5.1 Wound Classification & Staging
Key Takeaways
- Pressure injuries are staged 1-4 by depth of visible tissue loss; Unstageable wounds are obscured by slough or eschar, and a Deep Tissue Pressure Injury (DTPI) presents as intact or non-intact maroon or purple non-blanchable discoloration.
- The Wagner classification grades diabetic foot ulcers 0 through 5, where Grade 0 is intact at-risk skin and Grade 5 is gangrene of the whole foot requiring amputation referral.
- Arterial ulcers sit on distal toes and bony prominences with punched-out edges, pale dry beds, severe pain, diminished pulses, and an Ankle-Brachial Index (ABI) below 0.9.
- Venous ulcers appear in the medial gaiter area with irregular borders, heavy drainage, hemosiderin staining, and pulses that are usually present.
- A Braden Scale score of 18 or lower flags the patient as at risk for pressure injury and should trigger turning schedules and support-surface upgrades within the plan of care.
Why Wound Staging Matters For The PTA
The Physical Therapist (PT) performs the initial wound evaluation, sets the wound diagnosis, and writes the plan of care. The Physical Therapist Assistant (PTA) then implements positioning, off-loading, dressing changes, and exercise inside that plan and reports any change in wound status back to the supervising PT. The PTA does not assign or change a wound stage, debride sharply, or alter the diagnosis.
On the National Physical Therapy Examination for Physical Therapist Assistants (NPTE-PTA) — a 200-item, four-section, four-hour exam scored on a 200-800 scale with a criterion-referenced passing score of 600 — Integumentary items typically fall in the 3-8 question range, and most turn on recognizing a stage, grade, or ulcer pattern from a short scenario, then choosing the correct scope-appropriate action.
Pressure Injury Stages
The National Pressure Injury Advisory Panel (NPIAP) 2019 staging system describes how deep the visible tissue damage goes. A key rule: a stage never "reverses" with healing — a healing Stage 4 is documented as a healing Stage 4, never re-staged downward to a Stage 2. The PTA memorizes the picture, not the management latitude.
| Stage | Skin Integrity | Depth | PTA Picture |
|---|---|---|---|
| Stage 1 | Intact | Non-blanchable erythema | Warm, painful red area over a bony prominence that does not blanch when pressed |
| Stage 2 | Broken | Partial-thickness dermal loss | Shallow open ulcer or intact serum-filled blister; pink-red moist base, no slough |
| Stage 3 | Broken | Full-thickness skin loss | Subcutaneous fat visible; possible slough, undermining, tunneling; no exposed muscle or bone |
| Stage 4 | Broken | Full-thickness with exposed structure | Visible muscle, tendon, ligament, cartilage, or bone; often slough or eschar at edges |
| Unstageable | Broken | Depth obscured | Slough or eschar covers the base; once cleared it will reveal a Stage 3 or 4 |
| Deep Tissue Pressure Injury (DTPI) | Intact or non-intact | Suspected deep damage | Persistent non-blanchable deep red, maroon, or purple discoloration, or a blood-filled blister, over a bony prominence |
Two NPIAP terms commonly tested as distractors: a Medical Device-Related Pressure Injury conforms to the shape of the device (tubing, mask, brace), and a Mucosal Membrane Pressure Injury (on mucous membranes such as the mouth or urethra) cannot be staged with this depth system at all because mucosa lacks the tissue layers the staging scale relies on.
A frequent stem trap is the difference between a Stage 1 injury and a Deep Tissue Pressure Injury: both can present over intact skin, but Stage 1 erythema is superficial and non-blanchable, whereas a DTPI is a deep maroon or purple discoloration signaling damage at the bone-muscle interface that may evolve rapidly into a full-thickness wound. Pain and a temperature change (warm then cool) frequently precede the visible color change, so the PTA who palpates a boggy, warm, discolored heel should treat it as a developing serious injury, off-load it immediately, and report it — not dismiss it as a bruise.
Wagner Classification For Diabetic Foot Ulcers
When a stem mentions a person with diabetes and a plantar or toe lesion, expect Wagner grading rather than NPIAP staging.
- Grade 0 — Intact skin on a high-risk foot (callus, deformity, prior ulcer)
- Grade 1 — Superficial ulcer, no subcutaneous involvement
- Grade 2 — Deeper ulcer into tendon, capsule, or bone but no abscess or osteomyelitis
- Grade 3 — Deep ulcer with abscess, osteomyelitis, or joint sepsis
- Grade 4 — Localized gangrene (forefoot or heel)
- Grade 5 — Gangrene of the whole foot; surgical/amputation referral, PTA defers further local interventions
Differentiating Lower-Extremity Ulcers
Most NPTE-PTA wound items hinge on telling three lower-extremity ulcers apart. The trap is mixing one venous feature into an otherwise arterial picture — read every cue in the stem.
| Feature | Arterial | Venous | Neuropathic (Diabetic) |
|---|---|---|---|
| Typical location | Distal toes, lateral malleolus, dorsum of foot | Medial gaiter region above the medial malleolus | Plantar surface under metatarsal heads or great toe |
| Wound bed | Pale, dry, punched-out edges | Ruddy red, irregular, wet | Pale or pink, often with surrounding callus |
| Pain | Severe; worse with elevation, relieved by dangling | Mild ache; relieved by elevation | Often painless from neuropathy |
| Pulses | Diminished or absent | Usually present | Variable; check carefully |
| Ankle-Brachial Index (ABI) | Below 0.9 = arterial disease | Usually normal | May be falsely elevated above 1.3 from vessel calcification |
| Edema | Minimal | Significant, pitting | Usually localized |
A scope reminder: the PTA does not interpret a new ABI to set the diagnosis, but should know that an ABI below 0.5 contraindicates compression and that any unexpected reading must be reported to the supervising PT before progressing the intervention. The ABI is the ankle systolic pressure divided by the brachial systolic pressure; a value of 0.9 to 1.3 is roughly normal, 0.5 to 0.9 indicates mild-to-moderate arterial disease, and below 0.5 indicates severe ischemia.
Positioning advice follows directly from the ulcer type the candidate identifies: an arterial wound benefits from a dependent (gravity-assisted perfusion) position and is harmed by aggressive elevation or high compression, whereas a venous wound benefits from elevation and graduated compression to fight back-pressure. Choosing elevation for an arterial ulcer, or heavy compression for an ischemic limb, is the wrong-answer pattern the exam loves to insert into an otherwise correct-sounding option.
Braden Scale Risk Triage
The Braden Scale scores six factors — sensory perception, moisture, activity, mobility, nutrition, and friction/shear — for a total of 6 to 23, where lower scores mean higher risk. A score of 18 or lower indicates the patient is at risk for pressure injury and should trigger a turning schedule (commonly every two hours in bed, every 15 minutes in a wheelchair if able to shift independently) plus an appropriate pressure-redistributing support surface. PTAs cite this score to justify position changes, off-loading, and caregiver education within the plan of care, and document the score whenever risk status appears to change.
A PTA is treating a patient with a previously documented Stage 2 sacral pressure injury. During today's session, the PTA notes that the wound bed is now covered by 80% adherent yellow slough, and depth cannot be visualized. What is the most appropriate next action?
Which set of findings is most consistent with an arterial lower-extremity ulcer rather than a venous ulcer?