Comparison of robot-assisted and laparoscopic pyeloplasty with flexible ureteroscopy for managing concomitant ureteropelvic junction obstruction and renal calculi in children

Introduction

In the past 20 years, there has been a significant increase in the incidence of pediatric urolithiasis, with a prevalence rate of kidney stones in children reaching 5‰ (1). Ureteropelvic junction obstruction (UPJO) in pediatric patients is commonly complicated by renal stones, with an occurrence rate of up to 20% (2). The coexistence of UPJO and stones poses a challenge and difficulty in surgical procedures, as achieving anatomical reconstruction of the ureteropelvic junction (UPJ) and complete stone clearance in one operation is a major concern for urologists (3). Regardless of using laparoscopy alone or ureteroscopy alone, the stone clearance rate is less than 10%. Ureteroscopy alone cannot access the UPJ, and the small diameter of the ureter limits its application in infants and young children (1).

Due to UPJO and renal pelvic dilation, extracorporeal shock wave lithotripsy (ESWL) is generally ineffective in removing fragmented stones, so it is rarely used in pediatric patients. The use of laparoscopic techniques alone for UPJO with complex renal stones is often considered a challenging issue during laparoscopic pyeloplasty (LP), and therefore, it is considered a reason to opt for open surgery or to combine percutaneous nephrolithotomy (PCNL) with UPJO internal incision (4). Moreover, the surgeons choose to perform staged procedures with one-stage PCNL followed by LP.

In recent years, with the advancement of minimally invasive concepts and the continuous development of various endoscopic and minimally invasive diagnostic and therapeutic techniques, there are increasing options and less trauma in treating UPJO with concurrent stones in children (3,5). In adults, robot-assisted laparoscopic pyeloplasty (RALP) and LP combined with flexible ureteroscopy for UPJO concurrent renal stones has been widely recognized (6). However, there is a lack of large sample reports on its application in children. This study aims to compare the safety and efficacy of RALP and LP combined with flexible ureteroscopy in pediatric UPJO with renal calculi. We present this article in accordance with the STROBE reporting checklist (available at https://tp.amegroups.com/article/view/10.21037/tp-2024-557/rc).

Methods

Patients

This retrospective study included pediatric patients diagnosed with UPJO and renal calculi, treated between March 2018 and June 2023 at the Seventh Medical Center of the Chinese PLA General Hospital. Preoperative intravenous urography (IVU), emission computed tomography, computed tomography urography (CTU), and/or magnetic resonance urography (MRU) were performed to confirm the diagnosis of UPJO, evaluate unilateral renal function, and assess the number, size, and location of renal stones (Figure 1). Inclusion criteria were: (I) age under 18 years; (II) confirmed UPJO with ipsilateral renal stones; and (III) undergoing either RALP or LP combined with flexible ureteroscopy. Exclusion criteria included: (I) bilateral UPJO; (II) recurrent UPJO after prior surgery; (III) anatomical anomalies; and (IV) incomplete clinical data. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of the Seventh Medical Center of the Chinese PLA General Hospital (No. S2022-052-01) and informed consent was obtained from the legal guardians of all participants.

Figure 1 CTU images demonstrating UPJO with concurrent renal calculi. (A) Preoperative CTU image showing renal calculi located in the lower calyces of kidney, which are typically more difficult to access and remove. (B) Representative CTU image demonstrating significant hydronephrosis caused by UPJO, with clear dilation of the renal pelvis and calyces. CTU, computed tomography urography; UPJO, ureteropelvic junction obstruction.

Patients were allocated to the RALP or LP groups based on stone characteristics, hydronephrosis grade, and surgeon preference. RALP was preferred for more complex or anteriorly located stones. All surgeries were performed by a single experienced pediatric urologist, who had completed over 100 RALP procedures. Postoperatively, patients underwent IVU, diuretic renogram, and/or ultrasound to evaluate their drainage patterns and assess for residual stones. Successful stone-free outcome was defined as no documented stone fragments on postoperative radiographic imaging (KUB, renal ultrasound and/or CTU) (7). Follow-up with ultrasound, imaging and diuretic renogram was performed at 3, 6, and 12 months postoperatively, and yearly thereafter to confirm procedural success. Success was defined as an improvement in drainage.

Surgical technique

After routine preoperative preparation and anesthesia, pnuemoperitoneum was established and maintained at 6–8 mmHg pressure. All ports were placed under direct vision included one 8.5 mm camera trocar, one 8-mm trocar and one 5-mm trocar. The trocar position has been described in an article previously published by our team (8). For the RALP and LP procedure in renal hydronephrosis, please refer to our previously published articles detailing RALP and LP techniques (8-10). Once the ureteral access sheath is in place, the renal pelvis and calyces can be explored using a flexible ureteroscope. The flexibility of the ureteroscope is particularly beneficial for pediatric cases UPJO with renal calculi, where the stones are generally numerous and small, rarely exceeding 1 cm. The Small stones and fragments can be retrieved using a stone retrieval basket, while tiny stones can be flushed and suctioned out. Larger stones can be fragmented using holmium laser lithotripsy, which is highly effective for breaking them into smaller, easily removable pieces (Figure 2).

Figure 2 Intraoperative view demonstrating the combination of LP and flexible ureteroscopy for intrarenal stone retrieval. LP, laparoscopic pyeloplasty.

In this study, based on RALP for UPJO reconstruction, during the procedure, a small window of approximately 0.2 cm was created at the junction of the renal pelvis and ureter by incising the muscle layer while preserving the integrity of the mucosa. With the precise assistance of robotic arms, the sheath was carefully advanced through the small incision into the renal pelvis (Figure 3). This unique technique not only uses intrarenal fluid for stone fragmentation, eliminating the need for additional irrigation fluid, but also prevents complications such as peritonitis, infection, and paralytic ileus caused by urine leakage. Moreover, it minimizes the risk of further renal pelvis dilation, stone repositioning, renal function impairment, and electrolyte imbalances associated with large volumes of irrigation fluid.

Figure 3 Intraoperative visualization of RALP technique combined with flexible ureteroscopy. Flexible ureteroscopy via 8 or 5 mm (depending on the surgical angle) robotic access sheath. A small window of approximately 0.2 cm was created at the junction of the renal pelvis and ureter by incising the muscle layer while preserving the integrity of the mucosa. RALP, robot-assisted laparoscopic pyeloplasty.

Statistical analysis

Data are presented as mean (range) for continuous variables and frequency (percentage) for categorical variables. Statistical analysis was performed using SPSS version 24.0 software. An unpaired two-tailed Student t-test was used to compare the means between the two groups with normally distributed continuous variables and Mann-Whitney nonparametric test with other continuous variables. Categorical variables were compared using the Chi-squared test or Fisher’s exact test. A P value <0.05 was considered statistically significant.

Results

As shown in Table 1, a total of 25 patients were included in the study: 11 in the RALP group and 14 in the LP group. There were no significant differences between the two groups regarding age (9.0 vs. 8.6 years, P=0.12), gender distribution (6 male, 5 female vs. 9 male, 5 female, P=0.75), or laterality (4 right-sided vs. 6 right-sided, P=0.69). The mean stone size (12.7 vs. 10.6 mm, P=0.09) and the number of stones (3.3 vs. 2.4, P=0.10) were slightly higher in the RALP group, though these differences were not statistically significant.

RALP was associated with a significantly longer operative time (212.7 vs. 185.0 minutes, P=0.03), but resulted in less estimated blood loss (48.2 vs. 60.2 mL, P=0.01). The hospital stay was shorter in the RALP group, though not statistically significant (6.5 vs. 7.7 days, P=0.07). No significant differences were found in complication rates (9.1% vs. 14.3%, P=0.80).

Stone clearance rates were comparable between the two groups (90.9% vs. 85.7%, P=0.25). There were three cases of incomplete stone clearance during the initial surgery. The incomplete clearance was primarily due to the fragmentation of some stones into small pieces, which were easily overlooked or difficult to remove, especially during the flexible ureteroscopy procedure, where small fragments may not be easily detected. For two of these patients, a second-look ureteroscopy was performed to remove the remaining stones. The third patient underwent ESWL to treat small stone fragments. These ancillary procedures successfully cleared the residual stones

All patients were followed up at 1, 3, and 6 months after surgery, and then annually. Three cases of postoperative transient urinary leakage (Clavien Grade IIIa) were observed. One patient was in the RALP group and two patients were in the LP group. The urinary leakage lasted between 5 and 10 days and was managed conservatively with the placement of a double-J stent. The leakage resolved after the stents were removed, and no further complications were reported during follow-up. Both groups achieved 100% stone-free status after ancillary procedures, and the success rate, defined as improvement in drainage, was 100% in both groups.

Discussion

The primary treatment goals for UPJO combined with renal stones are to relieve the obstruction, remove the stones, and ideally complete both tasks in a single procedure without compromising outcomes (11). While open surgery offers a high success rate, it is limited in removing renal pelvic stones and is associated with significant surgical trauma and a prolonged recovery period (12). Both RALP and laparoscopic UPJO repair have shown comparable success rates to open surgery, with the added benefits of minimal invasiveness and faster recovery (13). These techniques allow for enhanced visualization of the obstruction, precise suturing, and the preservation of surrounding vasculature to minimize bleeding and scarring (14). Additionally, simultaneous stone removal under laparoscopy or RALP has been successfully reported in adults, with limited studies in pediatric cases due to small sample sizes (6).

To our knowledge, this is the first comparative analysis using dual endoscopy (LP vs. RALP) in pediatric cases, representing the largest single-center study on this topic. Our results indicate that both RALP and LP are effective for treating UPJO with renal stones. Both groups, using dual endoscopy, maintained the same patient positioning and trocar placement as for hydronephrosis surgery. This did not compromise the efficacy of hydronephrosis treatment but significantly improved the operating angle for ureteroscope manipulation. The ureteroscope could explore all parts of the renal pelvis and calices, reducing the risk of stone residue.

RALP is associated with reduced intraoperative blood loss, shorter hospital stays, and greater ergonomic comfort for the surgeon, although it comes at a significantly higher cost (15). While RALP provides clear clinical benefits, such as reduced blood loss, shorter hospital stays, and improved ergonomics. It incurs significantly higher costs due to the robotic system, maintenance, and consumables. In pediatric settings, where resources may be limited, these expenses can impact the choice of surgical approach. In contrast, LP, while more physically demanding for the surgeon, remains an equally effective and more affordable option (16). Therefore, in cases where financial considerations are paramount, LP offers a viable alternative without compromising surgical outcomes (17).

Neither LP nor RALP is well-suited for comprehensive exploration through the renal pelvis incision. Hidden stones may be missed if not adequately visualized on preoperative imaging or during intraoperative fluoroscopy (1). The placement of LP trocars determines the relative position of the robotic arm and kidney. Despite the robotic arm’s flexibility, certain blind spots in the collecting system may still remain, increasing the risk of residual stones (18,19). Due to the need for renal pelvis and ureter reconstruction, the incision used for stone exploration is often small, which may limit visibility and hinder complete stone removal.

Ureteroscopy, when combined with LP, offers high safety and an increased stone clearance rate. This combined approach leverages the minimally invasive advantages of RALP while maximizing the efficiency of stone removal (1,6). Despite the good flexibility of ureteroscopes, the clearance rate for lower calyx stones remains lower than 10% when the angle less than 30° between the calyx and ureter (20,21). In UPJO cases, where stones predominantly accumulate in the lower pole, both transurethral and simple RALP methods often struggle with incomplete stone removal. The dual endoscopy approach effectively overcomes these limitations by improving the ureteroscope’s angle of approach and allowing full exploration of the renal collecting system.

The most common complication of UPJO surgery is recurrent obstruction, which occurs in approximately 5% of cases, often due to urine extravasation or inflammatory reactions (22,23). Postoperative urinary tract infections may increase the risk of recurrent obstruction, although this study found no cases of recurrence, possibly due to the limited sample size and follow-up duration. In our study, three patients experienced postoperative transient urinary leakage, classified as Clavien-Dindo Grade IIIa complications. This included one case in the RALP group and two cases in the LP group. All cases were successfully managed with the placement of a double-J stent, and the leakage resolved within 5–10 days without further intervention.

There are several limitations in this study. First, the retrospective nature of the analysis inherently carries the risk of selection bias and limits the ability to control for all confounding variables. Second, although our sample size is one of the largest single-center reports on the combination of robotic-assisted LP and ureteroscopy in pediatric patients with UPJO and renal stones, the overall number of cases remains relatively small, potentially limiting the generalizability of the findings. Third, the follow-up period is relatively short, which may underestimate the incidence of long-term complications such as recurrent obstruction or stone recurrence. Furthermore, intraoperative stone exploration was reliant on preoperative imaging and fluoroscopic guidance, which could result in missed stones, particularly in cases with complex collecting system anatomy. Given the single-center and retrospective nature of this study, future multicenter prospective studies with larger sample sizes and longer follow-up periods are warranted to confirm the reproducibility and long-term outcomes of this combined surgical approach. Despite these limitations, our findings highlight the practical advantages of combining minimally invasive pyeloplasty with flexible ureteroscopy. This technique allows for safe and effective management of both UPJO and concomitant renal calculi in a single procedure, offering clear clinical benefits in terms of reduced invasiveness, high stone clearance rates, and efficient recovery. These results can inform surgical decision-making in pediatric patients with complex urinary tract conditions.

Conclusions

This study demonstrates that both RALP and LP combined with flexible ureteroscopy are effective options for managing pediatric UPJO with renal calculi, with each approach offering distinct advantages. RALP offers benefits in terms of reduced blood loss and hospital stay, while LP remains a cost-effective alternative. Further studies with larger samples and longer follow-up are needed to validate these findings.

Acknowledgments

We are grateful to all the pediatric participants and their legal guardians for their voluntary participation in this study.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-557/rc

Data Sharing Statement: Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-557/dss

Peer Review File: Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-557/prf

Funding: This work was supported by the Capital’s Funds for Health Improvement (No. 2022-2-5083), the Youth Support Fund of Chinese PLA General Hospital (No. 22QNFC112), and the Construction Project for High-Level Clinical Specialties in Public Hospitals in Hohhot Capital Region (No. 2024-BFXM-02014).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-2024-557/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of the Seventh Medical Center of the Chinese PLA General Hospital (No. S2022-052-01) and informed consent was obtained from the legal guardians of all participants.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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