years) and a male:female ratio of 3:2 underwent mPCNL. The weighted mean stone size was 1.2 cm (range: 0.8-3.5 cm). The weighted mean operative time and length of hospital stay were 76.8 minutes (range: 20-120 minutes) and 4.6 days (range: 1-33 days), respectively. The most common location(s) of stones were lower pole (57%) and renal pelvis (24.3%). The weighted mean initial and overall stone-free rates were 87.9% (range: 76%-97.5%) and 97% (range: 91.3%-100%), respectively. None of the cases required intraoperative conversion to standard PCNL. Complications occurred in 19% (n = 73) of patients. The weighted mean transfusion rate reported across studies was 3.3% (range: 0%-10.3%). Conclusions: mPCNL is safe and effective in the pediatric population. Further randomized studies will help determine its formal role in pediatric endourology and help guideline recommendations accordingly.

Three-dimensionally printed non-biological simulator for percutaneous nephrolithotomy training

Objective: We sought to improve the educational and pre-operative training on various stages of percutaneous nephrolithotomy (PCNL) under fluoroscopic and ultrasound guidance. We developed a three-dimensional (3D) printed simulator (3D-printed PCNL model) for urological trainees.Methods: 40 s year urology residents were randomly assigned into two groups, completing PCNL surgical steps on a URO Mentor™ surgical simulator (Group A) or on our new 3D-printed PCNL model (Group B). Following the training, both groups completed a standardized questionnaire (Likert scale from 0 to 10) which we used to asses the learning curve associated with PCNL training.Results: The mean score of Group A was 65.2/80 while Group B was 76.1/80. Mann-Whitney U-test showed no significant difference between the groups (U = 16, p < 0.05).Conclusion: The 3D-printed PCNL model developed is a novel and highly effective tool that can facilitate enhanced endourological education and personalized pre-operative planning for urolithiasis cases. According to the criteria tested, residents who used our 3D-printed PCNL models performed better under all metrics.

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.

Mini PCNL Over Standard PCNL: What Makes it Better?

The incidence of small- and medium-size renal stones is rising. Stone clearance, bleeding, urine leak, and infectious complications are major concerns for urologists. They can choose the best technique from a list of armamentarium available. Minimally invasive approach like percutaneous nephrolithotomy (PCNL) has significantly influenced renal stone management since 1976. Miniaturization of the instruments innovate more effective and safer alternatives for urolithasis management. The outcome of mini-PCNL is explored and compared with standard PCNL in this review. Original research articles were reviewed using a systematic approach (keyword electronic database search). Duplicates were excluded in each step and 19 original articles out of 156 hits were analyzed. Mini-PCNL has significantly less bleeding complications and hospital stay. There were no significant difference in stone free rate between mini-PCNL and standard PCNL. The stone-free rate and complications rates were less dependent on the technique of puncture, tract dilatation, and energy used to fragment stones. The total operative time became slightly longer in mini-PCNL attributed to the sheath size and stone fragments retrieval. We found that mini-PCNL is as effective as standard PCNL with fewer complications. Stone burden is the key factor responsible for overall stone-free rate. However, the recommendation is limited by quality of study and the sample sizes.

Mini PCNL for renal calculi: does size matter?

OBJECTIVE

To evaluate the minimally invasive percutaneous nephrolithotomy (MIP) system for renal calculi.

PATIENTS AND METHODS

Consecutive patients undergoing mini-percutaneous nephrolithotomy (mPCNL) procedures with the MIP system were enrolled. Patient position, American Society of Anesthesiologists classification, puncture location, stone clearance, postoperative drainage and complications were recorded, and features unique to MIP were noted.

RESULTS

In all, 30 patients underwent 32 mPCNL procedures. The mean stone size was 17 (10.75-21.25) mm and the mean number of stones was 1 (1-2). The median stone clearance rate was 96.5 (95-100)%. The complication rate was 9.3%. No patient required a transfusion. In addition to these outcomes, we noted that the MIP system has many advantages over conventional PCNL (cPCNL). It is easy to learn and can be performed in both supine and prone positions. It is safe for supracostal puncture, provides excellent access to nearly all calyces and upper ureter, has multiple stone treatment options, can be used as an adjunct to cPCNL, and can be performed as a tubeless procedure.

CONCLUSION

Our experience with the MIP system has shown several advantages over cPCNL. mPCNL with the MIP system has several features that suggest it should be considered as an alternative or adjunct to cPCNL, ureteroscopy and extracorporeal shockwave lithotripsy.

Tubeless mini-percutaneous nephrolithotomy versus retrograde intrarenal surgery for lower calyceal stones of ⩽2 cm: A prospective randomised controlled study

Objective

To assess the safety, efficacy, and stone-free rate (SFR) of mini-percutaneous nephrolithotomy (mini-PCNL) and retrograde intrarenal surgery (RIRS) for the management of lower calyceal stones of ⩽2 cm, and to determine the advantages and disadvantages of each.

Patients and methods

In all, 120 patients with lower calyceal stones of ⩽2 cm were randomly divided into two equal groups: Group A were managed by mini-PCNL and Group B by RIRS using flexible ureteroscopy and laser. The mean age, sex, stone size, operating time, complications, hospital stay, and SFR were compared between the groups. The success of the procedure was defined as the absence of residual stones or small residuals of ⩽0.2 cm on computed tomography at 12 weeks postoperatively.

Results

Both groups were comparable for preoperative parameters. The mean (SD) operating time was statistically significantly longer in Group B [109.66 (20.75) min] as compared to Group A [71.66 (10.36) min]. Although the hospital stay was longer in Group A as compared to Group B this was not statistically significant (P = 0.244). The SFR for Group A was 92.72% and for Group B it was 84.31%, which was not significantly different (P = 0.060).

Conclusion

For treating lower calyceal stones of ⩽2 cm mini-PCNL and RIRS are comparable. Mini-PCNL had a better SFR than RIRS but the hospital stay was longer and there were more intraoperative complications, whilst, RIRS had a significantly longer operating time compared with mini-PCNL and a higher incidence of postoperative fever, and a lower SFR.