Category/Stage 4

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.