In a morbidly obese patient with lower-extremity edema, which mechanism best explains the development of edema and risk for venous stasis ulcers?

• A. Impedance of normal arterial blood flow to the lower legs secondary to obesity
• B. Callus buildup due to sustained pressure secondary to obesity
• C. Poor hygiene due to limited ability to perform self-care secondary to obesity
• D. Excessive edema that accumulates in the lower legs secondary to obesity

Answer: (D)

Edema in the legs from morbid obesity arises mainly because excess body weight and reduced mobility impair venous return, increasing venous pressure in the lower extremities. This elevated hydrostatic pressure pushes fluid from the capillaries into the interstitial spaces, leading to fluid accumulation (edema). Over time, the persistent edema lowers tissue oxygenation and impairs nutrient delivery, making the skin and underlying tissues more susceptible to breakdown and developing venous stasis ulcers. So describing excessive edema accumulating in the lower legs due to obesity directly reflects the mechanism driving both the swelling and the risk for ulcers.

Arterial flow impairment would present differently, often with pain, pallor, diminished pulses, or cooler limbs and does not explain edema as the primary issue. Callus formation is a skin change from pressure/friction, not edema. Poor hygiene affects wound care but does not explain why edema and venous ulcers develop.