Stages of Pressure Ulcers
Pressure ulcers are classified into four distinct stages (Stage 1 through Stage 4) based on the depth of tissue damage, plus two additional categories: unstageable and deep tissue injury.
Standard Staging System
The staging system categorizes pressure ulcers by the anatomical depth of tissue loss 1:
Stage 1: Non-Blanchable Erythema
- Intact skin with localized area of non-blanchable redness
- Usually over a bony prominence
- The area may be painful, firm, soft, warmer, or cooler compared to adjacent tissue
- May be difficult to detect in darkly pigmented skin
Stage 2: Partial-Thickness Skin Loss
- Partial-thickness loss of dermis
- Presents as a shallow open ulcer with a red-pink wound bed
- May also present as an intact or ruptured serum-filled blister
- No slough or bruising present
Stage 3: Full-Thickness Skin Loss
- Full-thickness tissue loss
- Subcutaneous fat may be visible, but bone, tendon, or muscle are not exposed
- Slough may be present but does not obscure the depth of tissue loss
- May include undermining and tunneling
- Depth varies by anatomical location (minimal tissue in areas like the bridge of the nose or ear; very deep in heavily adipose areas)
Stage 4: Full-Thickness Tissue Loss
- Full-thickness tissue loss with exposed bone, tendon, or muscle
- Slough or eschar may be present
- Often includes undermining and tunneling
- Depth varies by anatomical location
- Can extend into muscle and/or supporting structures (fascia, tendon, joint capsule)
- High risk for osteomyelitis and septic arthritis
Additional Categories
Unstageable: Depth Unknown
- Full-thickness tissue loss where the base of the ulcer is covered by slough (yellow, tan, gray, green, or brown) and/or eschar (tan, brown, or black) in the wound bed
- Cannot determine true depth until sufficient slough and/or eschar is removed to expose the base of the wound
Deep Tissue Injury (DTI)
- Purple or maroon localized area of discolored intact skin or blood-filled blister
- Results from damage of underlying soft tissue from pressure and/or shear
- The area may be preceded by tissue that is painful, firm, mushy, boggy, warmer, or cooler compared to adjacent tissue
- May be difficult to detect in individuals with dark skin tones
- Can evolve rapidly to reveal the actual extent of tissue injury or may resolve without tissue loss
Critical Clinical Points
Common pitfall: Do not stage moisture-associated skin damage (such as incontinence-associated dermatitis) as a pressure ulcer—these are fundamentally different conditions requiring different management 2.
Anatomical considerations: The depth and severity of pressure ulcers vary significantly by location. Ulcers over areas with minimal subcutaneous tissue (occiput, ear, malleolus, sacrum) may be shallow even at Stage 3, while those in heavily adipose areas (buttocks, trochanter) can be extremely deep 1.
Documentation essentials: For each ulcer, document size, location, stage, presence of eschar and granulation tissue, exudate characteristics, odor, sinus tracts, undermining, and signs of infection 3. This is critical for tracking progression and treatment response.
Mortality impact: Between 1990 and 2001, pressure ulcers were listed as the underlying cause of death in over 21,000 persons in the United States, with treatment costs ranging from $37,800 to $70,000 per case 1. Proper staging directly impacts treatment decisions and outcomes.