Nurse cutting away dead tissue from a bedsore on an elderly patient's heel. A bedsore (also called a decubitus ulcer or pressure sore) is an ulcerated area of skin caused by irritation and continuous pressure on a part of the body. Bedridden, elderly patients (especially those unconscious) are particulary vulnerable. Healing is hampered by a reduced blood supply and diligent nursing care (cleansing & repositioning) is needed to prevent local gangrene occurring.