Task: Answer Verification
Input (English): Question: Does the presence of horseshoe kidney affect the outcome of percutaneous nephrolithotomy?
Answer: PNL is the treatment of choice for large and/or complex stones. The presence of a horseshoe kidney does not affect the outcome of PNL. Upper pole access is usually preferred, and flexible nephroscopy is essential to maximize stone-free rates. SA and metabolic data support the premise that calculus formation is a metabolic event.
Output (English): no