| Stage 1: nonblanchable erythema of intact skin | Intact skin with nonblanchable redness of a localized area usually over a boney prominence; darkly pigmented skin may not have visible blanching, its color may differ from the surrounding area; area may be painful, firm, soft, warmer, or cooler compared with adjacent tissue; stage I may be difficult to detect in patients with dark skin tones; may indicate “at-risk” persons | |
| Stage 2: partial-thickness skin loss with exposed dermis | Partial-thickness loss of skin or tissue presenting as a shallow open ulcer with a red-pink wound bed, without slough; may present as an intact or open/ruptured serum-filled or serosanguineous blister; presents as a shiny or dry, shallow ulcer without slough or bruising*; this category should not be used to describe skin tears, tape burns, incontinence-associated dermatitis, maceration, or excoriation | |
| Stage 3: full-thickness skin loss | Full-thickness skin loss; subcutaneous fat may be visible but bone, tendon, or muscle is not exposed; slough may be present but does not obscure the depth of tissue loss; may include undermining and tunneling; depth of ulcer varies by anatomic location; bridge of the nose, ear, occiput, and malleolus do not have (adipose) subcutaneous tissue and ulcers can be shallow; in contrast, areas of significant adiposity can develop extremely deep ulcers; bone/tendon is not visible or directly palpable | |
| Stage 4: full-thickness skin and tissue loss | Full-thickness tissue loss with exposed bone, tendon, or muscle; slough or eschar may be present; often includes undermining and tunneling; depth of ulcer varies by anatomic location; bridge of the nose, ear, occiput, and malleolus do not have (adipose) subcutaneous tissue and ulcers can be shallow; ulcers can extend into muscle or supporting structures (e.g., fascia, tendon, joint capsule), making osteomyelitis or osteitis likely to occur; exposed bone/muscle is visible or directly palpable | |
| Additional categories/stages for the United States | |
| Unstageable pressure injury: obscured full-thickness skin and tissue loss | Full-thickness tissue loss in which actual depth of ulcer is completely obscured by slough (yellow, tan, gray, green, or brown) or eschar (tan, brown, or black) in the wound bed; until enough slough or eschar is removed to expose the base of the wound, the true depth cannot be determined, but it will be stage 3 or 4; stable (dry, adherent, intact without erythema or fluctuance) eschar on the heels serves as a natural (biological) cover and should not be removed |
| Deep-tissue pressure injury: persistent non-blanchable deep red, maroon or purple discoloration | Purple or maroon localized area of discolored intact skin or blood-filled blister caused by damage to underlying soft tissue from pressure or shear; area may be preceded by tissue that is painful, firm, mushy, boggy, warmer, or cooler compared with adjacent tissue; deep-tissue injury may be difficult to detect in patients with dark skin tones; evolution may include a thin blister over a dark wound bed; wound may further evolve and become covered by thin eschar; evolution may be rapid, exposing additional layers of tissue even with optimal treatment |
