Which therapy is least likely to control edema effectively?

Heat therapy is least likely to effectively control edema because its primary function is to increase blood flow and relax muscles rather than promote fluid reabsorption or movement out of the interstitial spaces. When heat is applied to an area with edema, it causes vasodilation, which can lead to more fluid leaking out of blood vessels into the surrounding tissue, potentially worsening the swelling.

In contrast, compression therapy aids in reducing edema by applying external pressure to the affected area, helping to move excess fluid back into the vascular system. Electrical stimulation can improve circulation and potentially assist in lymphatic drainage, while ultrasound therapy can penetrate tissues and promote healing, which may indirectly help manage edema. Each of these methods has mechanisms that are more aligned with effectively controlling swelling, making heat therapy the least suitable option for this purpose.