Pressure injury (pressure ulcer) !
A pressure injury is skin and tissue damage from staying too long in one position, usually over bony areas. It is largely preventable with good nursing care.
Updated 2026-11-01
Structures involved
Tap one to see what it is and open it in 3D.
In the clinical exam
Why it happens
- Hypoxia, ischemia and reperfusion injury
- Patterns of necrosis: coagulative, liquefactive, caseous, fat, fibrinoid, gangrenous
- Healing of skin wounds: first and second intention
- Abnormal repair: chronic wounds, hypertrophic scar, keloid, contracture
- Granulation tissue and scar formation
- What delays healing: infection, diabetes, nutrition, glucocorticoids, poor blood flow
What it is
Localised damage to the skin and underlying soft tissue, usually over a bony prominence or under a medical device, caused by sustained pressure, often combined with shear. It may present as intact skin or an open ulcer.
Who gets it
Common in hospitals, intensive care units, nursing homes and among people cared for at home in bed. Older adults with frailty, dementia, hip fracture or stroke and people with spinal cord injury are most affected. It is used as a quality-of-care indicator, and most cases are preventable.
Causes
- Sustained pressure that compresses capillaries between bone and a surface
- Shear (sliding down in bed or a chair) and friction
- Moisture from incontinence, sweat or wound drainage that softens the skin
- Medical devices (tubes, masks, splints, catheters) pressing on the skin
Risk factors
- Immobility: bedridden, wheelchair users, sedation, paralysis
- Reduced sensation (spinal cord injury, stroke, diabetic neuropathy)
- Advanced age and frailty, thin fragile skin
- Urinary or faecal incontinence
- Malnutrition, low protein intake and dehydration
- Poor perfusion: shock, peripheral artery disease, diabetes, anaemia
- Cognitive impairment (dementia, delirium)
Pathophysiology
Pressure above capillary closing pressure for a prolonged time causes ischaemia, then reperfusion injury and tissue death. Muscle and fat tolerate ischaemia worse than skin, so damage often starts deep near the bone and the visible wound underestimates it. Shear stretches and kinks vessels, and moisture weakens the epidermis.
Classification
- Stage 1: intact skin with non-blanchable redness (may look darker or purplish in darker skin)
- Stage 2: partial-thickness skin loss with exposed dermis; shallow open ulcer or intact blister
- Stage 3: full-thickness skin loss; fat visible, may have slough, undermining or tunnelling; no bone, tendon or muscle exposed
- Stage 4: full-thickness skin and tissue loss with exposed bone, tendon, muscle or cartilage
- Unstageable: base obscured by slough or eschar
- Deep tissue pressure injury: persistent deep red, maroon or purple discoloration or blood-filled blister
- Also: medical device-related and mucosal membrane pressure injuries
Symptoms and signs
- Red skin that does not blanch when pressed, over the sacrum, coccyx, heels, ischial tuberosities, greater trochanters, elbows or occiput
- Changes in temperature, firmness or texture of the skin over a bony area
- Pain or tenderness (may be absent if sensation is reduced)
- Blister, shallow crater or deep wound, sometimes with slough or black eschar
- Drainage or odour if infected
Diagnosis
- Clinical
- Head-to-toe skin assessment on admission and regularly afterwards, with attention to bony prominences and skin under devices. Risk is scored with a validated tool such as the Braden scale (sensory perception, moisture, activity, mobility, nutrition, friction and shear; a lower score means higher risk). The wound is staged and its size, depth, tunnelling, base tissue, exudate and edges are documented.
- Tests
- Nutritional markers and blood count; wound tissue culture or bone biopsy when infection or osteomyelitis is suspected; blood glucose in diabetes.
- Imaging
- MRI when osteomyelitis under a deep ulcer is suspected; plain X-ray is less sensitive. Ankle-brachial index or Doppler when arterial disease is suspected (e.g. heel ulcers).
Differential diagnosis
- Incontinence-associated dermatitis (moisture damage, diffuse and superficial, not over a bony prominence)
- Venous ulcer
- Arterial (ischaemic) ulcer
- Diabetic neuropathic foot ulcer
- Skin tear or burn
Goal of treatment
Prevent new injuries, relieve pressure, keep the wound clean and moist enough to heal, treat infection, and correct underlying factors such as malnutrition and incontinence.
Treatment
- Conservative
- Pressure relief is the foundation: scheduled repositioning (typically about every 2 hours in bed), 30-degree lateral tilt, keeping the head of the bed as low as is safe to limit shear, floating the heels off the bed and using pressure-redistributing mattresses and cushions; never massaging reddened bony areas.
- Conservative
- Skin care: gentle cleansing, barrier products and prompt management of incontinence to keep skin dry; lifting rather than dragging the patient.
- Lifestyle
- Nutrition and hydration with adequate calories and protein, guided by a dietitian.
- Procedure
- Wound care: cleansing, removal of dead tissue (debridement) and dressings that keep a moist wound bed; stable dry heel eschar is often left intact.
- Medical
- Systemic antibiotics for cellulitis, osteomyelitis or sepsis; pain control before dressing changes.
- Surgical
- Surgical debridement and flap reconstruction for selected stage 3 and 4 injuries.
- Follow-up
- Nursing reassessment of risk score and skin at every shift or as protocol requires, wound measurements, and documentation of progress.
Complications
- Cellulitis and sepsis
- Osteomyelitis of the underlying bone (e.g. sacrum, calcaneus)
- Abscess, sinus tracts and septic arthritis
- Pain, longer hospital stay and loss of function
- Squamous cell carcinoma in a chronic non-healing wound (rare)
Prognosis
Stage 1 and 2 injuries usually heal in days to weeks once pressure is removed; stage 3 and 4 injuries heal slowly over months, recur often and are linked to higher mortality, mainly reflecting the patient's overall frailty.
Prevention
- Risk assessment (e.g. Braden scale) on admission and regularly
- Regular repositioning and pressure-redistributing support surfaces
- Keeping skin clean and dry and managing incontinence
- Adequate nutrition and hydration and early mobilisation
- Checking skin under medical devices
Test yourself
Think of the answer, then tap the question to see it.
What defines a stage 1 pressure injury?
Intact skin with localised non-blanchable redness over a pressure point.
Which six areas does the Braden scale assess?
Sensory perception, moisture, activity, mobility, nutrition, and friction and shear; a lower total means higher risk.
What is the most common site of pressure injury in a bedridden patient lying supine?
The sacrum and coccyx, followed by the heels.
When is a pressure injury classified as unstageable?
When slough or eschar covers the wound base so its true depth cannot be seen.
What is a key nursing intervention for preventing pressure injuries in an immobile patient?
Scheduled repositioning, typically about every 2 hours, with pressure-redistributing surfaces and heels floated off the bed.
Related conditions
- Osteomyelitis
- Sepsis and septic shock
- Spinal cord injury
- Femoral Neck Fracture
- Alzheimer disease
- Ischaemic stroke
- Diabetic foot
- Venous leg ulcer
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Pressure Sores (MedlinePlus, US National Library of Medicine, 2026); Preventing pressure injuries (MedlinePlus, US National Library of Medicine, 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.
