Swelling is due to the accumulation of fluid (edema) in tissues. It occurs when blood pools in the leg veins, increasing pressure in the leg veins and forcing fluids out of the veins into tissues. Blood may pool because the heart cannot pump out all of the blood it receives from the rest of the body (in heart failure) or because a deep vein in the leg is blocked (in deep vein thrombosis).

Swelling in the legs, ankles, and feet or in the abdomen may indicate heart failure or a venous disorder, such as deep vein thrombosis. However, such swelling is most commonly caused by standing or sitting in one position too long or by age-related changes in leg veins. Swelling of the legs is also common during pregnancy. Swelling may also be due to liver or kidney disorders.

If the blood supply is inadequate, the affected part of the body may feel numb.

If the blood supply is inadequate, if anemia is present, or if the veins do not drain adequately, the skin may appear pale or bluish (or purplish).

Last full review/revision April 2006 by Paul H. Tanser, MD