How is an unstageable pressure ulcer defined?

An unstageable pressure ulcer is characterized by full thickness tissue loss that is concealed by slough (a type of dead tissue) or eschar (a dry, dark scab or falling away of dead skin). The presence of slough or eschar means that the depth of the ulcer cannot be determined because these materials obscure the underlying tissue. This classification is critical because it indicates that a more severe level of tissue damage is present but cannot be accurately assessed due to the covering material.

In contrast, nonblanchable redness on intact skin reflects a less severe stage that denotes potential skin damage but does not involve tissue loss. Exposed bone, muscle, or tendon signifies a more advanced pressure ulcer stage where deeper structures are visible, but this does not fit the definition of unstageable since it indicates a clear view of tissue damage. Lastly, a fleshy pink base with a break in skin integrity describes a situation where tissue loss is visible, indicating a stage where assessment is possible, rather than being unstageable. Thus, the correct answer captures an essential aspect of pressure ulcer assessment in clinical contexts.