To detect casts more easily in urine sediment, which microscopic method is used?

• A. Fluorescent microscopy
• B. Phase-contrast microscopy
• C. Polarized microscopy
• D. Brightfield microscopy

Answer: (B)

Phase-contrast microscopy is used because casts are colorless and have only small differences in refractive index compared with urine. This method converts those subtle phase differences into visible brightness, producing bright outlines and internal details that make casts stand out without staining. That enhanced contrast lets you see different types of casts—hyaline, granular, waxy, and others—more clearly in urine sediment.

Brightfield can show casts but often them appear faint; polarized microscopy highlights crystals based on birefringence rather than general cast visibility; fluorescent microscopy requires specific staining or autofluorescence and isn’t routine for detecting casts.