Which description corresponds to stage 4 pressure ulcer?

• A. Full thickness skin loss with exposed muscle, tendon, or bone
• B. Partial thickness skin loss with exposed dermis
• C. Full thickness skin loss with visible fat
• D. Shallow open ulcer with slough

Answer: (A)

Stage four ulcers show full-thickness tissue loss with exposure of deeper structures. When bone, tendon, or muscle can be seen or palpated, the wound has penetrated through all layers of skin and into underlying tissues. That’s why this description fits stage four—the depth reaches beyond the dermis to structures like muscle or bone.

Understanding the others helps: a partial-thickness loss involves only epidermis and/or dermis (Stage II) and looks like a shallow, red or pink wound. Full-thickness loss with exposed fat is Stage III, where fat is visible but bone, tendon, or muscle are not exposed. A shallow ulcer with slough describes necrotic tissue in a less deep wound and does not indicate exposure of deeper structures, so it does not meet the criteria for stage four. Slough or eschar can be present in advanced ulcers without changing the defining depth criterion that confirms stage four when bone, tendon, or muscle are exposed.