New and improved: 2007 pressure ulcer definitions

Advances in wound care science and knowledge occur every day. In February 2007, the National Pressure Ulcer Advisory Panel (NPUAP), via a consensus conference, developed new definitions related to pressure ulcers and staging. Previously, a pressure ulcer was defined as an area “of localized tissue destruction caused by the compression of soft tissue over a bony prominence and an external surface for a prolonged period of time.”1 Now, a pressure ulcer is defined as:

…localized injury to the skin and/or underlying tissue usually over a bony prominence, as a result of pressure, or pressure in combination with shear and/or friction. A number of contributing or confounding factors are also associated with pressure ulcers; the significance of these factors is yet to be elucidated. 2

To elaborate, this new definition states that underlying tissue (such as muscle or adipose tissue), not just epidermis and dermis, can be affected by the forces that contribute to pressure ulcer development. It also incorporates the other mechanical forces (shear and friction) that can contribute to pressure ulcer development. Shear forces are often the primary factor for pressure ulcers that develop over the sacrococcygeal area.3 The new definition also states that many variables are associated with pressure ulcer development, and we may not yet be able to identify all of them or know the significance of each variable as it relates to each pressure ulcer.

Pressure ulcer staging was initially developed in 1975.4 The intent of staging then, as now, was to identify the degree of tissue damage identifiable in the wound. However, over the years staging has been used incorrectly to determine whether the pressure ulcer has improved or has deteriorated. Currently, the Minimum Data Set (MDS) tool used in long-term care facilities requires that a pressure ulcer be back-staged or down-staged to demonstrate improvement, which is an inappropriate use of the staging system. NPUAP’s 1995 statement recommended that “[r]everse staging should never be used to describe the healing of a pressure ulcer.”5 This is still a current recommendation from NPUAP

Stage I pressure ulcer


For example, once a pressure ulcer is assessed as a stage IV, it should always be documented as such. As this pressure ulcer heals by granulation, contraction, and eventually epithelialization to closure, the depth of tissue damage doesn’t change. Even if the wound bed is full of granulation tissue, that tissue is not the same as what was there before injury, nor is that tissue’s tensile strength the same as uninjured tissue. Even at the conclusion of the remodeling/maturation phase of wound healing, which can take many months, the repaired tissue’s tensile strength is less than uninjured tissue. Therefore, complete the MDS as per instructions, but include in the narrative documentation a comment such as “This pressure ulcer currently appears to be a stage III. However, it is a granulating stage IV with the bone and muscle no longer exposed.”

The definitions of the stages were revised in important ways:

Stage I Pressure Ulcer

Old definition:

[A]n observable, pressure-related alteration of intact skin whose indicators as compared to the adjacent or opposite area on the body may include changes in one or more of the following: skin temperature…, tissue consistency…, and/or sensation….

The ulcer appears as a defined area of persistent redness in lightly pigmented skin, whereas in darker tones, the ulcer may appear with persistent red, blue, or purple hues.5

New definition:

Intact skin with non-blanchable redness of a localized area usually over a bony prominence. Darkly pigmented skin may not have visible blanching; its color may differ from the surrounding area

Epithelializing stage II pressure ulcer


Further description: The area may be painful, firm, soft, warmer or cooler as compared to adjacent tissue. Stage I may be difficult to detect in individuals with dark skin tones. May indicate “at risk” persons (a heralding sign of risk).2

This new stage I definition reinforces that the epidermis remains intact, but there is some alteration in the appearance of the skin. In persons with light skin tones, this alteration may appear as erythema that doesn’t blanch. However, in individuals with dark skin tones, there may not be assessable blanching. It is important for the nurse to assess whether the patient has pain, increased firmness or softness, or change in temperature at the area of suspected ulceration when compared with surrounding tissue. For example, a resident might complain of heel pain, so the nurse blanches the skin of the heel. It blanches easily with rapid capillary refill, but the patient complains of pain at the site and the tissue feels mushy. This would be considered a stage I pressure ulcer.

Stage II Pressure Ulcer

Old definition:

Partial thickness skin loss involving epidermis, dermis, or both. The ulcer is superficial and presents clinically as an abrasion, blister, or shallow crater.5

New definition:

Partial thickness loss of dermis presenting as a shallow open ulcer with a red/pink wound bed, without slough. May also present as an intact or open/ruptured serum-filled blister.

Further description: Presents as a shiny or dry shallow ulcer without slough or bruising.* This stage should not be used to describe skin tears, tape burns, perineal dermatitis, maceration or excoriation. *Bruising indicates suspected deep tissue injury.2

In the old definition, the phrase “shallow crater” led to many caregivers under-staging shallow stage III pressure ulcers as stage II pressure ulcers. The epidermis is less than 1 mm thick, and the dermis is, on average, 2 mm thick.6 Therefore, stage II pressure ulcers are very shallow. Once the wound takes on the appearance of a crater, there is usually invasion into the subcutaneous tissue and the wound is truly a stage III pressure ulcer.

In the new definition for stage II, “shallow crater” has been replaced with “shallow open ulcer.” This definition clarifies that a stage II ulcer cannot have any slough in the wound base. It also clarifies that a blister, whether ruptured or still closed, is a stage II ulcer, as well. If bruising is present, this definition suggests that the nurse consider a suspected deep tissue injury, even if only partial thickness skin loss currently exists. Finally, the new stage II definition specifies the various skin abnormalities that are not stage II pressure ulcers. If a resident has a skin tear or incontinence-associated dermatitis, or if the resident scratches him- or herself and has resultant excoriations, these are not to be classified as stage II pressure ulcers.

Stage III Pressure Ulcer

Old definition:

Full thickness skin loss involving damage to, or necrosis of, subcutaneous tissue that may extend down to, but not through, underlying fascia. The ulcer presents clinically as a deep crater with or without undermining of adjacent tissue.5

New definition:

Full thickness skin 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.

Further description: The depth of a stage III pressure ulcer varies by anatomical location. The bridge of the nose, ear, occiput and malleolus don’t have subcutaneous tissue and stage III ulcers can be shallow. In contrast, areas of significant adiposity can develop extremely deep stage III pressure ulcers. Bone/tendon is not visible or directly palpable.2

This new definition specifies that a stage III pressure ulcer is full thickness, so it goes through the epidermis and dermis and into, but not through, the subcutaneous tissue. Dead space, in the form of undermining or tunneling, may be present with this type of pressure ulcer. In addition, the definition also states that the depth of a stage III pressure ulcer will vary depending on the anatomical location of the wound. Finally, this definition specifies that underlying structures, such as bone or tendon, cannot be seen in a stage III pressure ulcer.

Stage IV Pressure Ulcer

Old definition:

Full thickness skin loss with extensive destruction, tissue necrosis, or damage to muscle, bone, or supporting structures (e.g., tendon, joint capsule).5

New definition:

Full thickness tissue loss with exposed bone, tendon or muscle. Slough or eschar may be present on some parts of the wound bed. Often include undermining and tunneling.

Further description: The depth of a stage IV pressure ulcer varies by anatomical location. Bridge of nose, ear, occiput and malleolus do not have subcutaneous tissue and these ulcers can be shallow. Stage IV ulcers can extend into muscle and/or supporting structures (e.g., fascia, tendon or joint capsule) making osteomyelitis possible. Exposed bone/tendon is visible or directly palpable.2

The new stage IV definition clarifies that underlying structures, such as bone or muscle, are present in the base of the full thickness stage IV pressure ulcer. It reiterates that dead space, in the form of undermining or tunneling, is often present. As with the stage III definition, the stage IV definition states that the depth of a stage IV ulcer may vary depending on its anatomical location. It also reminds the practitioner that osteomyelitis is highly possible with a stage IV pressure ulcer, given the exposure of underlying structures. Should a stage IV pressure ulcer fail to heal, presence of osteomyelitis should be considered.

Unstageable Pressure Ulcers

There is also an expanded definition for unstageable pressure ulcers. The new definition defines an unstageable pressure ulcer as:

Full thickness tissue loss in which 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.

Further description: Until enough slough and/or eschar is removed to expose the base of the wound, the true depth, and therefore stage, cannot be determined. Stable (dry, adherent, intact without erythema or fluctuance) eschar on the heels serves as “the body’s natural (biological) cover” and should not be removed.2

This new definition for unstageable pressure ulcers describes both forms of nonviable (dead) tissue—slough and eschar. The definition states that the wound base must be clearly visualized before staging can occur. Finally, this definition also states that dry, intact, stable eschar on heels should not be debrided. The expert opinion regarding this is so strong that NPUAP decided it was important to include within this definition.

The heels are poorly perfused. There is very little subcutaneous tissue between the calcaneus (heel bone) and the skin. If necrotic heels are debrided, the risk for osteomyelitis and further debridement or amputation is very high. The pressure should be removed from these heels and the eschar kept dry and intact. Many practitioners use povidone-iodine to paint escharic heels to keep the eschar dry and to provide antisepsis to the skin.

Deep Tissue Injury

Deep tissue injury has been discussed among wound practitioners for several years. A case study on deep tissue injury was first published in 2003.7 NPUAP has developed a definition for suspected deep tissue injury and included it with other pressure ulcer definitions. Suspected deep tissue injury is defined as:

Purple or maroon localized area of discolored intact skin or blood-filled blister due to 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 as compared to adjacent tissue.

Further description: Deep tissue injury may be difficult to detect in individuals with dark skin tones. Evolution may include a thin blister over a dark wound bed. The wound may further evolve and become covered by thin eschar. Evolution may be rapid exposing additional layers of tissue even with optimal treatment.2

The following scenario explains deep tissue injury: A person falls at home and breaks hip and for three days remains undiscovered on the floor until neighbors notice that the mailbox is full and newspapers have not been picked up. In the emergency room, the nurse assesses and documents a large bruised-appearing purplish area over the individual’s sacrum. The person has an operation to repair a fracture and is transferred to the medical-surgical floor postoperatively. The admitting nurse assesses and documents the injured area over the individual’s sacrum and implements a repositioning schedule from side to side, avoiding supine positions. Three days postoperatively, the individual has developed a large necrotic area over the sacrum that the nurse and physician determine is a pressure ulcer. This is a suspected deep tissue injury. Although the injury to the tissues occurred while the individual was on the floor at home for three days, the extent of the injury wasn’t truly revealed until three days later. The pressure ulcer didn’t happen in the emergency room, the operating room, or on the medical-surgical floor, it happened on the floor at the patient’s home

Deep tissue injury


Having this new definition for deep tissue injury is beneficial. Previously, if a prac-titioner identified an individual with a suspected deep tissue injury, the practitioner had to decide whether to call it a stage I pressure ulcer (because the epidermis was intact) or an unstageable pressure ulcer. Now these wounds fit into a category. Once a deep tissue injury has occurred, the wound will likely deteriorate even if optimal treatment, such as positioning and initiation of pressure dispersion surfaces, is implemented.


The new definitions developed by NPUAP will better enable the caregiver to correctly document pressure ulcer assessment. They provide clarity related to wound bed presentation. The new definitions also address areas previously questioned, such as how to stage an intact blister and how to treat adherent heel eschar. These revised pressure ulcer definitions beg for revision of the MDS to promote consistency in documentation.


With thanks to the following members of Drake Center’s wound team for providing the photos: LuAnn Reed, MSN, RN, CRRN, WCC, Program Director; Ursula Sirk, BSN, RN, WCC; and Anne Blevins, BSN, RN, WCC.

Mary Arnold Long, MSN, RN, CRRN, CWOCN, APRN-BC, CLNC, is a clinical nurse specialist at Drake Center in Cincinnati, Ohio.

For further information, phone (513) 418-9493. To send your comments to the author and editors, please e-mail


  1. Wound, Ostomy, and Continence Nurses Society (WOCN). Guideline for Prevention and Management of Pressure Ulcers, WOCN Clinical Practice Guideline Series Glenview, Ill:WOCN Society, 2003.
  2. National Pressure Ulcer Advisory Panel. Pressure ulcer stages revised by NPUAP. February 2007. Available at:
  3. Bryant RA, Clark RAF Skin pathology and types of skin Damage. In: Bryant RA, Nix DP, eds. Acute & Chronic Wounds Current Management Concepts 3rd ed. St. Louis:Mosby 2006 103
  4. Shea JD Pressure sores: Classification and management Clinical Orthopaedics and Related Research 1975; 112 89-100.
  5. NPUAP Position on Reverse Staging of Pressure Ulcers NPUAP Report 1995; 4 (2).
  6. Wysocki AB Anatomy and physiology of skin and soft tissue. In: Bryant RA, Nix DP, eds. Acute & Chronic Wounds Current Management Concepts 3rd ed St. Louis:Mosby 2006:40 42.
  7. Black JM, Black SB Deep tissue injury Wounds 2003; 15 (11):380.

Topics: Articles , Clinical , MDS/RAI