Which statement is NOT listed as an effect of diathermy on blood and fluid dynamics?

• A. Increase blood flow
• B. Increase capillary pressure
• C. Increase nerve conduction
• D. Increase fibroblast activity

Answer: (C)

When diathermy heats tissue, the immediate changes are driven by the thermal effect on circulation and tissue metabolism. Heating causes arteriolar dilation, which increases blood flow to the treated area and can raise capillary pressure due to greater inflow and the altered hydrostatic forces in the microcirculation. The heightened temperature also boosts cellular activity, so fibroblast activity can increase, supporting tissue repair. Nerve conduction, however, is a neural response to heating rather than a direct change in blood or interstitial fluid dynamics. Temperature can raise nerve conduction velocity, but that effect lies in neural function, not in the blood/fluid–movement changes produced by diathermy. Therefore, the statement about increasing nerve conduction is not a blood and fluid dynamic effect, making it the best answer in this context.