Pressure Ulcer Staging
On this page
Direct answer
Pressure ulcers (pressure injuries) are localised damage to skin and underlying tissue, usually over a bony prominence, caused by pressure or pressure combined with shear. Staging follows the international NPIAP/EPUAP classification: stage 1 is non-blanchable erythema of intact skin; stage 2 is partial-thickness loss with a viable pink-red wound bed; stage 3 is full-thickness loss with fat visible; stage 4 exposes bone, tendon or muscle; unstageable wounds are hidden by slough or eschar; and deep tissue pressure injury presents as persistent non-blanchable deep discolouration.
What you must remember
- Stage 1: intact skin with non-blanchable redness that does not turn white when pressed; in darker skin, assess temperature and firmness changes instead.
- Stage 2: partial-thickness dermal loss with a shiny pink-red bed, or an intact or ruptured serum-filled blister; no slough or eschar.
- Stage 3: full-thickness loss with subcutaneous fat visible but not bone, tendon or muscle; slough, undermining and tunnelling may be present.
- Stage 4: full-thickness loss with exposed or directly palpable bone, tendon or muscle; risk of osteomyelitis.
- Unstageable: the base is obscured by slough or eschar so depth cannot be judged; stable dry eschar on heels is generally left intact.
- Deep tissue pressure injury: persistent non-blanchable deep red, maroon or purple discolouration indicating deeper damage that may evolve rapidly.
- Risk assessment uses the Braden scale (a score of 18 or below generally indicates risk; lower scores mean higher risk); prevention rests on repositioning at least two-hourly, 30-degree lateral tilts, pressure-redistribution surfaces, heel offloading, skin inspection and nutrition.
Common confusion
Stage 2 is not a blister of any cause — it refers to pressure-related partial-thickness loss, and moisture-associated skin damage around the perineum should not be staged at all. Stages 3 and 4 are separated by whether bone, tendon or muscle is visible or palpable, not by wound size. Reverse staging does not exist: a healing stage 4 ulcer is documented as a healing stage 4, never as a stage 2, because lost muscle and fat are not regenerated.
Exam-focused takeaway
Expect definition-matching on the four stages plus the two special categories, a description asking you to stage, and prevention questions built on the Braden scale and two-hourly repositioning. Remember the commonest sites — sacrum, heels, ischial tuberosities, greater trochanters, occiput, elbows — and the aetiology trio of pressure, shear and friction. The classic trap is calling an eschar-covered wound stage 4 rather than unstageable.
Frequently asked questions
How is a stage 2 pressure ulcer identified?
Partial-thickness skin loss with a viable pink or red bed that may appear as an intact or ruptured serum-filled blister, without slough or eschar.
What distinguishes stage 3 from stage 4?
Stage 3 involves full-thickness loss with fat visible but no exposed bone, tendon or muscle; stage 4 exposes or allows direct palpation of these structures.
Why are some pressure ulcers called unstageable?
Because slough or eschar obscures the base so full thickness cannot be determined; the true stage appears only after debridement.
Which scale is used to assess pressure ulcer risk?
The Braden scale, with 18 or below generally indicating risk; the Norton scale is the older alternative.
How often should at-risk patients be repositioned?
At least every two hours in bed, with heel offloading and 30-degree lateral tilts rather than direct trochanteric positioning.