The swollen legs and ankles are also known as edema. They are caused by fluid retention in the tissue spaces which is between the body cells. There are many reasons which can be behind the swelling in the legs and ankles.
The degree of edema which is present in the legs and ankles is dependent on the ability of the heart to pump blood, whether the person may be standing or sitting. Standing or sitting for long periods can cause the gravitational force to act on the body. Thus the heart needs to pump more blood in order to compensate for the blood which is flowing to the legs. In case heart fails to pump out more blood, you will observe swollen legs and ankles.
Cirrhosis can be another cause of swollen legs and ankles. Cirrhosis of liver refers to a condition in which the kidney tends to retain salts and water, leading to their accumulation in the tissues which are beneath the skin of the legs and ankles. This leads to the swelling of legs as well as ankles.
People who suffer from kidney problems may also experience edema. In case the kidney fails to function properly, salts get retained in the body leading to retaining water. It is this excess water retention which causes swollen legs and ankles.
Lymphedema refers to swelling in legs in which any one of the legs will be swollen. It is due to a blockage in the lymphatic system, which causes retention of the lymphatic fluid in the legs. This kind of a swelling in legs and ankles which is due to lymphedema can range from mild to extreme.
There are some chronic lung diseases such as bronchitis or chronic obstructive pulmonary disease which may cause swelling in the legs and ankles. It is due to the restricted flow of blood in the vessels of the lungs.