Table 1.

Pressure ulcer stages and attendant dangers.  

Stage	Description/dangers
Stage I	Intact skin with nonblanchable redness of a localized area usually over a bony prominence.  The area may be painful, firm, soft, warmer, or cooler compared to adjacent tissue.  May indicate persons at risk of ulcer progression
Stage II	Partial-thickness loss of dermis presenting as a shallow open ulcer with a red-pink wound bed, without slough (necrotic tissue).  May also present as intact or open serum filled blister.  May progress to stage III if pressure is not relieved
Stage III	Full-thickness tissue loss.  Subcutaneous fat may be visible, but bone, tendon, and muscle are not exposed.  Slough may be present but does not obscure the depth of tissue loss.  May include undermining or tunneling.  May progress to stage IV if pressure to wound area is not relieved
Stage IV	Full-thickness tissue loss with exposed bone, tendon, or muscle.  Slough may be present on some parts of the wound bed.  Often include undermining and tunneling.  Osteomyelitis (infection of the bone) may develop in wounds with exposed bone

Source: National Pressure Ulcer Advisory Panel (NPUAP).