Chronic venous insufficiency (CVI) is poor return of blood from feet and legs back to the heart. CVI may occur following excessive clotting and inflammation of the leg veins, a disease known as deep vein thrombosis. CVI also results from a simple failure of the valves in leg veins to hold blood against gravity, leading to sluggish movement of blood out of the veins, resulting in swollen legs. CVI may cause feet and calves to become swollen, often accompanied by a dull ache made worse with prolonged standing. If CVI is allowed to progress, the skin tends to darken and ulcers may occur. CVI often causes varicose veins.

Health care practitioners typically advise patients to elevate the legs frequently, avoid prolonged standing or sitting, and wear graduated compression stockings with supportive shoes. Recurrent ulceration may be surgically treated with skin grafts. Surgical repair or bypass of the affected veins is sometimes necessary.

People affected by chronic venous insufficiency should not sit or stand for long periods of time. When sitting, they should elevate their legs. Walking helps move blood out of the veins. Wearing tight-fitting compression stockings available from pharmacies further supports the veins.