Wound Etiology and Pressure Injury Staging

Staging is the second question. Etiology is the first, and getting it wrong makes everything downstream wrong — the stage, the OASIS item, the plan of care, and the treatment.

Step one: identify the etiology

Before you reach for a staging definition, think it through:

• What caused this?
• How did it get there?
• Consider the mechanism — moisture-associated, venous insufficiency, arterial insufficiency, pressure, shear, trauma
• Take the past medical history into account: diabetes, PAD, PVD, lymphedema

A wound on a heel in a patient with PAD and a wound on a heel in an immobile patient with a Braden score of 12 may look similar and are not the same wound.

Clues that point to pressure

The stages

Stage 1

Intact skin with non-blanchable redness.

• Skin is intact
• Redness does not turn white when pressed
• May be painful, warmer, cooler, firmer, or softer than the surrounding tissue

Key point: no open area is present.

Stage 2

Partial-thickness loss of skin with exposed dermis.

• Shallow, open wound
• Pink or red wound bed
• May appear as an intact or ruptured blister
• No slough or eschar

Key point: epidermis and partial dermis only.

Stage 3

Full-thickness skin loss.

• Fat (adipose tissue) is visible
• Granulation tissue may be present
• Slough may be present
• No exposed muscle, tendon, cartilage, or bone

Key point: subcutaneous tissue is visible.

Stage 4

Full-thickness skin and tissue loss.

• Exposed or directly palpable bone, tendon, muscle, fascia, cartilage, or ligament

Key point: the deepest stage.

Unstageable

Full-thickness skin and tissue loss in which the wound base is obscured.

• Covered by slough and/or eschar
• Depth cannot be determined

Do not remove stable heel eschar solely for staging purposes. Stable, dry, adherent eschar on an ischemic heel is acting as a biological cover. Removing it to satisfy a documentation field can cost the patient the limb.

Deep Tissue Injury

Persistent non-blanchable deep red, maroon, or purple discoloration.

• Skin may be intact or non-intact
• Dark purple or maroon appearance
• May evolve rapidly into a deeper wound

Key point: usually caused by intense pressure and shear.

Wounds that must NOT be staged

Staging language belongs to pressure injuries only. Do not stage:

• Venous ulcers
• Arterial ulcers
• Diabetic ulcers
• Surgical wounds
• Skin tears
• Traumatic wounds
• Burns
• Moisture-associated skin damage (MASD)
• Incontinence-associated dermatitis (IAD)

These are documented by depth and tissue type — partial thickness or full thickness, wound bed description, exudate, periwound condition, measurements — not by stage.

Calling a diabetic foot ulcer a "Stage 3" is one of the most common charting errors in home health, and it misroutes the whole plan of care.

A grafted or flapped pressure ulcer is no longer a pressure ulcer

Pressure ulcers that have been closed with a skin graft or a muscle, advancement, or rotational flap are captured as surgical wounds — not as pressure ulcers.

Once the surgeon has closed it, the wound you are looking at is the surgical repair. Report it as a surgical wound and stop reporting it as a pressure injury.

Getting this wrong double-counts the patient: the same wound appears as both a pressure ulcer and a surgical wound, which misstates the pressure injury data the agency is measured on and confuses the plan of care.

The same applies to total surgical excision of pressure ulcer damage. See Is It a Surgical Wound? (M1340 / M1040).

The weekly wound worksheet

The first visit of the week — typically Monday or Tuesday — includes photographs and measurements of every wound.

• Treatment orders live in the patient's goals. If there are none, notify the RN Case Manager so they can be added, and check the referral if needed.
• Add wound education every visit — signs and symptoms of infection, incision care, pressure, diabetes, whatever fits the patient. Always end with the patient or caregiver voicing understanding.
• If you are teaching a patient or caregiver to perform the care, chart a successful return demonstration before discharge.

If you do not know how to perform a treatment — Unna boot, 2- or 4-layer compression, wound VAC — ask. Someone will be sent to assist or teach you. Nobody expects you to work it out on a patient.

What every wound photo must show

A photograph without these four is not usable evidence — it could be any wound, on any patient, on any day.

• The patient's name
• The date the photo was taken
• The location of the wound
• The measurement

Get them into the frame — a label or card beside the wound is the usual way — so the photo carries its own identification and cannot be separated from it.

How to measure, so two clinicians get the same number

Measurements are only useful if they are comparable week to week. That needs a fixed convention, not each clinician's own.

Length is always measured head to toe. Along the axis of the body, from the patient's head toward their feet — regardless of how the wound is shaped or which way it looks longest. Width is then measured across that, side to side.

If you measure the longest dimension instead, a wound that has not changed at all will appear to grow and shrink as different people visit.

Tunnelling and undermining are measured by the clock, with the patient's head as 12 o'clock for that area of the body. Record the depth and the position together:

Tunnelling 2.4 cm at 7 o'clock. Undermining 1.1 cm from 3 to 5 o'clock.

Orient the clock to the patient, not to the wound and not to where you happen to be standing. A wound on the lateral calf and a wound on the sacrum both use the same reference: the head is 12.

Measuring depth when you cannot see the base

Some wounds have no measurable depth because the base is obscured. That is a finding, not a gap.

Record the depth as 0 and state the reason.

Depth 0 — unable to measure, wound base obscured by eschar.

Never leave depth blank, and never estimate a depth you did not measure. A blank field reads as an omission; 0 with a stated reason reads as an assessment.

The same applies to any wound whose base you cannot visualise — eschar, slough covering the bed, or a dressing a physician has ordered not to be removed. Say which it is.

A wound obscured by eschar or slough is also, for pressure injuries, Unstageable — and remember not to remove stable heel eschar just to get a measurement or a stage.

Before you document

• Etiology determined, and consistent with the history
• Measurements: length head-to-toe × width × depth, plus tunnelling and undermining by clock position, head = 12
• Depth recorded as 0 with a stated reason where the base cannot be seen
• Photograph taken on the first visit of the week, showing name, date, location, and measurement
• Wound bed: granulation, slough, eschar, epithelial — with percentages
• Exudate: amount, colour, odour
• Periwound: intact, macerated, erythematous, indurated
• Pain
• Staging applied only if this is a pressure injury
• Matched to the correct OASIS item — see Is It a Surgical Wound?