The following is a list of the four stages of pressure ulcers, otherwise known as decubitus ulcers or bed sores, with a general description of each stage:

Stage I – Non-blanchable redness of intact skin, the heralding lesion of skin ulceration. Discoloration of skin, warmth, edema, indurations or hardness may also be indicators.

Stage II – Partial thickness skin loss involving epidermis, dermis or both. The ulcer is superficial and presents clinically as an abrasion, blister or shallow crater.

Stage III – Full thickness skin loss involving damage to, or necrosis of, subcutaneous tissue that may extend down to, but not through, underlying fascia. The ulcer presents clinically as a deep crater with or without undermining of adjacent tissues.

Stage IV – Full thickness skin loss with extensive destruction, tissue necrosis, or damage to muscle, bone or supporting structures (e.g. tendon, joint capsule). Undermining and sinus tracts also may be associated with Stage IV pressure ulcers.