Chronic Venous Insufficiency (CVI) is a medical condition characterized by leg pain and swelling due to damage and blood clots in the venous valves of the veins. The valves in the veins help to prevent the backflow of blood. When they are damaged, blood tends to flow backward due to gravity and accumulate in the veins, especially in the legs. This causes excessive fluids to leak out of the veins, resulting in swollen legs. Over time, symptoms, such as itching and discoloration of the skin on the legs may appear. If left treated, the swelling may cause capillaries in the legs to burst, resulting in reddish-brown colored skin. It may also form ulcers that are difficult to heal. Post-thrombotic or post-phlebitic syndrome is a type of CVI that develops as a complication deep vein thrombosis, a condition that is characterized by blood clots in deep veins.