Stage 4 pressure ulcer is defined as?

• A. Full-thickness tissue loss with exposed bone, muscle, or tendon
• B. Partial thickness loss
• C. Skin loss limited to epidermis
• D. Non-viable tissue only

Answer: (A)

Staging pressure ulcers is about how deep the tissue damage goes. The deepest stage is full-thickness loss, meaning all skin layers are destroyed and the wound opens down to deeper structures. The description that matches this level of severity is full-thickness tissue loss with exposed bone, tendon, or muscle. That exposure of underlying structures is what defines this stage, even if slough or eschar is present and there may be undermining or tunneling. In contrast, indications of only partial-thickness loss or skin loss limited to the epidermis describe shallower ulcers, not stage four. Descriptions that mention non-viable tissue often point to wounds where depth is obscured or not yet fully assessable, which isn’t the same as stage four.