Non-thermal ultrasound effects include which of the following?

• A. Increased cellular activity
• B. Enhanced muscle strength
• C. Pain relief and wound healing
• D. Decreased blood flow

Answer: (C)

Non-thermal ultrasound works through mechanical interactions at low intensity rather than by heating tissue. When delivered in pulsed mode, the energy causes phenomena like stable cavitation and acoustic streaming, which increase movement of fluids and ions at the cellular level. This mechanical stimulation enhances cell membrane permeability and triggers cellular processes involved in healing, including fibroblast activity, collagen synthesis, angiogenesis, and epithelial cell migration. The net clinical effects are analgesia and accelerated tissue repair, making this modality useful for acute injuries and wounds without relying on heat.

Other options don’t fit as well because increasing muscle strength isn’t a direct non-thermal outcome of ultrasound, and decreasing blood flow would counter the healing process ultrasound aims to support by improving microcirculation and tissue repair.