Percutaneous nephrolithotomy versus retrograde intrarenal surgery on mid-sized lower calyx stones– a systematic review of last decade

Abstract

Background

To systematically assess the effectiveness and safety of retrograde intrarenal surgery (RIRS) versus percutaneous nephrolithotomy (PCNL) in treating lower pole stones.

Methods

PubMed, Ovid MEDLINE, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE were researched to identify relevant studies up to May 2018. Based on keyword searches, we explored 1972 studies; following screening and eligibility evaluation, 414 studies were removed for various reasons, including 11 possibly relevant studies for this systematic review. A total of 1342 patient data were interpreted (PCNLn = 688; RIRS n = 654).

Results

The stone-free rate (SFR) in ten studies following the PCNL operation varies from 68 to 98.3%, while after the RIRS procedure, it ranges from around 46–93.7%. Out of 10 investigations, 7 demonstrated a superior SFR for the PCNL technique compared to the RIRS. Of the ten investigations, eight demonstrated reduced surgical durations using the PCNL method compared to the RIRS procedure. The duration of hospital stays for the PCNL treatment varies from around 0.3 ± 0.04 to 5.3 ± 1.20 days, while the duration for RIRS procedures ranges from 0 to 3.2 ± 0.52 days. All nine trials indicated a reduced period of hospital stay with the RIRS technique compared to the PCNL procedure. The complication rates in 10 studies following the PCNL surgery varied from approximately 2–72%, while those after the RIRS procedure ranged from about 4–21.6%. Out of 10 trials, 6 demonstrated a reduced complication rate with the RIRS technique compared to the PCNL.

Conclusion

The majority of studies in this systematic review indicate that the PCNL method exhibits a superior SFR, reduced operational duration, prolonged hospital stay, and increased complication rates compared to the RIRS procedure.

Clinical trial number

Not applicable, as this is a systematic review.

Introduction

In recent years, the incidence of urinary system stone disease has been increasing due to reasons such as the increase in the elderly population, increasing obesity rate, poor eating habits, inadequate fluid intake, and sedentary lifestyle [1]. With increasing incidence, stone surgery continues to develop with operation techniques and technological advances. Technological advances in the last 30 years have revolutionized the treatment of urinary system stone disease. In the past, urinary system stone diseases were treated with open surgery. In the following years, percutaneous nephrolithotomy (PCNL) and shock wave lithotripsy (SWL) treatments took their place on the agenda. The frequency of retrograde intrarenal surgery (RIRS) has increased thanks to technological advances [2]. When the European Urology Guide is reviewed, one can see that PCNL is preferred in treating kidney stones 2 cm and larger. Smaller stones may be treated by external shockwave lithotripsy or RIRS despite suboptimal results for stones between 15 and 20 mm. Treatment for stones smaller than 2 cm is decided according to the stone’s location and the calyx’s structure, as well as the stone’s hardness and the patient’s expectations [3]. Developments in subheadings such as patient position, access techniques, mini percutaneous methods, PCNL-RIRS combination, and 3-dimensional demonstration of the stone can help us predict the future [2, 3].

Prior meta-analyses have evaluated the results of the two procedural methods, concluding that PCNL produces better surgical outcomes than RIRS. Nonetheless, their findings about postoperative complications and associated factors are contradictory. Due to the limitations in quality and sample size of the studies covered, previous study results require confirmation through prospective large-scale studies. In recent years, numerous well-structured Randomized Controlled Trials (RCTs) on this topic have been published, yet a consensus on the conclusions remains elusive [4].

Consequently, we intended to integrate and analyze the latest papers to establish data about the comparative efficacy and safety of PCNL and RIRS procedures for treating lower-pole renal stones (LPS). This initiative supports clinical decision-making by elaborating insights on stone-free rate (SFR), operative time, hospital stay, and overall complications.

Method

A systematic literature search was conducted on PubMed, SCOPUS, COCHRANE Central Register of Controlled Trials, and EMBASE to identify original peer-reviewed articles until December 2024. The criteria of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the European Association of Urology (EAU) recommendations were followed. Retrograde intrarenal surgery and PCNL were assessed for comparative analysis. The principal endpoint was the SFR. Fig. 1 denotes the search approach and qualifying criteria for the systematic meta-analysis.

Fig. 1

PRISMA Flowchart for article enrollment

Literature search

The search utilized the following algorithm: ‘PCNL,’ ‘flexible ureteroscopy,’ ‘FURS,’ ‘retrograde intra-renal surgery,’ or ‘RIRS.’ The evidence level (LE) of each included trial was assessed based on the standards established by the European Association of Urology (EAU) Guidelines, and upon consensus regarding the final set of articles, two physicians (N.A, M.D) independently evaluated the quality of each article utilizing the Downs and Black checklist, which rated the quality of both randomized and nonrandomized trials. Additionally, those two writers reviewed the titles and abstracts of citations and acquired the complete texts of possibly eligible studies and any discrepancies. The reference lists of obtained papers were further examined for further qualifying publications.

A total of 1972 publications reviewed, published between 2001 and December 2024, met the eligibility criteria. The study included subjects with lower pole stones treated with RIRS or PCNL. Two corresponding authors responded to our inquiries to provide supplementary information.

Eligibility criteria

The inclusion criteria for the studies selected for the final analysis were as follows: [1] Language restricted to English; [2] Lower calyx renal stones around 1–3 cm measured by CT-Scan examination; [3] Patients who underwent PCNL or RIRS procedure; [4] Comparative studies must report at least one of the following outcomes for both PCNL and RIRS: SFR, operative time, length of hospital stay, and overall complications. Studies on [1] pediatric patients aged less than 18 years and [2] studies disseminated as conference abstracts or posters were excluded.

Data extraction and outcomes

The following information was recorded regarding each eligible study: author’s name, journal of publication, year of publication, country of origin, study type, total number of patients, and patient demographics. One initial search yielded 1972 studies, but only eleven were included in the final analysis based on eligibility criteria. The study’s flowchart is shown in Fig. 1.

Results

We explored 1972 studies based on keyword searches, following screening and eligibility evaluation, in the end, 11 relevant articles were selected for this systematic review [5,6,7,8,9,10,11,12,13,14,15]. Of the 11 possibly relevant research, 5 were prospective randomized controlled trials [5, 8,9,10,11], one was prospective [7], and five were retrospective analyses [6, 12,13,14,15]. All studies included were unblinded, with durations ranging from around seven months to five years and follow-up periods from one to twelve months. The investigations encompass patients with lower calyx renal stones measuring 1 to 3 cm as determined by a CT scan. In this comprehensive assessment of 1342 patients, 688 underwent PCNL surgery, while 654 underwent RIRS [5,6,7,8,9,10,11,12,13,14,15] (Table 1).

Table 1 Demographic characteristics of PCNL compared with RIRS on lower pole calyx stone patients of the included studies

Clinical outcomes

Participants with lower pole calyx stones measuring 1.0–3.0 cm underwent PCNL (n = 688) and RIRS (n = 654) procedures. The SFR, operation time, length of hospital stay, and complications were evaluated (Table 2).

Table 2 The outcome assessed of PCNL compared with RIRS on the included studies’ lower pole calyx stone patients

Stone-free rate

Out of 11 trials, 10 indicated SFRs after PCNL or RIRS treatments [5,6,7,8,9, 11,12,13,14,15]. A majority of the studies defined stone-free status as the absence of stones found by imaging scans following a median post-intervention follow-up of 4 months (Table 1). The SFR in ten studies following the PCNL operation varies from 68 to 98.3%, while after the RIRS procedure, it ranges from around 46–93.7%. Out of 10 investigations, 7 demonstrated a superior SFR for the PCNL technique compared to the RIRS [5, 6, 8, 9, 13,14,15]; conversely, two studies indicated a higher SFR for the RIRS procedure [11, 12], while 1 study reported comparable rates for both PCNL and RIRS procedures [7] (Table 2).

Duration of operation time

Ten of the eleven trials reported operative time after PCNL or RIRS procedures. The operation duration of the PCNL operation varies from approximately 46.2 ± 24.3 to 85.5 ± 41.1 min, while the operative duration of the RIRS technique ranges from approximately 55.8 ± 11.4 to 273 min [5,6,7,8,9,10, 12,13,14,15]. Of the ten investigations, eight demonstrated reduced surgical durations using the PCNL method compared to the RIRS procedure [5, 7,8,9, 11,12,13,14,15]. Nevertheless, using the RIRS method, we identified two studies indicating a reduced surgical duration [6, 10] (Table 2).

Duration of hospital stay

Nine of 11 trials indicated hospital admissions subsequent to PCNL or RIRS procedures. The duration of hospital stays for the PCNL treatment varies from around 0.3 ± 0.04 to 5.3 ± 1.20 days, while the duration for RIRS procedures ranges from 0 to 3.2 ± 0.52 days. All nine trials indicated a reduced period of hospital stay with the RIRS technique in comparison to the PCNL procedure [5,6,7,8, 10, 12,13,14,15].

Complication rates

Of the 11 trials, 10 reported problems following PCNL or RIRS treatments. Most studies categorized problems as any intra-operative and post-operative minor and major complications, with some employing the Clavien-Dindo classification for grading complications. The complication rates in 10 studies following the PCNL surgery varied from approximately 2–72%, while those after the RIRS procedure ranged from about 4–21.6% [5,6,7,8,9,10, 12,13,14,15]. Out of 10 trials, 6 demonstrated a reduced complication rate with the RIRS technique compared to the PCNL method [6,7,8, 12, 15]. Nevertheless, four studies indicated reduced complication rates associated with PCNL [5, 9, 10, 13, 14] (Table 2).

Discussion

The treatment of lower pole stones encompasses observation, RIRS, and PCNL. The decision between RIRS and PCNL often hinges on the patient’s circumstances. Our systematic analysis aimed to identify an improved protocol for individuals with renal stones in the lower pole calyx [16]. The findings of our investigation are consistent with prior systematic reviews and meta-analyses. Our study revealed that the PCNL treatment demonstrated a shorter operating duration compared to the RIRS method in certain instances. The RIRS procedure demonstrated a reduced hospital stay duration and a decreased complication rate compared to the PCNL operation. Our systematic review also indicated that PCNL and RIRS procedures are advantageous for patients; nevertheless, additional meta-analysis is required to derive more objective results and elucidate the benefits of these procedures. For clarity and ease of comparison, Fig. 2 provides a visual overview of how included studies distributed their conclusions between PCNL and RIRS across different clinical parameters.

Fig. 2

Percentage of studies favoring PCNL or RIRS for each clinical outcome in lower pole stone management

As per the EAU, the first-line treatment option for calculi less than 2 cm is RIRS [17]. Recent advancements in RIRS technology have established it as a viable therapeutic alternative for bigger renal calculi. Although mPCNL exhibits a greater SFR, its complication rate parallels that of RIRS, albeit with a longer duration of inpatient hospitalization. A more extended inpatient stay is generally attributed to an indwelling nephrostomy tube for drainage and/or ongoing postoperative discomfort. Increased complications and extended hospitalizations will undoubtedly result in elevated expenses for supplementary laboratory testing, medical assessments, and heightened demands for analgesics and antibiotics [18].

Dutta et al. [5] conducted a prospective, randomized, controlled clinical trial using a 2-mm residual stone burden cutoff. MPCNL (n = 51) was more likely to render patients SFR than RIRS (n = 50). In contrast, Shabana et al. [6]. reported comparable duration of hospital stay, SFR, and complication rates between mPCNL and RIRS in treating 10–20 mm lower calyceal stones using propensity score matching analysis. The study of Zhang et al. [8] compared mPCNL, SWL, and RIRS on the treatment of 1–2 cm lower pole kidney stones. They elaborated that all techniques were safe and effective, but mPCNL and RIRS were more effective than SWL at a SFR. They also noted that mPCNL was more associated with complications, and the operation time was longer in RIRS [8]. Fayad et al. [9] stated that mPCNL had a better SFR than RIRS for managing lower calyceal stones of ⩽2 cm. Still, the hospital stay was more extended, and there were more intraoperative complications. RIRS had a significantly longer operating time than mPCNL, a higher incidence of postoperative fever, and a lower SFR. Armagan et al. [13]. and Koyuncu et al. [14]., and Kirac et al. [15] found comparable SFRs between mPCNL and RIRS in their retrospective analysis.

One of the RCTs analyzed in this systematic review was conducted by Dutta et al. [5] to compare ureteroscopy vs. prone mPCNL to treat lower real stones (1–2 cm). There was no difference in the number of postoperative complications that occurred within thirty days, the requirement for a secondary procedure within thirty days, or the change in creatinine levels from before to after the operation. The duration of the operation did not differ considerably. In the group that underwent mPCNL, the average length of stay was much longer. At the end of the study, they concluded that RIRS was less likely to result in patients being stone-free than mPCNL. The two techniques did not differ in the proportion of complications, surgery times, or operating margins [5].

In a randomized trial by Perri et al. [20]., they compared the outcomes of mPCNL and RIRS utilizing the SuperPulsed thulium fiber laser for treating 10 mm and 20 mm renal calculi. They stated that the SFRs were analogous between the two techniques. They noted that RIRS exhibited a statistically significant greater SFR, particularly for upper calyceal stones. The results indicate that RIRS with the SuperPulsed thulium fiber laser may provide a superior option to mPCNL, particularly for upper calyceal calculi [20]. In our review, we have also included the randomized study of Fayad et al. [9] that compared RIRS and PCNL. Their research indicated that RIRS and PCNL produced similar SFRs. Furthermore, they exhibited a clear benefit of RIRS by lowering the risk of hemorrhagic complications and decreasing the probability of transfusion necessity [9].

Unlike the studies included in this systematic review, Lv et al. [21]. investigated the removal of stones > 2 cm via RIRS and mPCNL. They sought to establish comparable groups by propensity score matching for a more dependable comparison. The study demonstrated that RIRS and mPCNL attained comparable SFRs, indicating that both techniques efficiently addressed kidney stones of this magnitude. The study revealed specific benefits of RIRS compared to mPCNL regarding hospital duration and complication rates [21]. In another study on bigger renal stones (2–4 cm), Lai et al. [22]. compared RIRS with vacuum-assisted UAS (V-UAS) and mPCNL. The duration of surgery was significantly longer in RIRS patients than in individuals operated on via mPCNL. Despite the mPCNL group exhibiting a markedly higher beginning SFR (73.2% vs. 50%, P = 0.035), the ultimate SFR was similar between the RIRS and mPCNL groups (89.3% vs. 92.9%, P = 0.681) [22]. Those two studies were excluded as the sizes of the stones were larger than those included in the trials in our review.

Rodrigues et al. [23] conducted a retrospective analysis to compare mPCNL (n = 21) and RIRS (n = 42) for stones measuring up to 1550 mm³. The patients were monitored using computed tomography during the postoperative period. The SFRs were comparable among the groups (76.2% vs. 66.7%, p = 0.42, and 90.5% vs. 85.7%, p = 0.57). The complication rate was comparable (26.1% vs. 9.6%, p = 0.188), although mPCNL resulted in prolonged hospitalization and fluoroscopy duration (p = 0.001 for both).

RIRS is inferior to PCNL in the treatment of lower pole stones. Many randomized controlled trials have consistently shown that PCNL outcomes are markedly superior. SFR was compared to RIRS for managing lower pole stones [24]. Huang et al. [25] conducted a study on therapy selection for patients with lower pole stones measuring between 1 and 2 cm. The research findings indicated that multiple criteria are essential in ascertaining the suitable treatment strategy, including the number of stones, diameter, infundibulopelvic angle, infundibular length, and infundibular width. These criteria are critical factors in determining the appropriate treatment for renal stones in the lower pole, specifically when choosing between RIRS and PCNL [25]. Although PCNL is superior to RIRS in treating lower pole stones, meta-analyses have shown that the SFRs for RIRS and PCNL are comparable, particularly for kidney stones measuring 2–3 cm [16]. These analyses have demonstrated that RIRS can attain outcomes comparable to PCNL regarding success while displaying minimal rates of intraoperative problems [26,27,28,29,30].

De Shuba et al. [31]. conducted a systematic review and meta-analysis of two randomized and eight non-randomized studies to investigate the balance, advantages, and disadvantages of PCNL and RIRS for stones < 2 cm. PCNL techniques provided a significantly higher stone-free (p < 0.00001) but also higher complication rates (p < 0.01) and a more significant postoperative decrease in hemoglobin levels (p < 0.00001). In contrast, RIRS led to a shorter hospital stay (p < 0.0001). At subgroup analysis, RIRS provided a significantly higher SFR than minimally invasive percutaneous procedures (MIPPs) (p = 0.03) but less than standard PCNL (p = 0.0002). Hospital stay was shorter for RIRS than MIPPs (p = 0.003) and standard PCNL (p = 0.003). They concluded that given the added morbidity and lower efficacy of MIPPs, RIRS should be considered standard therapy for stones < 2 cm until appropriate randomized studies are performed. Regarding the patient-centric approach and quality of life, they proposed that treatment can be tailored to the patient by balancing the advantages and disadvantages of each technique [31]. Soderberg et al. [32]. analyzed 42 trials assessing the effects of PCNL versus RIRS in 4571 randomized participants. They reported that PCNL, compared with RIRS, may improve SFRs and reduce the need for secondary interventions but probably has little or no effect on major complications. PCNL, compared with RIRS, may have little or no impact on ureteral stricture rates and may increase the length of hospital stay. We found no evidence of unplanned medical visits or participant quality of life and indicated that a case-by-case approach is recommended for patient-centric decision-making [32].

The introduction of a flexible and navigable suction access sheath (FANS) has improved the SFR. Shrestha et al. [33] collected data from 25 centers, including 394 adult patients undergoing ureteroscopy using FANS for lower pole stones (LPS). Out of 394 patients, non-LPS (group 1) comprised 268, and the rest of 126 patients had LPS (group 2). Single-stage zero fragment SFR was seen in 58.6% (group 1) vs. 54.8% (group 2) (p = 0.619). Single-stage grade A + B SFR was achieved in 96.6% vs. 98.4% in groups 1 and 2, respectively. On multivariate analysis, Thulium fiber laser use was significantly associated with higher odds of being grade A stone-free, while stone volume had lower odds. In the LPS group, only two patients needed reintervention. The highest complication grade was Clavien 2, which was seen in the 3.2% LPS group. Gauhar et al. [34]. assessed retrograde intrarenal surgery outcomes in 50 children using ClearPetra, a flexible and navigable suction ureteral access sheath (FANS-UAS). They declared that FANS-UAS is feasible and safe, with a low rate of complications and an excellent SFR in pediatric patients. Regarding those new data, using FANS-UASs for lower pole stones is effective and safe. The SFR of lower pole stones is comparable to that of non-lower pole locations, with a very low reintervention rate in both groups. The advancements in laser technologies and the introduction of FANS could provide a forward-looking perspective and enhance outcomes for pure lower pole stones [33, 34].

Limitations

This systematic review has certain limitations. A meta-analysis could not be conducted due to the heterogeneity of studies, and the lack of access to individual patient data. The included studies also varied in terms of methodology, and follow-up durations. These factors may have limited the comparability of results and the ability to generate pooled estimates.

Conclusion

The majority of studies in this systematic review indicate that the PCNL method exhibits a superior SFR, reduced operational duration, prolonged hospital stay, and increased complication rates compared to the RIRS procedure. Evaluating patient-specific factors, including stone placement and burden, is essential while determining the suitable therapeutic strategy.