ESWL, PNL (micro/mini), and RIRS are considered well-established, acceptable treatment options for children with kidney stones, as they have shown effective outcomes in adult patients. Pediatric patients are considered to be at high risk for recurrent kidney stone disease [1]. ESWL was first applied to adult kidney stone patients in the 1980s, and over time, it became accepted as the primary treatment for pediatric patients with kidney stones smaller than 20 mm [7]. Nevertheless, the treatment was controversial due to its detrimental effects on kidney parenchyma, with long-term results related to this effect on developing kidneys [8, 9, 12]. Due to factors such as resistance to ESWL and the need for multiple treatment sessions, there has been an increase in the exploration of alternative treatment modalities. The first data on PNL treatment in pediatric kidney stone disease management has been published by Woodside et al., incorporating similar results regarding the effectiveness of the treatment compared to that in adult patients but with a lower incidence of complications and shorter duration of hospital stay [13]. According to Desai et al.’s study [5], based on 56 pediatric PNL patients, a stone-free rate of 90% was achieved. The study also reported a correlation between the amount of bleeding and the number of renal accesses, emphasizing that the calibration of the Amplatz sheet is correlated with the amount of bleeding. The use of Amplatz sheaths smaller than 22 F was recommended in this study to minimize hemorrhagic complications. Nonetheless, injury to neighboring organs, especially complications arising while accessing renal stones in the upper calyx during the PNL procedure, has raised questions about the safety of this procedure in pediatric patients [14, 15]. The development of new optic systems, flexible URS, the intervention of the ho-YAG laser lithotripsy, and increased surgical experience have made the efficient use of RIRS feasible for treating renal stones in children. The first extensive study on the treatment of pediatric renal stones in children was published by Cannon et al. in 2007 (14). In a study involving 21 pediatric patients with lower calyx stones, a stone-free rate of 76% was reported after the RIRS procedure, with no intraoperative complications. In the same study, the authors reported that preoperative stent placement for passive dilatation was used in 38% of the cases, and a ureteral access sheath (UAS) was used during the procedure in 43% of the cases [16]. Another study, which included 100 pediatric cases, reported a stone-free rate of 91%, with ureteral perforation complications in 5 cases, necessitating ureteral reimplantation in 1 case due to ureteral stricture [17]. No intraoperative complications were reported in another study of 56 pediatric patients with renal stones less than 15 mm in diameter who underwent preoperative double J stent placement preceding the RIRS procedure. However, in the postoperative period, 3 patients suffered from urinary infection and 1 patient was exposed to macroscopic hematuria [18]. These results highlight the emerging importance of RIRS as a feasible, minimally invasive treatment option for nephrolithiasis among pediatric patients, with high stone-free rates and adequate safety.

In our series, we did not routinely insert a double J stent for passive ureteral dilation before the procedure. During the study, we refrained from using UAS due to the young mean age of our patient cohort, considering the risk of ureteral perforation. However, in 24 cases where we encountered difficulty passing through the ureteral orifice, we inserted a double J catheter for dilatation purposes and repeated the procedure one month later. Tanaka et al. reported a correlation between the success rate of the RIRS procedure, the size of the stone, and the age of the patient in a study involving 50 pediatric patients [19]. Unsal et al.’s [20] study evaluating the effectiveness of the RIRS procedure in preschool-age children (under 7 years old) reported a 100% stone-free rate for renal stones smaller than 10 mm and an 81% stone-free rate for stones larger than 10 mm. Passive ureteral dilation was required in 37.5% of incidences. This study included the youngest pediatric patient (10 months old) undergoing the RIRS procedure in the literature, with a mean stone size of 11.5 mm. In this study, UAS was used in 17.6% of cases, and one case of ureteral perforation was reported as a complication during ureteral dilatation. While routine fluoroscopy was used in all the pediatric RIRS cases mentioned above, our study executed the procedure successfully without fluoroscopic intervention. The youngest patient in our study sample was 6 months old at the time of the procedure, and to our knowledge, this was the youngest patient to undergo the RIRS procedure in the literature. Our study achieved a stone-free rate of 82.9%, which is consistent with the literature. The average operation time of 51 (31–98) minutes obtained in our study is similar to that reported in previous studies [10]. The size of the stone is the most important known risk factor affecting the duration of the operation. The average stone size in our study was 9.3 mm. Our statistical analysis has shown that the stone size and the number of stones correlate with the operation duration obtained in the study in a positive way, which was in accordance with existing literature [10, 21].

The use of fluoroscopy is essential for ensuring the safety of RIRS procedures [22]. While performing Retrograde Intrarenal Surgery (RIRS), the use of fluoroscopy is crucial for managing Ureteral Access Sheath (UAS) and stent placement, as well as addressing any residual stones and potential urinary tract perforations. However, it is important to note that fluoroscopy usage may lead to certain health risks, including infertility, genetic mutations, and increased likelihood of cancer, for both surgical teams and patients [23]. The severity of potential radiation effects is directly related to the dose and duration of exposure. Therefore, protective equipment is vital to minimize harm. Despite adopting stringent protective precautions, exposure to radiation during the RIRS procedure remains inevitable, affecting both the surgical team and patients [24]. In a study evaluating fluoroscopy time in pediatric patients undergoing RIRS, the mean fluoroscopy time was 33 ± 15 s. Although this period is relatively short compared to PNL, patients are still exposed to significant radiation. During the classic RIRS procedure, the initial step involves the placement of the guidewire catheter safely by using the semirigid URS under direct visualization until it reaches the renal pelvis. To avoid radiation exposure, we did not use fluoroscopy. The UAS placement process usually entails sliding the sheath over the guidewire catheter with the help of fluoroscopy. However, we opted for an alternative approach that did not require UAS at all. It is known that flexible URS could lead to high renal pelvic pressure (RPP) with a high probability of absorption of irrigation fluid, bacteria, and endotoxin into the bloodstream, resulting in acute complications such as systemic inflammatory response syndrome, sepsis, and long-term complication of renal function impairment. It is known that UAS could reduce the RPP to a certain extent, but it still cannot control and monitor the RPP to reduce the incidence of pressure-related complications [25]. Notably, we did not encounter any complications related to the absence of a UAS during the procedure embraced in our study. Although we did not encounter any serious complications due to increased pelvicalyceal pressure despite not using UAS in our study, there is still a need for large-scale research studies to conclude that the no-UAS method is safe and effective and is a reliable alternative to the classical fluoroscopy-guided method.

As a result, we did not need fluoroscopy, which means that there was no risk of exposure to harmful radiation. Although a similar success rate was reported in a prior study in our country where RIRS was performed without the use of fluoroscopy, our study’s superiority lies in the fact that all procedures, including guide wire placement, were performed under direct visualization. Furthermore, UAS was not included in any of the cases, and the number of cases was higher in our study [10]. The advantages of this study can be defined as being multicenter, being the largest series study conducted in pediatric patients without the use of access sheath, including the youngest age group of patients to the best of our knowledge. However, the study has limitations, including a relatively small sample size, retrospective nature, and lack of a control group. Since neither center used fluoroscopy in pediatric RIRS patients, no data regarding the method of using fluoroscopy-guided procedures in children were available, which would have been valuable for creating an age-matched control group.