Which factor best explains edema development in obesity-related lower-extremity venous ulcers?

• A. Excessive edema that increases tissue tension
• B. Decreased arterial flow
• C. Increased capillary perfusion
• D. Reduced interstitial pressure

Answer: (A)

In obesity-related lower-extremity venous ulcers, edema develops primarily because venous hypertension from impaired venous return leads to fluid leaking into the interstitial space. The resulting excessive interstitial fluid increases tissue tension, creating a mechanically stressed environment that compresses small vessels and impairs microcirculation. This reduced perfusion and oxygen delivery promote skin breakdown and delay healing of ulcers.

This concept fits best because the edema itself is the driving factor for tissue tension and microvascular compromise, which are central to ulcer formation in this setting. Not arterial flow reduction, which would cause ischemia from the arteries; not increased capillary perfusion, which would not explain edema formation; and not reduced interstitial pressure, which would not account for fluid buildup. Clinical management often targets decreasing edema and tissue tension, for example with compression therapy and leg elevation, to improve venous return and healing.