Robot-assisted pyeloplasty in children: feasibility and safety of magnetic-end and standard double-J ureteral stent insertion.

Introduction: The need for drainage and the choice of drain in pyeloplasty are still debated. The most popular method at present is the double-J ureteral stent (DJUS), but this requires general anaesthesia (GA) for its removal. To avoid this, magnetic-end double-J ureteral stent (MEDJUS - Magnetic Black-Star®) has recently been developed. The present study reports the feasibility and safety of magnetic-end and standard double-J ureteral stent insertion and removal during robot-assisted pyeloplasty in children.

Methods: We retrospectively analysed the clinical data of patients who underwent robot-assisted laparoscopic pyeloplasty (RALP) and who have had an attempt to insert MEDJUS or DJUS in our department from January 2015 to April 2024. The variables evaluated included the chosen drainage method (DJUS, Magnetic Black-Star® "S"-7 French magnet or "XS"-4.8 French magnet), the technical difficulty related with stent insertion or removal, intra- and postoperative complications and the clinical and radiological outcomes of the procedure.

Results: Between 2015 and 2024, a total of 91 patients (46 girls, 45 boys) underwent RALP with an attempt to insert either a MEDJUS or DJUS. Median age was 9.2 years (1.5-17.7), median weight 31.9 kg (9.5-71). MEDJUS stent was attempted in 29 patients. The insertion success rate was 51.8 % (n = 15). Separately, the Magnetic Black-Star® S and XS insertion success rates were 37.5 % and 69.2 %, respectively. The rate of office removal was 93.3 % (n = 14/15). The only identified risk factor for failure was younger age, in the MEDJUS XS sub-group only. Seventy patients benefited from an attempt to implant DJUS. The insertion success rate was 92.8 % (n = 65). It would appear that the DJUS failures occurred in younger children of lower weight (median age 7.08 years (1.56-11.5); median weight 25 kg (9.5-52)); however, these results were not statistically significant. There was a statistically significant difference between the insertion rate of DJUS and MEDJUS XS (p = 0.0119).

Conclusion: Anterograde insertion of DJUS is a safe and feasible drainage method for RALP in children. MEDJUS avoids the further need for general anaesthesia. However, its anterograde insertion, although feasible, has a high failure rate (48 %). For the time being, its use seems to be limited to the Black-Star® XS magnetic stent, whose results are better, and for older patients. Even so, the failure rate remains high (30 %) and significantly higher than that of the DJUS, despite the equivalent size of the magnet and probe.