The term chronic oedema acts as an umbrella description of abnormal swelling of tissues which lasts for more than 3 months, regardless of whether the aetiology is lymphatic or venous in origin. There are a number of causes of chronic oedema, including dependency oedema, that is to say oedema associated with inactivity and immobility, venous oedema (swelling mainly caused by the vascular insufficiency) and lymphoedema, a chronic swelling due to lymphatic failure.