| Stage | Description |
| 1 | Skin intact but with non-blanchable redness for >1 hour after relief of pressure. |
| 2 | Blister or other break in the dermis with partial thickness loss of dermis, with or without infection. |
| 3 | Full-thickness tissue loss. Subcutaneous fat may be visible; destruction extends into muscle with or without infection. Undermining and tunneling may be present. |
| 4 | Full-thickness skin loss with involvement of bone, tendon, or joint, with or without infection. Often includes undermining and tunneling. |
| Unstageable | Full-thickness tissue loss in which the base of the ulcer is covered by slough and/or eschar in the wound bed. |
| Deep tissue pressure injury | Purple or maroon localized area of discolored intact skin or blood-filled blister due to damage of underlying tissue from pressure and/or shear. |
