Wound Type: Pressure Ulcer

What is a pressure ulcer?

A pressure ulcer, or pressure sore, is damage to the skin and underlying tissue, caused when an area of the skin is under pressed.

Pressure ulcers can occur both when the skin is under a large amount of pressure for a short period of time, and when the skin is under a lesser amount of pressure for a longer period of time. Pressure cuts off blood supply to the skin, starving it of oxygen and nutrients, which leads to a breakdown and formation of an ulcer.

Who is at risk of developing a pressure ulcer?

If a person has to stay in a bed or a chair for a long period of time, or has a health condition which limits movement, they have an increased risk of developing a pressure ulcer.

Conditions that disrupt normal blood flow through the body, such as type 2 diabetes, can also put a person at higher risk of developing a pressure ulcer.

The symptoms and development of a pressure ulcer

Healthcare professionals use several grading systems to describe the severity of pressure ulcers. The most common is the European Pressure Ulcer Advisory Panel (EPUAP) grading system. The higher the grade, the more severe the injury to the skin and underlying tissue.

Category 1

  • Intact skin with non-blanchable erythema (i.e. In white skin types, affected skin is red and does not turn white when pressure is applied. In black and brown skin types, affected area is often darker than surrounding area.)
  • Localised area, usually over a bony prominence.
  • The skin remains intact, but it may itch or be painful.
  • Recognising non-blanching erythema at this stage, and acting early can help to halt development into a higher category of pressure ulcer, and prevent further damage.

Category 2

  • Partial thickness skin loss, presenting as a shallow open ulcer, with a red pink wound bed.
  • No slough present
  • May present as an intact or ruptured blister.

Category 3

  • Full thickness skin loss.
  • Subcutaneous fat may be visible.
  • Bone, tendon and muscle not exposed.
  • Slough may be present.
  • Undermining and tunnelling may be present.

Category 4

  • The most severe type of pressure ulcer.
  • Full thickness tissue loss.
  • Bone, tendon and muscle may be exposed.
  • Slough may be present on wound bed.
  • Undermining and tunnelling may be present.
  • People with grade 4 pressure ulcers have a high risk of developing a life-threatening infection.


  • A pressure ulcer is considered unstageable when the wound bed of a full thickness tissue loss ulcer is covered by slough and / or eschar. 
  • Until the slough and/or eschar is derided, the true condition, and depth of the wound cannot be assessed, and therefore cannot be categorised.



Pressure ulcers are a key indicator of the quality and experience of patient care

NHS Improvement

£1.4 million

The daily cost to the NHS for treating pressure ulcers Guest et al, 2017


Guest JF, Ayoub N, McIlwraith T et al (2017) Health economic burden that different wound types impose on the UK’s National Health Service. Int Wound J 14: 322–30 Guest JF, Fuller GW, Vowden P, Vowden KR (2018) Cohort study evaluating pressure ulcer management in clinical practice in the UK following initial presentation in the community: costs and outcomes. BMJ Open 8: e021769