Retrograde Intrarenal Surgery in Patients with Renal Anomalies and Urolithiasis Using an Aspirating Ureteral Access Sheath

Background: Current technological advancements, including the miniaturization of endoscopic instruments and improved image quality, have established retrograde intrarenal surgery (RIRS) as a leading treatment method for patients with kidney stones smaller than 20 mm. In daily practice, we encounter cases that fall outside standard clinical guidelines. Such cases include patients with nephrolithiasis and renal anomalies. The development of small-caliber flexible endoscopes with highly maneuverable distal tip, combined with holmium laser technology, the use of nitinol baskets for stone displacement and extraction, as well as the application of aspirating access sheaths and active irrigation, have made it possible to perform effective and safe endoscopic lithotripsy in patients with renal anomalies.

Objective: To analyze the outcomes of retrograde intrarenal surgery using a holmium laser and an aspirating ureteral access sheath in patients with renal anomalies (complete and incomplete renal duplication, horseshoe kidney, renal ectopia, renal malrotation, polycystic kidney disease) and nephrolithiasis.

Materials and Methods: A retrospective study was conducted at the Regional Clinical Hospital No. 2 and the Scientific Research Institute – Ochapovsky Regional Clinical Hospital No. 1. Between 2022 and 2024, we analyzed the treatment outcomes of 80 patients with urolithiasis and renal anomalies. The study included 30 patients with duplex kidney (18 with incomplete and 12 with complete duplication), 22 with horseshoe kidney, 18 with renal ectopia and malrotation, and 10 with polycystic kidney disease. Ureteral stents were placed in all patients 10–14 days prior to RIRS. Depending on the visual assessment of ureteral diameter, a 10 Ch, 12 Ch or 14 Ch aspirating ureteral access sheath with a flexible distal tip and hydrophilic coating was selected. The advantage of an access sheath with a flexible tip lies in its ability to advance it directly to the lithotripsy site. Laser lithotripsy of stones was performed with active aspiration of fragments. At the end of the procedure, a ureteral stent was placed in all patients. Postoperatively, all patients underwent low-dose CT to assess for residual fragments and determine the need for repeat RIRS. Results: A total of 95 RIRS procedures were performed in 80 patients (38 women and 42 men). The mean age was 40 ± 15 years. The success rate, assessed by the stone-free rate (SFR) on postoperative day 1, was 81.25%. After repeat procedures, this rate increased to 95%. SFR was considered positive for residual fragments smaller than 2 mm. Repeat procedures were performed in 6 patients with duplex kidney (2 with complete and 4 with incomplete duplication), as well as in 5 patients with horseshoe kidney, 3 patients with ectopia and renal malrotation, and 1 patient with polycystic kidney disease. Reinterventions were performed on day 3 after the initial procedure. The following results are presented collectively for all groups. The mean stone size was 11.06 ± 3.98 mm, with a density of 1017 ± 235.8 Hounsfield Units (HU). The mean operative time was 50.4 ± 5 minutes, and the mean hospital stay was 5 ± 1 days. Complications classified as Clavien-Dindo grade I (macrohematuria, pain, fever) occurred in 11.25% of patients, primarily on postoperative days 1–2, and were minor. Grade II complications were observed in 6.25% of patients, including cases of acute pyelonephritis in 3 patients on the first postoperative day and in 2 patients on the second postoperative day, which were successfully managed with antibiotic therapy. One patient with a horseshoe kidney developed urosepsis within 6 hours postoperatively, requiring intensive care and hemoperfusion. The overall complication rate was 18.75%. No Grade III or Grade V complications were reported.

Conclusions: In patients with renal anomalies and urolithiasis, retrograde intrarenal surgery using an aspirating ureteral access sheath is an effective and safe method, characterized by a high SFR and a low complication rate. This method should be considered a firstline treatment option and a viable alternative to extracorporeal shock wave lithotripsy or percutaneous nephrolithotomy. Each case requires an individualized approach to ensure patient safety and achieve optimal outcomes. Further research is needed to optimize surgical techniques and define indications for RIRS in various renal anomalies, as the majority of publications focus on horseshoe kidney.

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