inflammation of the femoral vein, the principal vein of the thigh, with formation of a clot that blocks the channel of the vein. The condition may occur shortly after childbirth, or it may result from the use of oral contraceptives. Other predisposing factors are aging, malignancy, and chronic infection. The leg becomes swollen and is pale and painful (hence the name phlegmasia alba dolens—“white, painful inflammation”). If the blockage persists, ulcers may develop. The affected person is kept in bed, with the swollen leg elevated and motionless; anticoagulants are used to prevent further clotting while the body's plasmin (also called fibrinolysin) dissolves the blockage, and antibiotics are used to combat any infection. The leg is bandaged to prevent collection of fluid in the tissues (edema). Severe occlusion may require surgical treatment. If the clot detaches there is danger of pulmonary artery blockage.