Surgical Wound Classification Examples Essay

Quality-improvement initiative: Classifying and documenting surgical wounds

Interprofessional collaboration promoted a successful initiative to improve wound classification.

By Jennifer Zinn, MSN, RN, CNS-BC, CNOR, and Vangela Swofford, BSN, RN, ASQ-CSSBB

For surgical patients, operative wound classification is crucial in predicting postoperative surgical site infections (SSIs) and associated risks. Information about a patient’s wound typically is collected by circulating registered nurses (RNs) and documented at the end of every surgical procedure.

Because of its predictive value, wound classification plays a valuable role in driving quality-improvement (QI) initiatives that incorporate risk-adjusted outcomes. Incorrect classification can lead to inaccurate outcome analyses and evaluation, possibly causing skewed results and invalid conclusions. For example, if a hospital consistently underclassifies surgical wounds, this may suggest it has a higher SSI incidence than expected based on patient risks. QI initiatives this hospital might implement to address the increased SSI rate may be invalid because the data points were skewed and didn’t truly reflect patient risk. For accurate documentation, both surgeons and circulating RNs must understand the definitions of each wound class and the potential impact of inaccurate wound-class assignment.

Our QI initiative

When our hospital participated in the American College of Surgeons’ National Surgical Quality Improvement Project (NSQIP), we realized an opportunity existed to improve wound-classification documentation, because our documentation didn’t accurately correspond with NSQIP definitions. Quality assurance (QA) staff and operative-services nursing leaders began to discuss this issue. Ultimately, the discussion involved surgeons and served as the foundation of our QI initiative on wound classification.

Before starting the initiative, we had to establish the prevalence of incorrect documentation. Through focused chart audits, we found a 5% to 32% discrepancy rate between the description of the detailed surgical procedure in the surgeon’s dictated operative note and documentation of wound-class assignment in the operative record. This averaged to an 18% discrepancy rate. We realized the goal of accurately capturing wound classification for each surgical procedure would require a collaborative effort by an interprofessional team of engaged nursing staff, surgeons, and QA staff. So we began our QI project by forming a team and mapping out a plan for success.

Recruiting a surgeon champion

When implementing a QI initiative that crosses professions, champions for each discipline involved should be identified and included. We quickly identified and recruited a surgeon champion to provide feedback and input from a physician perspective. He fully supported nursing’s role in this initiative and interceded as an advocate for the project, patients, and nurses when disconnects with other physicians occurred.

As our interprofessional team discussed inaccurate wound classification and its potential impact on outcomes and initiatives, we realized this issue was multifocal and would require education of the entire surgical team. We also established a vision and goal for our initiative:

  • Vision: At the end of every surgical procedure, the circulating RN would verbally confirm the appropriate wound classification with the surgeon.
  • Goal: No more than a 5% discrepancy between the dictated operative note and documentation in the operative record system-wide by the end of the fiscal year.

To reach our goal, we committed to randomly auditing 20% of surgical procedures for each specialty at operating room (OR) sites in our health system monthly and reporting this information to stakeholders every quarter.

Implementation tools and resources

We knew intensive education supported with tools and the resources to understand and assign wound classification would be essential. So we divided our efforts into two prongs: staff education and surgeon education.

Surgeon education prong

One of our first steps was engaging and providing detailed information to physicians and physician leaders about the intent, purpose, and goal of our initiative. After gaining support from the chief of surgery, our surgeon champion sent memos to all surgeons explaining the significance of wound classification, describing our QI project, and emphasizing the importance of their participation.

A laminated pocket guide attached to this memo presented the four wound classifications, their definitions, and examples of common procedures performed in the OR for each class. This gave physicians a consistent and clear definition of each wound class. The surgeon champion attended surgical services and infection-prevention meetings to continue the wound-classification dialogue with his peers. Posters describing our initiative were placed in all physician OR lounges.

Staff education prong

At an educational in-service, staff members at all seven OR sites received detailed definitions and descriptions of the four wound classes. To promote information retention, education occurred within the month before project implementation. An in-service also was provided to staff from other departments that deal with SSIs, such as infection prevention and QA. All staff, including circulating RNs and surgical technologists, received the same wound-classification pocket guide given to surgeons. In addition, the pocket guide was enlarged and posted as a laminated wall chart in all 54 ORs to ensure consistent wound-class definitions. (See Surgical wound classifications.)

Creating an audit tool

An audit tool that would capture and record data and run and produce meaningful reports to stakeholders was vital to our project’s success. Our QA analyst created a tool that can:

  • randomly select 20% of procedures for each specialty for audit at all seven OR sites
    • automatically populate critical data points for further drilldowns and feedback (such as patient name, medical record number, surgery date, or surgeon) or record the circulating RN’s documentation of wound classification
  • enter important data points for focused drilldowns and feedback, including wound classification from the dictated operative note, comment section for additional notes, and name of staff member completing the OR record
  • run meaningful reports with valuable feedback to stakeholders that would promote continuing focus for improved outcomes. One type of report was the OR record with a wound-class mismatch between the surgeon’s dictated operative note and the circulating RN’s documentation. Another was the wound-classification audit summary, which provided system-wide, site, and specialty data.

Continuing efforts

Our efforts to improve wound-classification documentation didn’t stop with implementation of this QI initiative. We’ve maintained a continuous effort to identify and improve the tools and resources clinicians need to succeed. Nursing leaders sought solutions from staff on how to correct deficiencies. After the project launched, staff nurses were asked to give their perspectives on how it was progressing. Their feedback, which has been pivotal to our success, provided two crucial pieces of information:

  • The nurses didn’t believe all surgeons supported this effort. Some were frustrated by pushback from surgeons when trying to engage them in a wound-classification conversation at the end of a procedure. So our surgeon champion met with his surgeon peers and asked each one, “Are circulating nurses verifying wound classification with you at the end of every procedure?” To our nurses’ credit, the surgeons’ response was “yes.” When surgeons admitted they had questions of their own, our surgeon champion addressed their questions and concerns directly.
  • Nurses expressed uncertainty as to how to lead a conversation with surgeons about wound classification, and requested a script or set of leading questions to use at the end of every procedure. To guide the discussion, an algorithm with talking points was created. (See Wound-classification algorithm.)

Nurses also received additional educational in-services on wound classification. Some involved a Jeopardy-like game, critical-thinking activities, Q & A worksheets, and quarterly questions. (See Quarterly questions below.)

Quarterly questions

Quarterly questions allow nurses to participate in a self-assessment exercise as they think about their practice critically. Each quarter, a new question is distributed. Questions come in various formats, from those requiring short answers to crossword puzzles and riddles. Staff are encouraged to discuss the questions with their peers.

In each case, the operating room (OR) record showed a different wound classification than the surgeon’s dictated operative note indicated. The nurse’s wound-classification documentation appears next to each case number. Read each case through the dictated operative note. Before reading the section titled “Correct wound classification and rationale,” provide your own classification and rationale based on what you’ve learned in this article. Then read that section to see if you were right.

Case #1: OR record indicated a class II wound.

Preoperative diagnosis: Acute appendicitis
Postoperative diagnosis:

1. Acute appendicitis
2. Right ovarian cyst measuring 5 cm
Dictated operative note: The patient is a female found to have acute appendicitis on workup tonight in the emergency department (ED) after being sent by Dr. D for abdominal pain…The stump was hemostatic. Appendage was placed in an EndoCatch bag and extracted.
Correct wound classification and rationale: Class III
Appendectomy for acute appendicitis is a class III wound related to acute nonpurulent inflammation. Key clues from the dictated operative note: postoperative diagnosis of acute appendicitis and the patient’s ED admission.

Case #2: OR record indicated a class II wound.

Preoperative diagnosis: Perforated sigmoid colon
Postoperative diagnosis: Perforated sigmoid colon

Dictated operative note: The correct patient and procedure were verified. A midline incision in the lower abdomen just skirting the umbilicus was used, and dissection was carried down through subcutaneous tissue and midline fascia…There was a lot of edema of the anterior abdominal wall. The peritoneum was entered under direct vision. There was grossly feculent, foul-smelling fluid free in the peritoneal cavity, which was suctioned. There was marked diffuse peritonitis. Small bowel loops were distended and matted with fibrinous exudates. The dissection was carefully carried down in the pelvis with blunt dissection, dividing inflammatory adhesions. Several large pockets of grossly purulent and feculent material were entered and broken up; these were cultured. All loculations were completely broken up, suctioned, and irrigated.

Correct wound classification and rationale: Class IV

Perforated viscera and stool in the wound indicate a class IV wound related to perforated viscera/ stool, which suggest the organisms causing potential infection were present in the operative field before surgery. Key clues from the dictated operative note: grossly feculent, foul-smelling fluid, marked diffuse peritonitis, grossly purulent and feculent material, cultures, and postoperative diagnosis of perforated sigmoid colon.

Case #3: OR record indicated a class II wound.

Preoperative diagnosis: Tonsillitis
Postoperative diagnosis: Tonsillitis

Dictated operative note: The patient was placed in the supine position and, under general endotracheal anesthesia, the tonsils were removed using blunt and Bovie electrocoagulation dissection. They were exudative. There was a considerable amount of purulent material, and the patient was placed on antibiotics again (I.V.) as well as Decadron. Once this was completed, the stomach was suctioned and the tonsillar beds were clear of bleeding.

Correct wound classification and rationale: Class IV

Purulent material in the wound suggests the organisms causing a potential infection were present in the operative field before surgery. Key clues from the dictated operative note: exudate present, considerable amount of purulent material, the need for antibiotics, and postoperative diagnosis of tonsillitis.

Project outcome

Our initiative to accurately capture the correct wound classification met the goal of a discrepancy rate of 5% or less for fiscal year (FY) 2009—a rate we maintained for FY 2010 and 2011. Some of our OR sites exceeded that goal, demonstrating a 0% discrepancy rate. (See System-wide wound-classification discrepancy rate, 2008-2011.)

During this time, almost 14,000 dictated operative notes were audited. Other successful project outcomes included enhanced communication among OR team members, national recognition through podium presentations at national conferences, and selection as one of the five best practices by the American College of Surgeons’ NSQIP in 2011.

Our project demonstrated the power of interprofessional teamwork, which strength¬ened collegial relationships among staff. We encourage all clinicians to engage in important conversations with peers and ask crucial questions that help transform practices in your setting.

Selected references

Berard F, Gandon J. Postoperative wound infections: the influence of ultraviolet irradiation of the operating room and of various other factors. Ann Surg. 1964;160(suppl 2):1-192.

Burlingame BL. OR fire extinguishers; classifying wounds and minor procedures; antibiotic infusion time; mopping after minor procedures. AORN J. 2006;83(6):1384-93.

Devaney L, Rowell KS. Improving surgical wound classification—why it matters. AORN J. 2004;80(2):208-9, 212-23.

Nichols RL. Classification of the surgical wound: a time for reassessment and simplification. Infect Control Hosp Epidemiol. 1993;14(5):253-4.

Paige J. Tissue handling. In: Rothrock JC, Seifert PC, eds. Assisting in Surgery: Patient-Centered Care. Denver, CO: Competency & Credentialing Institute;2009:74-106.

Zinn JL. Surgical wound classification: communication is needed for accuracy. AORN J. 2012;95(2):274-8.

Zinn JL, Swofford V. What is wound classification? Speech presented at: 57th Annual AORN Congress; March 18, 2010; Denver, CO.

Zinn JL, Swofford V. Wound classification: Transforming surgical quality, one procedure at a time. Speech presented at: ANCC Magnet Conference; October 14, 2012; Los Angeles, CA.

The authors work at Cone Health in Greensboro, North Carolina. Jennifer Zinn is a clinical nurse specialist in operative services. Vangela Swofford is a quality-improvement facilitator.

Surgical wound classifications

The classification system shown here was developed to help clinicians identify and describe the degree of bacterial contamination of surgical wounds at the time of surgery. It was developed initially by the American College of Surgeons and adapted in 1985 by the Centers for Disease Control and Prevention.

Class I: Clean

  • Uninfected operative wound where no inflammation is encountered and respiratory, GI, genital, and urinary tracts aren’t entered.
  • Wounds are primarily closed, and a drain (if needed) is connected to a closed system.
  • Risk of infection: 2% or lower
  • Examples of clean surgical procedures: lumpectomy; mastectomy; axillary node dissection; vascular bypass graft; exploratory laparotomy; exploratory or diagnostic laparo¬scopy; adhesion lysis; ventral, inguinal, femoral, or incisional hernia repair; thyroidectomy; parathyroidectomy; total hip or knee replacement; laparoscopic gastric banding; Nissen fundoplication; abdominal aortic aneurysm repair; carotid endarterectomy; Port-a-Cath® insertion; splenectomy; MammoSite procedure; endovascular stent graft; vena cava filter insertion; false aneurysm repair; splenectomy; lumbar laminectomy; craniotomy for tumor; rotator-cuff repair; temporal artery biopsy; carpal tunnel repair; coronary artery bypass grafting; transverse rectus abdominis myocutaneous breast reconstruction; stereotactic biopsy; ventriculoperitoneal shunting

Class II: Clean/contaminated

Operative wound that enters the respiratory, GI, genital, or urinary tract under controlled conditions without unusual contamination when no infection or major break in technique has occurred

  • Risk of infection: 5% to 15%
  • xamples of clean/contaminated surgical procedures:cholecystectomy with chronic inflammation, colectomy, colostomy reversal, bowel resection for ischemic bowel, roux-en-Y gastric bypass, laryngectomy, incidental or routine appendectomy, small-bowel resection, transurethral resection of prostate, Whipple pancreaticoduodenectomy, abdominal perineal resection, gastrostomy tube placement, vaginal hysterectomy, dental extractions, alveoloplasty

Class III: Contaminated

  • Open, fresh, accidental wound from surgery with a major break in sterile technique or gross spillage from GI tract; incision in which acute, nonpurulent inflammation is encountered (including necrotic tissue without evidence of purulent drainage, such as dry gangrene).
  • Risk of infection: greater than 15%
  • Examples of contaminated surgical procedures:cholecystectomy or appendectomy for acute inflammation, bile spillage during cholecystectomy, cholecystectomy for acute inflammation, open cardiac massage, bowel resection for infarcted or necrotic bowel

Class IV: Dirty/infected

  • Old traumatic wounds with retained devitalized tissue; procedures with existing clinical infection (purulence already present in wound) or perforated viscera.
  • Risk of infection: greater than 30%
  • Examples of dirty/infected surgical procedures or conditions:
    incision and drainage of perirectal abscess, perforated bowel repair, peritonitis, appendectomy with perforation and/or pus noted, perforated gastric ulcer, ruptured appendectomy, open fracture with prolonged time in the field before treatment, dental extractions with abscess

Wound-classification algorithm

Two versions of an algorithm were created for the quality-improvement project on wound classification at Cone Health in North Carolina. The one currently used (shown here) arose from continued surgeon engagement and emphasizes the importance of interprofessional collaboration. Wound classification has been incorporated into our surgical checklist as a trigger to initiate this conversation between staff and surgeons.

System-wide wound-classification discrepancy rate, 2008-2011

Before the quality improvement (QI) project, the discrepancy rate between the surgeon’s dictated operative note and documentation of wound-class assignment in the operative record ranged from 5% to 32%. This averaged to an 18% discrepancy rate.

After the QI project was implemented, we met the goal of a discrepancy rate of 5% or

less (fiscal years 2009, 2010, and 2011). Some of our OR sites exceeded that goal and consistently demonstrated a 0% discrepancy rate.

Related Articles:

An overview of surgical site infections: aetiology, incidence and risk factors

Finn Gottrup
Professor of Surgery
University of Southern Denmark, The University Center of Wound Healing, Department of Plastic Surgery
Odense Hospital, Denmark

Andrew Melling
Research Fellow – Nursing,
Professorial Unit of Surgery,
University Hospital of North Tees, Stockton-on-Tees, UK

Dirk A. Hollander
Surgeon, Trauma Surgeon
Surgical Center,
Bethanien Hospital, Frankfurt, Germany

Published: Sept 2005
Last updated: Sept 2005
Revision: 1.0

Keywords: Surgical site infection (SSI); sepsis; healthcare associated infections (HAIs); wound care; infection control.

Key Points

  1. Surgical site infections (SSIs) are a real risk associated with any surgical procedure and represent a significant burden in terms of patient morbidity and mortality, and cost to health services around the world.

  2. A multitude of risk factors influence the development of SSIs and awareness of these will help to promote effective preventive strategies.

  3. Assessment tools such as the Centers for Disease Control definitions, ASEPSIS and the Southampton Wound Assessment Scale are needed to accurately identify and classify SSIs.


Infection has always been a feature of human life and sepsis in modern surgery continues to be a significant problem for healthcare practitioners across the globe. This paper describes the factors that influence surgical wound healing and the risk of surgical site infection.


Until the middle of the 19th century, when Ignaz Semmelweis and Joseph Lister became the pioneers of infection control by introducing antiseptic surgery, most wounds became infected. In cases of deep or extensive infection this resulted in a mortality rate of 70-80% [1]. Since then a number of significant developments, particularly in the field of microbiology, have made surgery safer. However, the overall incidence of healthcare associated infections (HAIs) remains high and represents a substantial burden of disease.

In 1992, the US Centers for Disease Control (CDC) revised its definition of 'wound infection', creating the definition 'surgical site infection' (SSI) [2] to prevent confusion between the infection of a surgical incision and the infection of a traumatic wound. Most SSIs are superficial, but even so they contribute greatly to the morbidity and mortality associated with surgery [3][4]. Estimating the cost of SSIs has proved to be difficult but many studies agree that additional bed occupancy is the most significant factor. A review of the incidence and economic burden of SSIs in Europe estimated that the mean length of extended stay attributable to SSIs was 9.8 days, at an average cost per day of €325 [4].

Healing by primary intention

Surgical wounds may heal by primary intention, delayed primary intention or by secondary intention. Most heal by primary intention, where the wound edges are brought together (apposed) and then held in place by mechanical means (adhesive strips, staples or sutures), allowing the wound time to heal and develop enough strength to withstand stress without support. The goal of surgery is to achieve healing by such means with minimal oedema, no serous discharge or infection, without separation of the wound edges and with minimal scar formation. On occasion, surgical incisions are allowed to heal by delayed primary intention where non-viable tissue is removed and the wound is initially left open. Wound edges are brought together at about 4-6 days, before granulation tissue is visible [5]. This method is often used after traumatic injury or dirty surgery.

Healing by secondary intention

Healing by secondary intention happens when the wound is left open, because of the presence of infection, excessive trauma or skin loss, and the wound edges come together naturally by means of granulation and contraction [6].

Experimentally as well as clinically it has been shown that a delay in wound closure of four to five days increases the tensile strength of the wound as well as resistance to infection. The overall rate of SSIs in traumatic war wounds using delayed principles was 3-4%, compared with more than 20% after primary closure [7]. In civilian practice, delayed healing has been used successfully in cases of severe incisional abscesses, mainly after laparotomy. Another benefit of delayed closure is the cosmetic result after healing. The appearance of a wound after a delay of four to five days is comparable to that of primary closure. A wider scar follows late closure (after 10-14 days), although this is cosmetically much better than the result obtained after the healing of an open granulating wound.

Factors influencing SSIs

Many factors influence surgical wound healing and determine the potential for, and the incidence of, infection [8][Figure 1]. The level of bacterial burden is the most significant risk factor [9][10][11], but modern surgical techniques and the use of prophylactic antibiotics have reduced this risk.

Figure 1 - Factors that affect surgical wound healing

[Adapted from Buggy D, Lancet 2000 [8]]

A system of classification for operative wounds that is based on the degree of microbial contamination was developed by the US National Research Council group in 1964 [9]. Four wound classes with an increasing risk of SSIs were described: clean, clean-contaminated, contaminated and dirty [Table 1]. The simplicity of this system of classification has resulted in it being widely used to predict the rate of infection after surgery.

Clean Elective, not emergency, non-traumatic, primarily closed; no acute inflammation; no break in technique; respiratory, gastrointestinal, biliary and genitourinary tracts not entered. 

Urgent or emergency case that is otherwise clean; elective opening of respiratory, gastrointestinal, biliary or genitourinary tract with minimal spillage (e.g. appendectomy) not encountering infected urine or bile; minor technique break. 

Contaminated Non-purulent inflammation; gross spillage from gastrointestinal tract; entry into biliary or genitourinary tract in the presence of infected bile or urine; major break in technique; penetrating trauma <4 hours old; chronic open wounds to be grafted or covered. 
Dirty Purulent inflammation (e.g. abscess); preoperative perforation of respiratory, gastrointestinal, biliary or genitourinary tract; penetrating trauma >4 hours old. 

[Adapted from Berard F, Gandon J, Ann Surg 1964 [9]]

Rates of infection

Infection rates in the four surgical classifications (clean, clean-contaminated, contaminated and dirty wounds) have been published in many studies but most literature refers to the work of Cruse and Foord as a benchmark for infection rates [10][11]. Before the routine use of prophylactic antibiotics infection rates were 1-2% or less for clean wounds, 6-9% for clean-contaminated wounds, 13-20% for contaminated wounds and about 40% for dirty wounds [10][11]. Since the introduction of routine prophylactic antibiotic use, infection rates in the most contaminated groups have reduced drastically. Infection rates in US National Nosocomial Infection Surveillance (NNIS) system hospitals were reported to be: clean 2.1%, clean-contaminated 3.3%, contaminated 6.4% and dirty 7.1% [12]. There is, however, considerable variation in each class according to the type of surgery being performed [13]

Preventive techniques

The surgical technique used can affect the infection rate in various ways, for example in relation to skin preparation, shaving and wound closure.

Skin preparation: The skin is colonised by various types of bacteria, but up to 50% of these are Staphylococcus aureus[14]. In analyses of contamination rates after cholecystectomy, the main source of wound contamination was found to be the skin of the patient [15]. For this reason, preoperative preparation should be performed. Evidence has shown that the use of a preoperative wash containing chlorhexidine decreases the bacterial count on skin by 80-90%, resulting in a decrease in preoperative wound contamination [16]. The effect on SSI incidence has, however, been more difficult to demonstrate and it is possible that prolonged washing releases organisms from deeper layers of the skin.

Shaving: It is now recognised that shaving damages the skin and that the risk of infection increases with the length of time between shaving and surgery [10]. In one study, if the patient had been shaved more than two hours before surgery the clean wound infection rate was found to be 2.3% [11]. However, if patients had not been shaved but their body hair had been clipped the rate was 1.7%, and if they had not been shaved or clipped the rate dropped to 0.9% [11]. If shaving is essential, it should be performed as close to the time of surgery as possible.

Wound closure: The healing of closed surgical wounds depends on many factors, one of the most complex of which is the influence of technique and expertise [7]. The incidence of SSIs in relation to the different types of closure techniques used is shown in Table 2.

Opening and re-closure timesReinfection rate
Opening and re-closure at once 50% 
Opening and re-closure after two days 


Opening and re-closure after four days 5% 
Opening and re-closure after nine days 10% 

Note: all wounds were closed under antibiotic cover.

[Adapted from Gottrup, F. Wound healing and principles of wound closure. In: Holström H, Drzewieck KT (Eds). The Scandinavian Handbook of Plastic Surgery. Malmoe: Studenterliteraturen, 2005 (In press).]

Once wounding has occurred, the surgeon has control over several factors concerning the wound itself that may reduce susceptibility to infection. The duration of surgery is one factor that influences the wound infection rate. Procedures that take longer than two hours are associated with higher infection rates [17][18]. This may be related to desiccation or maceration of the wound edges, an increase in the number of bacteria that accumulate within the wound, and decreased temperature and hypovolaemia leading to peripheral vasoconstriction and therefore poorly perfused skin. Fewer bacteria are required to produce an infection in the presence of necrotic tissue, foreign bodies, haematomas, seromas and poor tissue perfusion.

Although infection cannot occur without any bacterial burden or contamination, the presence of bacteria in a wound does not inevitably result in an infection. Many different factors determine the potential for and incidence of infection [Figure 1].

Identifying surgical site infections

The most widely recognised definition of infection, which is used throughout the USA and Europe, is that devised by Horan and colleagues and adopted by the CDC [2]. This splits surgical site infections into three groups - superficial and deep incisional SSIs and organ-space SSIs - depending on the site and the extent of infection. The definitions of superficial and deep infections are summarised in Table 3. The CDC definition states that only infections occurring within 30 days of surgery (or within a year in the case of implants) should be classified as SSIs.

Superficial incisional surgical site infectionsDeep incisional surgical site infections
Superficial incisional surgical site infections must meet the following two criteria [2]:
  • occur within 30 days of procedure

  • involve only the skin or subcutaneous tissue around the incision.


At least one of the following criteria:

  • purulent drainage from the incision

  • organisms isolated from an aseptically obtained culture of fluid or tissue from the incision

  • at least one of the following signs or symptoms of infection - pain or tenderness, localised swelling, redness or heat - and the incision is deliberately opened by a surgeon, unless the culture is negative

  • diagnosis of superficial incisional SSI by a surgeon or attending physician

The following are not considered superficial SSIs:

  • stitch abscesses (minimal inflammation and discharge confined to the points of suture penetration)

  • infection of an episiotomy or neonatal circumcision site

  • incisional SSIs that extend into the fascial and muscle layers (see deep SSIs).

Deep incisional surgical site infections must meet the following three criteria [2]:
  • occur within 30 days of procedure (or one year in the case of implants)

  • are related to the procedure

  • involve deep soft tissues, such as the fascia and muscles.


At least one of the following criteria:

  • purulent drainage from the incision but not from the organ/space of the surgical site

  • a deep incision spontaneously dehisces or is deliberately opened by a surgeon when the patient has at least one of the following signs or symptoms - fever (>38°C), localised pain or tenderness - unless the culture is negative

  • an abscess or other evidence of infection involving the incision is found on direct examination or by histopathologic or radiological examination

  • diagnosis of a deep incisional SSI by a surgeon or attending physician.


[Adapted from Horan et al [2]]

Wound infections have been subdivided according to the following clinically related subgroups [19]:

Aetiology: in a primary infection, the wound is the primary site of infection, whereas a secondary infection arises following a complication that is not directly related to the wound;

Time: an early infection presents within 30 days of a surgical procedure, whereas an infection is described as intermediate if it occurs between one and three months afterwards and late if it presents more than three months after surgery;

Severity: a wound infection is described as minor if there is discharge without cellulitis or deep tissue destruction, and major if the discharge of pus is associated with tissue breakdown, partial or total dehiscence of the deep fascial layers of the wound, or if systemic illness is present.

Wound assessment

No validated universal system is designed specifically to aid the assessment and management of surgical wounds. The most commonly used, the CDC definition, employs stringent criteria to classify infection. Several other wound scoring systems exist and two of the best are ASEPSIS [Figure 2] and the Southampton Wound Assessment Scale [Figure 3]. These enable surgical wound healing to be graded according to specific criteria, usually giving a numerical value, and therefore provide a more objective assessment of the wound [20][21].

Figure 2 - ASEPSIS wound scoring system

[Adapted from Wilson AP et al, Lancet 1986 [20] with permission from Elsevier]

Figure 3 - Southampton wound scoring system

[Adapted from Bailey IS et al, BMJ 1992; 304: 469-71 [21] with permission from the BMJ Publishing Group]

The ASEPSIS system was devised to assess wounds resulting from cardiothoracic surgery, while the Southampton scale was designed for use in the postoperative assessment of hernia wounds. The Southampton system is much simpler than the ASEPSIS system, with wounds being categorised according to any complications and their extent [21]. Both systems, however, have been developed for use following specific types of surgery and this may limit their usefulness.


In spite of the use of prophylactic antibiotics, SSIs are still a real risk of surgery and represent a substantial burden of disease for both patients and healthcare services in terms of morbidity, mortality and economic cost. Changes in definition have focused attention on infection of the surgical incision, and factors associated with SSIs are now being studied with a view to limiting the risk of infection.

Research has shown that surgical techniques, skin preparation and the timing and method of wound closure are significant factors that can influence the incidence of subsequent infection. Antibiotic prophylaxis has also had a positive impact after certain types of surgery. Many other factors have been identified as having an effect on the potential for infection and healthcare professionals should consider these before, during and after surgery.


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17. Haley RW, Culver DH, Morgan WM, White JW, Emori TG, Hooton TM. Identifying patients at high risk of surgical wound infection. A simple multivariate index of patient susceptibility and wound contamination. Am J Epidemiol 1985; 121(2): 206-15.

18. Jepsen OB, Larsen SO, Thomsen VF. Post-operative wound sepsis in general surgery. II. An assessment of factors influencing the frequency of wound sepsis. Acta Chir Scand Suppl 1969; 396: 80-90.

19. Peel ALG. Definition of infection. In: Taylor EW, editor. Infection in Surgical Practice. Oxford: Oxford University Press, 1992; 82-87.

20. Wilson AP, Treasure T, Sturridge MF, Gruneberg RN. A scoring method (ASEPSIS) for postoperative wound infections for use in clinical trials of antibiotic prophylaxis. Lancet 1986; 1(8476): 311-3.

21. Bailey IS, Karran SE, Toyn K, Brough P, Ranaboldo C, Karran SJ. Community surveillance of complications after hernia surgery. BMJ 1992; 304(6825): 469-71.

All materials copyright © 1992-Feb 2001 by SMTL, March 2001 et seq by SMTL unless otherwise stated.

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