Outcomes of ureteroscopy for stone disease in anomalous kidneys: a systematic review

Introduction: Treatment of stone disease in anomalous kidneys can be challenging. As ureteroscopy (URS) has advanced, the number of studies reporting on outcomes of URS for stone disease in anomalous kidneys has increased. Our objective was to perform a systematic review of the literature to evaluate the outcomes of URS for stone disease in this group of patients. Methods: A Cochrane style review was performed in accordance with the PRISMA guidelines using Medline, EMBASE, CINAHL, Cochrane Library, Scopus and individual urologic journals for all English language articles between inception and June 2018. Results: Fourteen papers (413 patients) with a mean age of 43 years and a male to female ratio of 285:128 were included. The underlying renal anomaly was horseshoe kidney (n = 204), ectopic kidney (n = 117), malrotation (n = 86), cross fused ectopia (n = 2) and others (n = 2). With a mean stone size of 16 mm (range 2–35 mm), the majority of stones were in the lower pole (n = 143, 34.6%) or renal pelvis (n = 128, 31.0%), with 18.9% (n = 78) having stones in multiple locations. Treatment modality included the use of flexible ureteroscope in 90% of patients and ureteral access sheath used in 11 studies. With a mean operative time of 61.3 min (range 14–185 min), the initial and final SFR was 76.6% (n = 322) and 82.3% (n = 340), respectively. The overall complication rate was 17.2% (n = 71), of which 14.8% were Clavien I/II and the remaining 2.4% were Clavien ≥ III complications. Conclusion: Although ureteroscopy in patients with anomalous kidneys can be technically challenging, advancements in endourological techniques have made it a safe and effective procedure. In these patients the stone-free rates are good with a low risk of major complications.