Pressure injuries may be painful but may not be noticed by patients with decreased awareness or sensation. Once a pressure injury is noted on a patient, it is most appropriate to stage the injury for consistent documentation. The National Pressure Injury Advisory Panel (NPIAP) provides a staging system and definitions. Based on the NPIAP definitions, a patient with an injury that has full-thickness loss without exposure of underlying bone or muscle is at which of the following NPIAP stages?