4.2 NPIAP Stages 1 through 4

NPIAP Stages 1 through 4

The National Pressure Injury Advisory Panel (NPIAP) staging categories are the clinical classification system used in practice to describe the deepest visible anatomic loss from pressure and/or shear. OpenExamPrep uses those category names because wound teams document with them. Staging describes tissue destruction; it is not by itself a dressing order, and it is never used to reverse-number a healing wound.

A pressure injury is localized damage to the skin and/or underlying tissue, usually over a bony prominence or related to a medical device. Assign a numeric stage only when you can see enough anatomy to do so. If the base is hidden by slough or eschar, that finding belongs in the unstageable category in the next section—not in a guessed Stage 3.

Stage 1: intact skin with non-blanchable color change

Stage 1 is intact skin with a localized area of non-blanchable erythema. On lightly pigmented skin, press and release: redness that blanches then returns is reactive hyperemia, not Stage 1. Non-blanchable redness that persists after pressure is removed is Stage 1 until a better explanation exists.

On darkly pigmented skin, classic red erythema may be absent or hard to see. Look for:

• Color that is darker than, or otherwise different from, adjacent skin and that does not resolve promptly with offloading
• Temperature change (warmer or cooler than nearby skin)
• Firmness, boggy texture, or subtle swelling
• Pain or tenderness the patient can report, or guarding in patients who cannot speak

Stage 1 still has an intact epidermis. Persistent purple, maroon, or deep-red intact skin over a loaded prominence is not Stage 1; that pattern is deep tissue pressure injury (DTPI), taught in the next section. Do not wait for an open wound before you offload a Stage 1 finding.

Stage 2: partial-thickness with exposed dermis

Stage 2 is partial-thickness loss of skin with exposed dermis. The wound bed is viable, pink or red, and moist. It may also present as an intact or ruptured serum-filled blister. Adipose is not visible. Granulation tissue, slough, and eschar are not present. If you see yellow slough, the injury is not Stage 2.

Stage 2 is frequently misused as a wastebasket for any open area. The following are not Stage 2 pressure injuries even when they are partial-thickness:

A blood-filled blister is not the serum-filled blister of Stage 2; suspect DTPI when the history is pressure or shear over a loaded area.

Scenario: the open area that is IAD, not Stage 2

A nurse documents bilateral, irregular, moist, bright-red erosion across the natal cleft and posterior thighs in a patient with liquid stool. There is no single oval over the sacrum. That pattern is incontinence-associated dermatitis, not a Stage 2 pressure injury. Pressure injury and IAD can coexist; when they do, describe both rather than forcing one label.

Stage 3: full-thickness with visible adipose

Stage 3 is full-thickness skin loss. Adipose is visible in the ulcer. Granulation tissue and epibole (rolled wound edges) are often present. Slough and/or eschar may be visible. Undermining and tunneling may occur. Fascia, muscle, tendon, ligament, cartilage, and bone are not exposed. If slough or eschar hides the base so you cannot tell whether those structures are present, the wound is unstageable, not Stage 3 by guesswork.

Depth varies with anatomy. On the bridge of the nose, ear, occiput, and malleolus there is little subcutaneous tissue, so a Stage 3 may be shallow and still be full-thickness. On the buttocks, a Stage 3 may be deep before fascia appears. Depth in millimeters is not the stage.

Stage 4: exposed deeper structures

Stage 4 is full-thickness skin and tissue loss with exposed or directly palpable fascia, muscle, tendon, ligament, cartilage, or bone. Slough and eschar may be present. Epibole, undermining, and tunneling are common. Osteomyelitis is a clinical concern when bone is exposed, but you do not need imaging to assign Stage 4 if the structure is visible or palpable.

The same anatomical caution applies: a shallow wound on the ear or occiput can still be Stage 4 if cartilage or bone is exposed. Do not down-stage a shallow Stage 4 because it does not look deep enough.

Numeric stages at a glance

Never reverse-stage

A healing wound does not move from Stage 4 to Stage 3 to Stage 2 to Stage 1. Once the deepest anatomic loss has been Stage 4, granulation that fills the cavity is still a Stage 4 pressure injury, healing. Closed skin after a Stage 4 is a healed Stage 4, not a Stage 1. Reverse-staging underestimates the original tissue loss and misleads later clinicians about residual dead space and recurrence risk.

If you were never able to see the base, you still do not reverse-stage an unstageable wound into a smaller number because the surface looks smaller. After the base is visible, assign Stage 3 or Stage 4—the true depth—not a lesser stage because the wound is filling.

Anatomical variation: shallow can still be Stage 3 or 4

Sites with scant subcutaneous fat can show Stage 3 or Stage 4 with very little depth:

• Bridge of the nose
• Ear (exposed cartilage is a Stage 4 structure)
• Occiput
• Malleolus

Conversely, the sacrum, buttocks, and heel can hide a large cavity under a modest surface opening. Probe gently per facility protocol when indicated; do not stage from a photograph of the surface alone if undermining is possible.

Pressure injury versus incontinence-associated dermatitis

IAD does not follow a single bony-prominence pattern. A sacral oval with a distinct edge in an immobile patient is the pressure-injury pattern even if the patient is also incontinent.

Scenario: ear cartilage after oxygen tubing

A thin older adult has a shallow ulcer on the helix with visible cartilage after days of unpadded oxygen tubing. Depth is only a few millimeters. This is still Stage 4 if cartilage is exposed, and it is also a medical device-related pressure injury documented with the device. Shallow does not mean Stage 2.