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# Pressure injury staging

- Assessment

Pressure injuries are staged by the depth of visible damage, from intact red skin to exposed bone.

Updated Nov 5, 2026

## Key points

- Stage 1: intact skin with redness that does not blanch when pressed.
- Stage 2: partial-thickness skin loss with exposed dermis, or an intact or ruptured blister of clear fluid; fat is not visible.
- Stage 3: full-thickness tissue loss with visible fat; no cartilage, tendon, ligament, muscle or bone exposed.
- Stage 4: full-thickness tissue loss with cartilage, tendon, ligament, muscle or bone exposed.
- Unstageable: the wound bed is covered by slough or eschar. Deep tissue: dark red, maroon or purple colour that does not blanch.
- Device-related injury: staged with the same stages; mucosal membrane injury: not staged.

## What it is

The staging system of the NPIAP (National Pressure Injury Advisory Panel, then called NPUAP), revised in 2016 and also used by the international guideline with EPUAP, describes four stages by the depth of tissue damage, plus two categories: unstageable injury, when the wound bed cannot be seen, and deep tissue injury. It also names two special situations: medical device-related injury, which is staged with the same system, and mucosal membrane injury, which cannot be staged with it. The revision separated stage 2 from moisture-associated skin damage. Because the level of damage can worsen, the injury is reassessed continually.

## Reference values

- The stage is set by the deepest tissue damage that can be seen.
- It is used for injuries caused by pressure, or pressure combined with shear.
- Moisture-associated skin damage is not a stage 2 pressure injury.
- Persistent deep red, maroon or purple discoloration that does not blanch is classified as deep tissue injury.
- The most common sites are the sacrum, heels, ischial tuberosities and coccyx.
- Stable, dry eschar on a heel or an ischaemic limb is not softened or removed.

## What you need

- Good lighting.
- Gloves and a disposable measuring tool.
- A comfortable position that lets you see the whole area, with help if needed.
- The institutional wound record.
- Knowing how the patient's skin looks elsewhere, because discoloration may look different in darkly pigmented skin.

## How to measure it (and why)

- Explain what you will do, protect the patient's privacy and clean your hands: the assessment exposes intimate areas.
- Position the patient to see the area well and compare with nearby healthy skin: in dark skin, changes may look different.
- On intact red skin, press gently and release: if it does not blanch, it is at least stage 1.
- Look at the colour: persistent deep red, maroon or purple suggests deep tissue injury, which can evolve rapidly.
- On open skin, identify the deepest tissue visible (dermis, fat, muscle, bone): that defines the stage.
- If slough or eschar covers the wound bed, classify it as unstageable: the true depth cannot be known.
- If the injury is under a device, record it as device-related and assign the stage; if it is on a mucous membrane, do not stage it.
- Record location, bed, size (head-to-toe length by width, and depth), exudate, edges, surrounding skin, infection signs and pain: so it can be compared.

## Pressure injury categories (NPIAP, in our own words)

| Category | What you see | Key to telling it apart |
| --- | --- | --- |
| Stage 1 | Intact skin with localised redness that does not blanch | Purple or maroon tones point to deep tissue injury instead |
| Stage 2 | Partial-thickness skin loss with exposed dermis; pink or red, moist bed; or a clear fluid blister | Fat is not visible |
| Stage 3 | Full-thickness tissue loss with visible fat; slough or eschar may be present | No cartilage, tendon, ligament, muscle or bone exposed |
| Stage 4 | Full-thickness tissue loss with deep structures exposed | Cartilage, tendon, ligament, muscle or bone can be seen |
| Unstageable | Full-thickness loss with the bed covered by slough or eschar | Removing the dead tissue would likely reveal a stage 3 or 4 |
| Deep tissue injury | Dark red, maroon or purple area that does not blanch, or a blood-filled blister | May evolve rapidly or resolve without tissue loss |
| Device-related | Injury under a medical device (tube, mask, splint) | Staged with the same stages |
| Mucosal membrane | Injury on a mucous membrane where a device was in place (mouth, nose, urethra) | Not staged: the skin staging system does not apply to mucosa |

## How to read it

- A new stage 1 or deep tissue injury means the prevention plan needs review at once.
- Removing slough or eschar usually reveals a stage 3 or 4 injury; the true stage is set then.
- Staging helps communicate precisely and measure the quality of care.
- Wounds of vascular, traumatic, neuropathic or dermatological origin are not called deep tissue injury.

## Next step: when to call for help

- Tell the nurse in charge when you find a new injury of any stage, so the prevention plan is adjusted and the injury is reported.
- Report early if you see a purple or maroon area: deep tissue injury can evolve rapidly.
- Tell the doctor if there are new signs of infection: redness, hardened tissue, swelling, pus (yellow or green drainage), odour or increasing pain.
- Report slough or eschar, tunnelling or undermining, or exposed bone or tendon, so wound management can be assessed.
- Report if the measurements show that the injury is not healing over successive assessments.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the difference between a stage 2 and a stage 3 pressure injury?

In stage 2 the skin loss is partial and the dermis is visible; in stage 3 the loss is full-thickness and subcutaneous fat is visible.

## When is a pressure injury classified as unstageable?

When there is full-thickness tissue loss but the bed is covered by slough or eschar, so its true depth cannot be seen.

## What does an area of intact maroon or purple skin that does not blanch suggest?

A deep tissue pressure injury. It can evolve rapidly, so prevention is stepped up and it is reported.

## How are medical device-related injuries and mucosal membrane injuries classified?

A device-related injury on skin is staged with the same stages; an injury on a mucous membrane is not staged.

## What is done with stable, dry eschar on a heel?

It is not softened or removed. The injury is recorded as unstageable and reported for assessment.

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## Connections

## Related 2

- [Preventing pressure injuries: risk scales, repositioning and skin care](https://durgical.com/en/nursing/preventing-pressure-injuries-risk-scales-repositioning-and-skin-care/)
- [Wound assessment: bed, edges, exudate and signs of infection](https://durgical.com/en/nursing/wound-assessment-bed-edges-exudate-and-signs-of-infection/)

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Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.

Sources: [Nursing Fundamentals, 10.4 Pressure Injuries](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Fundamentals_(OpenRN)/10%3A_Integumentary/10.04%3A_Pressure_Injuries) (Open RN, Wisconsin Technical College System (CC BY 4.0), LibreTexts edition, 2021); [Nursing Skills, 20.3 Assessing Wounds](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/20%3A_Wound_Care/20.03%3A_Assessing_Wounds) (Open RN, Wisconsin Technical College System (CC BY 4.0), LibreTexts edition, 2021); [Revised National Pressure Ulcer Advisory Panel Pressure Injury Staging System](https://pmc.ncbi.nlm.nih.gov/articles/PMC5098472/) (Journal of Wound, Ostomy and Continence Nursing (PubMed Central), 2016); [Prevention and Treatment of Pressure Ulcers/Injuries: Clinical Practice Guideline (International Guideline)](https://www.epuap.org/pu-guidelines/) (EPUAP, NPIAP and PPPIA, 2019).

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Source: https://durgical.com/en/nursing/pressure-injury-staging/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/nursing/pressure-injury-staging/