[Retrograde endoscopic treatment of stones in horseshoe kidney].

Introduction: Horseshoe kidney is often associated with ureteropelvic junction obstruction and nephrolithiasis. Retrograde intrarenal surgery (RIRS) is becoming one of the main treatment options for large stones in such patients.

Aim: To study the results of RIRS in patients with horseshoe kidney.

Materials and methods: Between November 2016 and April 2021, 12 patients with stones in horseshoe kidney underwent RIRS in our clinic. There were 9 men and 3 women. The average age of the patients was 44.5+/-12.0 years, the size of the stone was 1.6 cm. In 9 patients, a solitary pelvic stone with a size of up to 2.0 cm was diagnosed, while in the remaining cases pelvic and lower calyx stones were found. In 7 (58.3%) patents, the stone was localized on the right, in 5 (41.7%) on the left side. Two patients had previously undergone unsuccessful percutaneous nephrolithotomy due to the impossibility of puncture of the collecting system. In addition, one patient underwent extracorporeal shock-wave lithotripsy. In all cases, RIRS was performed 2 weeks after ureteral prestenting. After removing the endoscope, a ureteral access sheath was insereted along the guidewire. A flexible ureteroscope was advanced into the collecting system, and an inspection was performed. When a stone was localized in the lower calyx, a Dormia basket was used to relocate it into the pelvis for more convenient lithotripsy and to avoid trauma to the distal part of the endoscope. Due to poor passage of fragments in horseshoe kidney, they were removed as much as possible after lithotripsy and a ureteral stent was put.

Results: In all cases, RIRS with laser lithotripsy was done. The average operation time was 75+/-28 minutes. There were no intraoperative complications; postoperative fever was observed in 2 (16.7%) cases. After lithotripsy, all fragments were removed in 9 (75.0%) patients. In 3 (25.0%) patients, residual fragments were found. Repeated RIRS was performed in two cases; one patient refused repeat procedure. The efficiency of RIRS in patients with horseshoe kidney after two sessions was 91.7%.

Conclusion: Flexible RIRS with laser lithotripsy allows to remove stones in horseshoe kidney with high efficiency and a minimal rate of complications.