Percutaneous management of calculi within horseshoe kidneys

Purpose: Percutaneous treatment of patients with calculi in a horseshoe kidney can be challenging due to the altered anatomical relationship in the retroperitoneum. Therefore, we performed a multi-institutional review to assess the safety and efficacy of this minimally invasive technique. Materials and Methods: Of 37 patients identified with calculi in a horseshoe kidney at 3 institutions 24 (65%) underwent percutaneous nephrolithotripsy as primary treatment. Average patient age was 48.4 years and 75% of the patients were male. In 3 patients with staghorn calculi mean stone size as measured by computed digitized stone surface area was 448 mm². Mean followup was 5.8 months. The stone-free rate, complication rate, need for secondary intervention and stone composition were evaluated. Results: Renal access was obtained through an upper pole calix in 63% of the cases, a lower calix in 25% and a middle calix in 4%. Access location was not documented in 1 patient (4%). Of the 24 patients 21 (87.5%) were rendered stone-free after primary or second look procedures. Flexible nephroscopy was used in 84% of cases. Minor complications occurred in 4 patients (16.7%), whereas 3 (12.5%) experienced major complications, including significant bleeding necessitating early cessation, nephropleural fistula and pneumothorax. No deaths occurred as a result of this treatment choice. Stone analysis was available for 21 cases (87.5%). Calcium stones predominated (87.5%), followed by uric acid (9.5%) and struvite (4.8%). Conclusions: Percutaneous treatment of patients with renal calculi in a horseshoe kidney is technically challenging, usually requiring upper pole access and flexible nephroscopy due to the altered anatomical relationships of the fused renal units. The success rate based on stone-free results and a relatively low incidence of major complications suggest that this minimally invasive management option is an effective means of stone management in this complex patient population.