What is the purpose of straining urine during kidney stone management?

• A. To prevent stone formation
• B. To sterilize urine
• C. To capture stones or fragments for composition analysis
• D. To collect urine for testing of infection

Answer: (C)

Capturing stones or fragments for composition analysis is the main purpose of straining urine during stone management. When stones pass or are broken up during treatment, they can be very small and easy to miss without a strainer. Using a fine sieve or strainer in the toilet collects any stone material so the lab can analyze what the stone is made of. Knowing the composition (for example, calcium oxalate, calcium phosphate, uric acid, struvite, or cystine) helps tailor subsequent treatment and prevention strategies, such as dietary adjustments, medications, or metabolic evaluations to reduce the risk of recurrence. This approach isn’t intended to prevent stone formation by itself, nor to sterilize urine or diagnose infection; those goals involve other methods like hydration, separate infection testing, and imaging follow-up.