Category/Stage 4
![stage 4](https://academy2.activheal.com/wp-content/uploads/2024/04/stage-4.png)
![](https://academy2.activheal.com/wp-content/uploads/2024/04/exposed-bone.png)
Category/Stage 4: Full-thickness tissue loss with exposed bone, tendon or muscle
Slough or eschar may be present. Often includes undermining and tunnelling. The depth of a category/stage 4 pressure ulcer varies by anatomical location. The bridge of the nose, ear, occiput and malleolus do not have (adipose) subcutaneous tissue, and these ulcers can be shallow. Category/stage 4 ulcers can extend into muscle and/or supporting structures (e.g. fascia, tendon, or joint capsule), making osteomyelitis or osteitis likely to occur. Exposed bone/muscle is visible or directly palpable
The EPUAP/NPIAP/PPPIA (2019) has added two new categories to describe previously upgradeable pressure ulcers.