What is a pressure ulcer (pressure injury)?
A pressure injury (older names: pressure ulcer, bedsore, decubitus ulcer) is a localised injury to skin and soft tissue that develops from prolonged pressure over a bony prominence, often in patients with limited mobility. The terminology moved from 'ulcer' to 'injury' because the damage can be present before the skin breaks: stage 1 lesions and deep tissue injury have intact skin, so 'ulcer' under-describes them.
Three factors decide whether tissue is damaged: the intensity of pressure, its duration, and the tolerance of the tissue (skin and deeper structures) to that load. When external force exceeds the capillary filling pressure, the microcirculation is occluded, producing ischaemia and metabolic derangement. Friction and shear add to the damage, and a brief relief of pressure can trigger reperfusion injury, an inflammatory burst of free radicals that deepens the injury.
How are pressure injuries staged (stages 1 to 4)?
The staging system used worldwide (NPIAP/EPUAP) classifies a pressure injury by the deepest tissue involved.
| Stage | Skin and tissue involved | Key identifying features |
|---|---|---|
| Stage 1 | Intact skin | Localised non-blanchable erythema; in dark skin there may be no visible blanching, only a change in colour, warmth, firmness or pain |
| Stage 2 | Partial-thickness skin loss (epidermis and/or dermis) | Shallow open ulcer with a red-pink wound bed, or an intact or ruptured serum-filled blister; no necrotic tissue, heals by epithelialisation |
| Stage 3 | Full-thickness skin loss | Fat (subcutaneous tissue) visible; muscle, tendon and bone not exposed; slough or eschar may be present; tunnelling and undermining possible |
| Stage 4 | Full-thickness skin and tissue loss | Exposed or directly palpable muscle, tendon, ligament or bone; slough or eschar; osteomyelitis can follow |
| Unstageable | Full-thickness loss, base hidden | Wound base covered by slough or eschar, so depth cannot be judged until it is removed |
| Deep tissue pressure injury (DTPI) | Intact or non-intact skin over deeper damage | Persistent deep red, maroon or purple discolouration, or a blood-filled blister |
Two additional descriptors are also recognised: medical device-related pressure injury (the lesion takes the shape of the device, and is staged with the same system) and pressure injury of mucous membranes, which occurs on moist membranes.
What can be mistaken for a pressure injury?
Stage 2 has a clear definition that excludes several look-alikes. Moisture-associated skin damage (incontinence-associated dermatitis, intertriginous dermatitis), injury from medical adhesives and traumatic wounds such as skin tears, burns and abrasions are not stage 2 pressure injuries. A true stage 2 has no necrotic tissue and no bruising.
| Condition | How it differs from a pressure injury |
|---|---|
| Diabetic ulcer | Occurs on the foot in a patient with diabetes, usually with neuropathy |
| Venous ulcer | Lower leg, associated with venous disease rather than pressure over a bony prominence |
| Arterial ulcer | Associated with peripheral arterial disease and reduced pulses |
| Pyoderma gangrenosum | Inflammatory ulcer not tied to a pressure point |
| Calciphylaxis | Ischaemic skin necrosis from vascular calcification |
| Incontinence-associated dermatitis | A moisture-associated skin damage, excluded from stage 2 |
| Kennedy terminal ulcer | Named in the literature as a look-alike that needs separate evaluation |
Where do pressure injuries occur and who is at risk?
In adults the commonest sites are the sacro-coccygeal region and the heels (supine or seated position), followed by the ischial tuberosities in people who sit for long periods. They can also occur at the occiput, scapula, elbow, lateral malleolus, shoulder and ear. In bedridden infants the occiput is the commonest site, followed by the sacrum and heels, and device-related injuries of the ears and nose are common in children.
| Type | Examples |
|---|---|
| Mechanical (extrinsic) | Prolonged pressure, shear (sliding down the bed), friction, moisture, medical devices |
| Mobility and sensation | Spinal cord injury, stroke, sedation, dementia, coma, long surgery |
| Nutrition and tissue | Malnutrition, anaemia, low albumin states, advanced age |
| Perfusion | Peripheral vascular disease, diabetes, endothelial dysfunction |
In a review of studies of older people in institutions cited in the 2025 paper, the most common stages were stage 1 and 2, and the calcaneal and sacral regions were the most frequently affected.
What is the Braden scale and how is it scored?
Risk assessment scales such as Waterlow, Norton and Braden are used to flag patients who need prevention. The Braden scale (Bergstrom, 1987) is the most commonly used. It scores six elements; a lower score means higher risk.
| Subscale | Score range | Meaning of the lowest score |
|---|---|---|
| Sensory perception | 1 to 4 | Completely limited |
| Moisture | 1 to 4 | Constantly moist |
| Activity | 1 to 4 | Bedfast |
| Mobility | 1 to 4 | Completely immobile |
| Nutrition | 1 to 4 | Very poor |
| Friction and shear | 1 to 3 | Problem |
| Total score | Risk |
|---|---|
| 15 to 18 | Mild |
| 13 to 14 | Moderate |
| 10 to 12 | High |
| 9 or less | Very high |
How are pressure injuries prevented?
Prevention is the most important part of management. The aim is to maintain tissue integrity and offload vulnerable areas through skin care, hydration and nutrition, avoidance of both maceration and excessive dryness, and pressure-redistributing support surfaces (mattresses and cushions) chosen according to risk, mobility, comfort and the need for microclimate control.
- Repositioning: turning every 4 hours on a viscoelastic foam surface produced fewer pressure ulcers than turning every 2 hours on a standard mattress.
- Support surfaces: pressure-dispersion cushions and mattresses, selected by risk level, ulcer stage, mobility, comfort and need for microclimate control.
- Skin care: diligent skin care, avoiding both maceration and excess dryness.
- Nutrition and hydration: supplements for patients with insufficient intake.
- Sleep: adequate sleep is also part of the prevention bundle.
How is an established pressure ulcer managed?
Once an ulcer has developed, the principles are: offload the area, keep a moisture-balanced wound bed, debride devitalised tissue, and give optimal local and systemic care. Matching treatment to the stage and the wound's features is the exam approach.
| Problem | Approach |
|---|---|
| Offloading | Pressure-redistributing surfaces, repositioning, avoid lying on the wound |
| Dressing choice | Per NPIAP guidance, a silicone foam dressing for a non-infected, moisture-balanced pressure injury; alginate, silver, honey or foam if exudate or infection |
| Necrotic tissue | Surgical, mechanical or enzymatic debridement; mechanical debridement is not for dry eschar |
| Stable dry heel eschar | If there is no infection or underlying ischaemia, leave it intact as a biological protective barrier |
| Infection | Topical antibiotics for local infection; oral antibiotics when spread is systemic |
| Large chronic wound | Negative pressure wound therapy; flap reconstruction to fill dead space in a selected clean, well-granulated wound |
Surgical reconstruction (skin graft, myocutaneous, fasciocutaneous or free flap) suits an uninfected wound with a well-granulated base and good vascular supply in a region protected from soiling. It requires control of comorbidities and adequate nutrition, because the same conditions that caused the ulcer can impede healing of the repair. For perineal injuries, urinary and faecal diversion may be needed to protect the wound.
What are the common exam traps in pressure ulcer staging?
- Stage 1 has intact skin — non-blanchable redness. If it blanches, it is not stage 1.
- Stage 3 shows fat; stage 4 shows muscle, tendon, ligament or bone. Bone or tendon exposure always means stage 4.
- Slough or eschar over the base = unstageable, not stage 3.
- Purple or maroon intact skin = DTPI, which may evolve to a deeper wound.
- Blisters can be stage 2 (serum-filled) or DTPI (blood-filled).
- Moisture damage, skin tears and burns are not pressure injuries.
- Braden: lower = worse. Friction and shear is scored 1 to 3; every other subscale 1 to 4.
- Heel eschar that is stable, dry and uninfected is left alone.