In which condition does edema commonly occur?

Edema commonly occurs in thrombophlebitis, which is an inflammation of a vein associated with the formation of a blood clot. This condition leads to obstruction of venous return from the affected area. As the blood flow is impeded, there is an accumulation of fluid in the surrounding tissues, resulting in swelling or edema. The inflammatory process also contributes to increased permeability of the vessels, allowing more fluid to escape into the interstitial space.

In contrast, dehydration typically leads to a decrease in body fluids, which would not cause edema. Thrombosis may cause localized swelling, but it is primarily the combination of inflammation and restriction of blood flow in thrombophlebitis that most directly leads to the fluid retention seen in edema. While infections can cause localized swelling and may lead to edema due to inflammation, thrombophlebitis is more specifically associated with this fluid accumulation due to its direct impact on venous circulation.