Wound Classification


The definition of a wound is damage to the integrity of biological tissue, including skin, mucous membranes, and organ tissues. Various types of trauma can cause these, and it is critical to ensure wounds are cleaned and appropriately dressed to limit the spread of infection and further injury.[1][2] To correctly classify the cleanliness and condition of wounds, the CDC has established classification definitions composed of four classes of wound statuses:

  • Class 1 wounds are considered to be clean. They are uninfected, no inflammation is present, and are primarily closed. If the draining of these wounds is necessary, a closed draining method is necessary. Additionally, these wounds do not enter respiratory, alimentary, genital, or urinary tracts.
  • Class 2 wounds are considered to be clean-contaminated. These wounds lack unusual contamination. Class 2 wounds enter the respiratory, alimentary, genital, or urinary tracts. However, these wounds have entered these tracts under controlled conditions.
  • Class 3 wounds are considered to be contaminated. These are fresh, open wounds that can result from insult to sterile techniques or leakage from the gastrointestinal tract into the wound. Additionally, incisions made that result in acute or lack of purulent inflammation are considered class 3 wounds. 
  • Class 4 wounds are considered to be dirty-infected. These wounds typically result from improperly cared for traumatic wounds. Class 4 wounds demonstrate devitalized tissue, and they most commonly result from microorganisms present in perforated viscera or the operative field.[3]

Issues of Concern

The main issue of concern with the wound classification scheme is that it has low inter-rater reliability among healthcare providers.[3][4] Additionally, this wound classification scheme has been shown to not work as effectively in neonatal surgical wounds. A different wound classification scheme may be necessary for this demographic.[5]

The American College of Clinical Wound Specialists (ACCWS) emphasizes how difficult it is to find a common wound denomination. Each tissue that has to heal or the cause that induces the wound will necessarily have a different iter, a different approach. To give some examples, the peritoneal cavity or the intrauterine space have membranes with a substantial repair capacity, but the percentage of producing adhesions or fibrosis is high. The reparative processes will depend heavily on genetic, molecular, and immune factors. The same surgical approach may give different results: laparoscopy, hysterectomy, laparotomy.

The American Burn Association (ABA) points out that, despite advances in patient care and survival, there are still difficulties in administering the most appropriate treatments depending on the global geographic area. Furthermore, not only biological factors but also psychological ones merit consideration.

According to the statistical research of 2020, abdominal wounds are most likely to be incorrectly classified as clean wounds, delaying the patient's recovery.

Muscle injuries will respond differently depending on the cause: traumatic causes of sports activities or traumatic causes of war. Or, when the loss of muscle volume is significant, the metabolic environment will create anti-reparative molecular responses (lower amount of IGF-1 and pro-fibrotic activity).

Clinical Significance

The clinical significance of proper wound classification lies in its ability to help predict the likelihood of surgical site infections, postoperative complications, and reoperation.[6] Correctly classified wounds also can potentially aid in assessing morbidity, mortality, and quality of life.[7] Patients receiving grafts also benefit from this classification scheme, as it helps to evaluate the degree of bacterial contamination upon grafting and, by extension, the ability of the graft to heal correctly.[8]

The human body is not sterile. The infection results from dynamic interactions between a host, a potential pathogen, and the environment. It occurs when the microorganism successfully manages to evade the host's defense strategies, causing harmful changes in the host itself. The development of an infection is preceded by a series of complex interactions not yet fully known.

  1. The development of an infected wound depends on the pathogenicity and virulence of the microorganism and the immunocompetence of the host.
  2. The host/pathogen interaction does not always translate into a pathological form, and it is necessary to introduce new terms and definitions.
  3. Microbiological assessment by itself is not a reliable method for diagnosing an infected lesion, but a comprehensive, holistic patient assessment is also required.

The wounds do not all have the same conditions; therefore, different wounds support different communities of microorganisms. The acquisition of microbial species by wounds can result in three distinct consequences: contamination, colonization, and infection.

Colonization is not always synonymous with infection.

Surgical wound infection control began in the 1960s in the United States with the classification of wounds into four categories (clean, clean-contaminated, and dirty or infected) and with surveillance reports from Cruse and Foord. Subsequently, the Centers for Disease Control and Prevention (CDC) formulated definitions for the various hospital infections, further modified in 1992 when surgical wound infections became known as site infections. Subjective definitions of infected wounds led to the development of two wound classification systems: the ASEPSIS and the Southampton Wound Assessment Scale. Numerous tools based on different combinations of infection indicators have undergone development for open wounds.

Some criteria for recognizing infected wounds include the presence of abscess, cellulitis, or the presence of secretions (serous exudate accompanied by inflammation, purulent serum, purulent blood, and pus).

Additional suggested criteria include delayed healing; discoloration; a friable granulation tissue with ease to bleed; unexpected pain and/or irritation; pocketing at the wound's base; bridging of the epithelium or soft tissues; abnormal smell; wound degeneration.

Nursing, Allied Health, and Interprofessional Team Interventions

Research has determined that to accurately document a wound classification, implementing a curriculum that prioritizes wound classifications can result in a statistically significant increase in the accurate documentation of wound classifications.[9] [Level 1] 

A factor often overlooked is the patient's nutritional approach to improve the wound healing response. For example, a diabetic ulcer will need a careful food assessment and accompanying dietary changes not to make the wound worse and allow healing. Further, malnutrition does not lend itself to correct tissue repair. Some food supplements can help heal a wound; for example, arginine helps collagen storage, or glutamine helps the immune system.

Generally, the clinician assesses the wound, the nurse provides ongoing wound care and monitoring, and other healthcare personnel is involved in the patient's healing process. The presence of the psychologist can help with the possible emotional traumatic implications; the physiotherapist to improve or speed up the recovery processes of the patient's autonomy or to use tools (from electrostimulation to sensory stimulation, etc.) or exercises; the pharmacist with medication reconciliation and providing antibiogram information for infection treatment or prophylaxis; these are all options in the interprofessional team approach to wound care.

Nursing, Allied Health, and Interprofessional Team Monitoring

It is critical that healthcare teams accurately classify wounds and manage wounds appropriately to optimize patient-centered care and quality of life while minimizing infection and further wound trauma.[10]

(Click Image to Enlarge)
The photo shows a previous sternotomy; the wound has healed and is not infected, but shows a possible evolution in a hypertrophic scar.
The photo shows a previous sternotomy; the wound has healed and is not infected, but shows a possible evolution in a hypertrophic scar.
Contributed by Bruno Bordoni, PhD.
Article Details

Article Author

Timothy Herman

Article Editor:

Bruno Bordoni


5/4/2021 3:15:07 PM

PubMed Link:

Wound Classification



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