Our study aimed to compare the efficacy and safety of the FURS procedure performed with two different techniques namely FANS versus DISS in the management of large ( 2–3 cm) lower pole renal stones. While the SFR after the first session was lower in the DISS group, the overall SFR after two sessions was comparable and exceeded 80% in both groups. This finding clearly demonstrates that both methods can achieve high success rates with additional sessions. However, despite comparable success rates, our findings showed a longer operation time against DISS, a critical disadvantage that can be attributed to the dusting effect used in stone pulverization, which definitely requires a longer time for effective stone evacuation. Previous studies have demonstrated that mini-PCNL offers superior single-session SFRs for renal stones in the 2–3 cm range [10]. However, PCNL techniques are associated with higher complication rates, which may sometimes be severe enough to include bleeding, infection, and renal parenchymal injury [5]. On the other hand, there are also studies suggesting that there is no significant difference in complications between the two procedures when mini-PCNL and FURS are compared for the treatment of lower calyceal stones [11]. Our current results demonstrate that as acceptable alternative options, both FANS and DISS could provide efficient and safe outcomes in the minimally invasive management of 2–3 lower calyceal stones in a staged manner. Although not statistically significant, the slightly higher single-session SFR observed with FANS may be attributed to its enhanced fragment evacuation via direct suctioning, potentially minimizing the need for prolonged dusting and irrigation.

Several previous studies have assessed the efficacy of FANS and DISS in endoscopic stone management. According to some of these studies, FANS in flexible ureteroscopy resulted in a significantly shorter operative time and improved fragment retrieval efficiency compared to the use of conventional access sheats [12]. Similarly, outcomes of some studies revealed that DISS reduced intrarenal pressure and facilitated better visualization, although prolonged operational time [13, 14]. These findings align well with our current results, highlighting the trade-off between better evacuation efficiency in FANS and prolonged operative times in DISS. When interpreting these findings, it should be kept in mind that as the main advantage of the technique we applied; patients in the DISS group did not require the use of an extra access sheath. Given the well-documented risks associated with access sheaths, their avoidance in this group may be beneficial [15].

Additionally, recent reviews have suggested that suction techniques offer slightly higher SFRs in the first session, minimizing the risk of infectious complications [16]. This aligns with our observation that postoperative fever rates were comparable between the patients of both groups, despite the different suction mechanisms employed.

Moreover, recent advancements in laser technology, particularly thulium fiber laser (TFL), may further enhance stone pulverization efficiency and reduce operative time. TFL has been shown to provide superior fragmentation rates with reduced retropulsion, potentially increasing SFR and shortening procedure duration compared to conventional 35 W holmium: YAG lasers [17]. TFL technology, in combination with smaller laser fibers and advanced accessories, has significantly improved the effectiveness and safety of lower pole stone management. The combination of TFL with different suction devices is increasingly reported as a promising method that can greatly enhance stone-free rates (SFR) by facilitating better fragment clearance and minimizing intrarenal pressure [18]. It was not difficult to predict that in future studies, as a less invasive alternative than PNL approaches, a combination of FANS and DISS methods with TFL could achieve higher SFR ​​in a single session. In the treatment of medium-sized lower calyceal stones.

To summarize, when comparing our findings with the data reported so far on PCNL approaches in the literature so far, it is important to note that PCNL generally achieves single-session SFRs exceeding 90% for similar stone size and location [19]. However, this benefit comes at the expense of significantly higher morbidity, including an increased risk of severe complications such as sepsis, hemorrhage, and prolonged hospitalization [20]. In light of these facts, our study underscores the viability of FURS-based approaches as less invasive alternatives, particularly for patients who prioritize a reduced risk profile over immediate single-session stone clearance.

One potential limitation of our study is the lack of a PCNL or mini-PCNL control group. However, it is crucial to emphasize that our objective was not to compare these already well-established techniques but rather to determine the efficacy of FANS and DISS techniques in a comparative manner The efficacy of PCNL and mini-PCNL for renal stones in this size range has been extensively validated in prior studies, and thus, their omission should not be considered a major limitation of our analysis.

Another limitation is the retrospective nature of our study, which may introduce selection bias. Additionally, the relatively small sample size could have negatively affected the statistical power of our findings. A larger cohort might have provided more definitive conclusions regarding the comparative efficacy of FANS and DISS. However, taking the highly limited data reported so far on this issue in the literature, we believe that our current results will be contributive enough to the published information. Future prospective studies with a larger number of participants are necessary to validate our results and strengthen the statistical significance of our observations.