|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
…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.
Stage 1 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.
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
The definitions of the stages were revised in important ways:
Stage I Pressure Ulcer
[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
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
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
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
Partial thickness skin loss involving epidermis,
dermis, or both. The ulcer is superficial and presents clinically
as an abrasion, blister, or shallow crater. 5
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
Epithelializing stage II pressure ulcer
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
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
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.
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
Stage IV Pressure Ulcer
Full thickness skin loss with extensive destruction, tissue
necrosis, or damage to muscle, bone, or supporting structures
(e.g., tendon, joint capsule). 5
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
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
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
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.
Deep tissue injury
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
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.
Having this new definition for deep tissue injury is beneficial.
Previously, if a practitioner 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.
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 firstname.lastname@example.org.
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.
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: www.npuap.org/pr2.htm.
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
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.
APA Style: Long, M.A. (2007). New
2007 pressure ulcer definitions. Retrieved <today's
date>, from SNJourney Web Site: http://www.snjourney.com/ClinicalInfo