The best treatment approach for lower calyceal stones ≤ 20 mm in maximal diameter: mini percutaneous nephrolithotripsy, retrograde intrarenal surgery or shock wave lithotripsy. A systematic review and meta-analysis of the literature conducted by the European Section of Uro-Technology and Young Academic Urologists

Innovative approaches to large lower calyceal stones (10-20 mm): evaluating modified T-tilt position and lower calyx hydrodilatation techniques in flexible ureteroscopy versus hydrodilatation alone: prospective randomized controlled study

BACKGROUND

Managing lower calyceal stones poses significant challenges. Flexible ureteroscopy and laser lithotripsy (FURSL) are standard techniques for treating large stones (10-20 mm).

OBJECTIVE

This study evaluates the role of the T-tilt position (45-degree Trendelenburg with a 45-degree lateral tilt against the side of the stone) and hydrodilatation of the lower calyx with 50 cc saline injection as needed in optimizing stone-free rates and safety during FURSL for lower calyceal stones.

METHODS

Following ethical approval, a prospective randomized study with 197 patients was conducted. 13 patients were excluded (9 with renal anomalies or prior surgeries affecting anatomy, and four who refused participation). The remaining 184 were randomized into Group A (92 patients in T-tilt with hydrodilatation) and Group B (92 patients with hydrodilatation in lithotomy position). Randomization was achieved with computer-generated numbers stored in sealed envelopes. All patients had 10-20 mm stones and underwent FURSL using a 7.5 FR flexible ureteroscope and 200-micron Wolf laser fiber. Follow-up CT KUB was performed at 1 and 3 months, assessing stone-free status (no residual stones or residual < 3 mm) and the need for auxiliary procedures.

RESULTS

Both groups were statistically analyzed for age, sex, BMI, stone size, Hounsfield units (HU), infundibular dimensions, access sheath use, complications (fever, sepsis, hematuria) and hospital stay. No significant differences were found between the two groups in these variables. However, operative time was significantly longer in Group A than in Group B (P value = 0.018). The need for auxiliary procedures was significantly lower in Group A than in Group B (P value = 0.001), and the success rate was significantly higher in Group A than in Group B (P value = 0.001).

CONCLUSION

The T-tilt position and hydrodilatation significantly optimize outcomes and enhance stone-free rates for large lower calyceal stones (10-20 mm). This position improves intraoperative vision and facilitates access to the lower calyx, facilitating the clearance of stone fragments.

External validation of a nomogram for outcome prediction in management of medium-sized (1-2 cm) kidney stones

BACKGROUND

Stone nomogram by Micali et al., able topredict treatment failure of shock-wave lithotripsy (SWL), retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PNL) in the management of single 1-2 cm renal stones, was developed on 2605 patients and showed a high predictive accuracy, with an area under ROC curve of 0.793 at internal validation. The aim of the present study is to externally validate the model to assess whether it displayed a satisfactory predictive performance if applied to different populations.

METHODS

External validation was retrospectively performed on 3025 patients who underwent an active stone treatment from December 2010 to June 2021 in 26 centers from four countries (Italy, USA, Spain, Argentina). Collected variables included: age, gender, previous renal surgery, preoperative urine culture, hydronephrosis, stone side, site, density, skin-to-stone distance. Treatment failure was the defined outcome (residual fragments >4 mm at three months CT-scan).

RESULTS

Model discrimination in external validation datasets showed an area under ROC curve of 0.66 (95% 0.59-0.68) with adequate calibration. The retrospective fashion of the study and the lack of generalizability of the tool towards populations from Asia, Africa or Oceania represent limitations of the current analysis.

CONCLUSIONS

According to the current findings, Micali's nomogram can be used for treatment prediction after SWL, RIRS and PNL; however, a lower discrimination performance than the one at internal validation should be acknowledged, reflecting geographical, temporal and domain limitation of external validation studies. Further prospective evaluation is required to refine and improve the nomogram findings and to validate its clinical value.

[The 1-cm lower calyx calculus: SWT, URS or Mini-PCNL? Guidelines vs. reality.]

Urinary stones of the upper urinary tract can be considered a widespread public health concern due to their high incidence and prevalence and their health policy-related and financial implications. A significant proportion of newly diagnosed kidney stones are lower-pole stones, i.e., stones affecting the lower calyx group of the renal pelvicalyceal system. These are often diagnosed by chance, i.e., as incidental findings during ultrasound or CT scans performed for other reasons, or as "secondary stones" detected during the diagnostic work-up of symptomatic urinary stones in other locations. Residual disintegrates after extracorporeal shock-wave lithotripsy (ESWL) or endoscopic stone therapy constitute a further, quantitatively significant group. These incidentally discovered lower-pole stones are often characterised by their small size and lack of symptoms. It stands to reason that some of these small, asymptomatic lower-pole stones do not always remain small and asymptomatic, and that treatment tends to become more complex with increasing size. There has been an astonishing lack of published studies with a high level of evidence over the last 20 years to provide a conclusive and reproducible answer to the question posed in this review. Small, asymptomatic stones can be monitored. Symptomatic and rapidly growing stones should be treated. There is a lack of valid risk factors allowing an identification of subgroups that should be treated prophylactically at the asymptomatic stage. In active therapy, a 10-to-20-year-old principle still holds true today: a high stone-free rate in one therapy session is offset by an increased complication rate, with increasing miniaturisation in endourology (retrograde and percutaneous) and increasingly effective laser disintegration shifting this basic principle more and more in favour of flexible URS and (mini, micro) PCNL. The range of indications for ESWL is undoubtedly becoming smaller, and this also applies to lower-pole stones. The results of an ongoing prospective randomised study comparing the different treatment modalities, albeit with recruitment difficulties, are still pending.

The role of 'artificial intelligence, machine learning, virtual reality, and radiomics' in PCNL: a review of publication trends over the last 30 years

Introduction

We wanted to analyze the trend of publications in a period of 30 years from 1994 to 2023, on the application of 'artificial intelligence (AI), machine learning (ML), virtual reality (VR), and radiomics in percutaneous nephrolithotomy (PCNL)'. We conducted this study by looking at published papers associated with AI and PCNL procedures, including simulation training, with preoperative and intraoperative applications.

Materials and Methods

Although MeSH terms research on the PubMed database, we performed a comprehensive review of the literature from 1994 to 2023 for all published papers on 'AI, ML, VR, and radiomics' in 'PCNL', with papers in all languages included. Papers were divided into three 10-year periods: Period 1 (1994-2003), Period 2 (2004-2013), and Period 3 (2014-2023).

Results

Over a 30-year timeframe, 143 papers have been published on the subject with 116 (81%) published in the last decade, with a relative increase from Period 2 to Period 3 of +427% (p = 0.0027). There was a gradual increase in areas such as automated diagnosis of larger stones, automated intraoperative needle targeting, and VR simulators in surgical planning and training. This increase was most marked in Period 3 with automated targeting with 52 papers (45%), followed by the application of AI, ML, and radiomics in predicting operative outcomes (22%, n = 26) and VR for simulation (18%, n = 21). Papers on technological innovations in PCNL (n = 9), intelligent construction of personalized protocols (n = 6), and automated diagnosis (n = 2) accounted for 15% of publications. A rise in automated targeting for PCNL and PCNL training between Period 2 and Period 3 was +247% (p = 0.0055) and +200% (p = 0.0161), respectively.

Conclusion

An interest in the application of AI in PCNL procedures has increased in the last 30 years, and a steep rise has been witnessed in the last 10 years. As new technologies are developed, their application in devices for training and automated systems for precise renal puncture and outcome prediction seems to play a leading role in modern-day AI-based publication trends on PCNL.

A comparison among RIRS and MiniPerc for renal stones between 10 and 20 mm using thulium fiber laser (Fiber Dust): a randomized controlled trial

PURPOSE

We performed a prospective randomized comparison among Retrograde IntraRenal Surgery (RIRS) and MiniPerc (MP) for stones between 10 and 20 mm to evaluate outcomes with the same laser device: Fiber Dust.

METHODS

Patients with a single renal stone between 10 and 20 mm were randomized to RIRS (Group A) versus MP (Group B). Exclusion criteria were age < 18 or > 75, presence of acute infection, coagulation impairments, cardiovascular or pulmonary comorbidities. In both groups, the Fiber Dust laser was used. A CT scan after 3 months was performed. A negative CT scan or asymptomatic patients with stone fragments < 3 mm and a negative urinary culture were the criteria to assess the stone-free status. A statistical analysis was carried out to assess success, complication and retreatment rates and need for auxiliary treatments.

RESULTS

Between January 2021 and January 2022, 186 patients were enrolled (90 in Group A and 96 in Group B). Mean stone size was 15.8 mm and 14.9 mm in Group A and B, respectively (p = 0.23). The overall stone-free rate (SFR) was 73.3% for Group A and 84.4% for Group B. A higher SFR was reached for upper calyceal stones in Group A (90.4%) lower calyceal stones in Group B (91.6%). Retreatment rate (p = 0.31) and auxiliary procedure rate (p = 0.18) were comparable. Complication rate was 5.5% and 5.2% for Groups A and B, respectively.

CONCLUSIONS

RIRS and MP are both effective to obtain a postoperative SFR with Fiber Dust. According to the stone position one treatment is superior to the other one.

Mini percutaneous nephrolithotomy versus standard percutaneous nephrolithotomy for the management of renal stones over 2 cm: a systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Standard percutaneous nephrolithotomy (sPCNL) is recommended for renal stones over 2cm. Mini percutaneous nephrolithotomy (mPCNL) has also emerged as a promising technique in this setting. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing the safety and efficacy of sPCNL to mPCNL for the management of renal stones over 2cm.

EVIDENCE ACQUISITION

We systematically searched PubMed, Cochrane Library and Scopus databases until April 2021 and sources of grey literature for relevant RCTs. We performed a meta-analysis of odds ratios (ORs) to compare bleeding or other complications and stone-free rate (SFR) between sPCNL and mPCNL. Similarly, we undertook a metaanalysis of weighted mean differences for the mean operative and hospitalization time between the two techniques (PROSPERO: CRD42021241860).

EVIDENCE SYNTHESIS

Pooled data from 8 RCTs (2535 patients) were available for analysis. sPCNL was associated with a higher hemoglobin drop (0.59g/dl, 95%CI: 0.4-0.77, I2=93%), higher likelihood of postoperative blood transfusion (OR: 2.58, 95%CI: 1.03-6.45, I2=30%) and longer hospital stay (0.75 days, 95%CI: 0.45-1.05, I2=73%) compared to mPCNL. No significant differences were demonstrated in SFR (OR: 0.92, 95%CI: 0.74-1.16, I2=0%) and mean operative time (4.05 minutes, 95%CI: -9.45-1.37, I2=91%) after sPCNL versus mPCNL. Similarly, no significant differences were observed for postoperative fever, pain and Clavien-Dindo complications.

CONCLUSIONS

mPCNL represents a safe and effective technique and may be also recommended as a first-line treatment modality for well-selected patients with renal stones over 2cm. Still, further high-quality RCTs on the field are mandatory, since the overall level of evidence is low.