Lymphoedema is an accumulation of fluid and waste products which presents as a swelling of the affected part of the body. It can be caused by an inadequate lymph system (primary lymphoedema) or by damage to the lymph system following trauma or surgery, particularly cancer treatment (secondary lymphoedema).

The condition can significantly impair function and mobility, lay the patient open to severe infection, and lead to other associated problems such as muscular skeletal pain, reactive depression and body image problems. Patients often find it difficult to exercise (so weight is frequently an additional problem) and many find they have to modify or reduce their work or give up altogether. Patients treated early and thoroughly are less likely to develop severe (and sometimes irreversible) complications.

Most cases of lymphoedema affect the limbs but the head, face, trunk and genitals can also be involved (midline oedema).