Name four sterilization methods used for different instrument loads.

• A. Steam (autoclave), Dry heat, Ethylene oxide gas, Hydrogen peroxide plasma/low-temperature sterilization.
• B. UV light, Boiling water, Alcohol immersion, Freezer storage.
• C. Gamma irradiation, Autoclave, Steam, Air drying.
• D. Microwave sterilization, Steam, Dry ice, Ethanol soak.

Answer: (A)

Sterilization methods are chosen based on what the instrument load can tolerate and how deeply sterility must be achieved. Steam sterilization uses moist heat under pressure, which penetrates wraps and provides rapid, reliable sterility for most metal instruments and wrapped sets. Dry heat sterilization uses hot, dry air and is best for items that can be damaged by moisture or oils, though it requires higher temperatures and longer cycles. Ethylene oxide gas offers a low‑temperature option for heat‑ and moisture‑sensitive devices, such as plastics and lumened instruments, but it needs careful aeration to remove toxic residues. Hydrogen peroxide plasma provides another fast, low‑temperature method for delicate equipment, with minimal residue and good compatibility with sensitive items.

Other methods listed in less typical contexts don’t reliably sterilize complex instrument loads in standard practice: UV light is mainly surface disinfection and limited by line‑of‑sight access; boiling water and alcohol immersion are disinfection, not sterilization; freezer storage preserves rather than sterilizes; gamma irradiation is used in manufacturing or specialized facilities, not routine in-hospital processing.