What Is A Pressure Ulcer?

  • Helen Maginnis MBChB, BSc. (MedSci) Genetics, University of Glasgow

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Pressure ulcers, also commonly known as bedsores or pressure injuries, are a common issue most often affecting the elderly or the debilitated.1 But what exactly are they? 

A pressure ulcer is an injury to an area of skin and its underlying tissue that results from the application of pressure and a reduction in blood supply to that area (NICE).2 It’s important to treat pressure ulcers quickly to avoid complications, or better still, to prevent them before they occur.2

In this article, we’ll explore how pressure ulcers form, who is most at risk of developing them, how to treat existing ulcers, and how to prevent new ones from forming. 

What is a pressure ulcer and how does one form? 

A pressure ulcer, also referred to as a bedsore, pressure sore, pressure injury or decubitus ulcer, results when the application of pressure causes localised damage to an area of skin and underlying tissue.1,2 Pressure ulcers most commonly form over bony prominences, such are around the hips, sacrum, heels and ankles.1 Babies and children can also develop pressure ulcers, most commonly on the back of the head.3 But, the most commonly affected individuals remain those who are elderly, chronically bedridden or severely debilitated.1,10

The formation of a pressure ulcer is a complex process involving the following crucial components:


Most often, it is a person’s own body weight that applies pressure onto an area of skin and soft tissue, usually between a bony area (like a heel) and an external surface (like a mattress).3 A medical device can also be the source of external pressure that leads to ulcer development.3 Sustained application of pressure means that blood carrying oxygen and nutrients cannot reach the affected area. Over time, this causes some of the affected tissue to die in a process called necrosis.3

Shear and friction

Shear forces and friction exacerbate the above problems. For example, when you are sitting up in bed, you are prevented from sliding down by the friction between your back and your pillow. However, the tissues under your skin will still be pulled down somewhat due to gravity. The resultant shearing forces(forces of layers against one another), caused by skin and tissue moving in opposite directions, can cause associated blood vessels to become twisted or compressed. These changes further reduce the supply of oxygen and nutrients to the area.3


Continuous or abnormal exposure to moisture from sweat or other body fluids can cause the skin to soften and become more vulnerable to breaking down.3

Risk factors for pressure ulcers

Anyone can develop a pressure ulcer, but some people are more at risk than others. 

Older age

Pressure ulcers are most common in people over the age of 70, with two-thirds of cases occurring in this age group.1 Older individuals generally have thinner skin than younger individuals which cannot cope with pressure and friction as relisiliently. They may are also more likely to experience additional risk factors such as reduced mobility and malnutrition which predisposes them to the formation of pressure ulcers.3

Reduced mobility

Reduced mobility makes it harder for an individual, to reposition themselves and reduce pressure on vulnerable areas.1

Sensory impairment

People with sensory impairments, for example as the result of a spinal cord injury or neurological condition, are at increased risk of pressure sores.3 Ordinarily, prolonged pressure on an area of the body produces an uncomfortable sensation which prompts a person to reposition. However, in nervous system disorders where sensation is reduced or absent, a person will not be aware of the discomfort and sustained pressure will continue.1

Chronic medical conditions

Certain medical conditions such as diabetes and cardiovascular disease predispose a person to pressure ulcers.4


Malnutrition increases the risk of pressure ulcers due to an increased predisposition to debilitating diseases and also makes it more difficult for wounds to heal.5

Preventing pressure ulcers

The first step in preventing pressure ulcers is having an understanding of which groups/individuals are most at risk of developing these ulcers. Ensuring your skin is well cared for is crucial, as well as ensuring pressure-relieving devices (such as mattresses and cushions) are made available to those who need them.1 People with reduced mobility and/or sensation should be repositioned regularly.2 For those who are incontinent, special attention should be paid to personal care to reduce the impact of moisture on pressure ulcer risk.Barrier creams may help protect vulnerable areas on the skin from moisture.2 

Grading pressure ulcers

Pressure ulcers can be graded using the International NPUAP/EUPUAP pressure ulcer classification system, which includes the following categories6:

  • Stage I - Non-blanchable erythema: An area of redness that doesn’t turn white when you press it. Note, that stage I ulcers can be more difficult to detect in those with darker skin tones
  • Stage II - Partial thickness skin loss: The ulcer will look shiny or dry. Some loss of skin has occurred, but there is no bruising or slough (soft, moist dead tissue that is usually pale in colour)
  • Stage III - Full-thickness skin loss: Fat may be visible beneath, but muscle and bone will not be. Slough may be present
  • Stage IV - Full thickness tissue loss: All the covering skin and tissue has been lost, exposing bone, tendon or muscle. Dry, dark-coloured dead tissue (eschar) may be visible in the wound
  • Unstageable: Full-thickness tissue loss has occurred, but the base of the wound is covered by slough or eschar, meaning that the full depth cannot be determined
  • Suspected deep tissue injury (depth unknown): These injuries will present as purple or maroon-coloured areas of intact skin, or as blood blisters. They result from damage to underlying tissue as a result of pressure and/or shear. These wounds may be more difficult to detect in people with darker skin tones

Treating pressure ulcers

If a pressure ulcer has formed, grading it can help guide treatment. Managing an ulcer involves the following principles1:

Reducing pressure on the ulcer

Reducing pressure on pressure ulcers is essential. There are various aids that can help with this, such as pressure-relieving mattresses and cushions.2 Your healthcare team will be able to advise on what items are best suited to your case. People who require support with repositioning should have this provided every six hours at a minimum.2

Treating the ulcer

Dressings will be applied regularly to help your pressure ulcer heal.2 If very regular dressing changes are required, for example from a very moist or leaky ulcer, then you may be offered negative pressure wound therapy which can aid healing.2,7 

Deep or complex ulcers (usually stage III or IV) may require surgical debridement to remove excess dead tissue or debris.1,2 For less severe ulcers, autolytic debridement may be used. This process involves the application of special dressings which allow for the body’s natural enzymes to break down dead tissue.2,8

If there is evidence that the ulcer is infected, then you will be offered antibiotics accordingly.2

Addressing nutritional status

If you have a pressure ulcer, a healthcare professional (often a dietician or your GP) can advise you on how to optimise your diet if you are found to/suspected to be malnourished. Sometimes, they may prescribe supplements such as build-up drinks to support your nutrition.2

Possible complications of pressure ulcers 


Pressure ulcers can be painful, thus painkillers may be prescribed from time to time as needed whilst you are undergoing treatment.1 


Infection is the most common complication of pressure ulcers, and prompt treatment with antibiotics is essential.1 If infection spreads to surrounding tissues or bone, this can lead to cellulitis or osteomyelitis respectively. Severe infection can lead to the development of sepsis.1,10

Longer hospital stays

People who develop pressure ulcers in hospital stay an average of 5-8 days longer per ulcer which can have an impact on overall health and recovery.9

Reduced quality of life and increased risk of death. 

Often complex and lengthy treatment for pressure ulcers can have a negative impact on the quality of life of patients.4 Patients who develop pressure ulcers in hospital have been found to be 2.8 times more likely to die during their stay, and are more likely to be readmitted within 30 days of discharge.10


Pressure ulcers/sores are injuries to the skin and underlying tissue that can result from a combination of individual causes such as sustained pressure, friction, shear and moisture.1,10 Anyone can develop a pressure ulcer but the elderly, people with mobility and/or sensory problems, and malnourished people are at increased risk.

Preventing pressure ulcers is important if time-consuming treatment and complications are to be avoided. The risk of pressure ulcers can be reduced through proper skin care, pressure-relieving mattresses and cushions, good continence care and regular repositioning for those who are unable to do so themselves.

Most pressure ulcers can be graded between I and IV, with grade IV being the most serious. Managing a pressure ulcer involves reducing pressure on the area, treatment for the ulcer itself, and nutritional support for those who may be undernourished.


  1. Zaidi SRH, Sharma S. Pressure ulcer. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Sep 9]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK553107/ 
  2. Overview | Pressure ulcers: prevention and management | Guidance | NICE [Internet]. 2014 [cited 2023 Sep 11]. Available from: https://www.nice.org.uk/guidance/cg179 
  3. Mervis JS, Phillips TJ. Pressure ulcers: Pathophysiology, epidemiology, risk factors, and presentation. J Am Acad Dermatol. 2019 Oct;81(4):881–90. 
  4. Bauer K, Rock K, Nazzal M, Jones O, Qu W. Pressure ulcers in the United States’ inpatient population from 2008 to 2012: results of a retrospective nationwide study. Ostomy Wound Manage. 2016 Nov;62(11):30–8. 
  5. Saghaleini SH, Dehghan K, Shadvar K, Sanaie S, Mahmoodpoor A, Ostadi Z. Pressure ulcer and nutrition. Indian J Crit Care Med [Internet]. 2018 Apr [cited 2023 Sep 11];22(4):283–9. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5930532/ 
  6. National Pressure Ulcer Advisory Panel, European Pressure Ulcer Advisory Panel and Pan Pacific Pressure Injury Alliance (NPUAP/EPUAP/PPPIA) (2014) Prevention and Treatment of Pressure Ulcers: Quick Reference Guide. In: Haesler E (ed) Cambridge Media: Osborne Park, Australia. http://www.epuap.org/wp-content/uploads/2016/10/quick-reference-guide-digital-npuap-epuap-pppia-jan2016.pdf
  7. Zaver V, Kankanalu P. Negative pressure wound therapy. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Sep 11]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK576388/ 
  8. Choo J, Nixon J, Nelson A, McGinnis E. Autolytic debridement for pressure ulcers. Cochrane Database Syst Rev [Internet]. 2019 Jun 17 [cited 2023 Sep 11];2019(6):CD011331. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6573093/ 
  9. Wood J, Brown B, Bartley A, Margarida Batista Custódio Cavaco A, Roberts AP, Santon K, et al. Reducing pressure ulcers across multiple care settings using a collaborative approach. BMJ Open Qual [Internet]. 2019 Aug 20 [cited 2023 Sep 11];8(3):e000409. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6711432/ 
  10. Lyder CH, Wang Y, Metersky M, Curry M, Kliman R, Verzier NR, et al. Hospital‐acquired pressure ulcers: results from the national medicare patient safety monitoring system study. J American Geriatrics Society [Internet]. 2012 Sep [cited 2024 Apr 9];60(9):1603–8. Available from: https://agsjournals.onlinelibrary.wiley.com/doi/10.1111/j.1532-5415.2012.04106.x

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Helen Maginnis

MBChB, BSc. (MedSci) Genetics, University of Glasgow

Helen is a former NHS doctor living in Scotland. She discovered her love for medical writing while working in the charity sector with families affected by Huntington’s disease. She has a special interest in rare genetic disorders and has conducted laboratory research examining the impact of collagen IV gene mutations in mice. Helen values diversity in all its forms and is a passionate LGBTQ+ rights advocate.

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