MAGENT

Surgical wound class: CDC/HICPAC wound classification (Mangram 1999)

Surgical wound class describes how contaminated an operative wound is likely to be at the time of the operation. As defined in the 1999 CDC/HICPAC guideline, there are four classes: I Clean, II Clean-Contaminated, III Contaminated and IV Dirty-Infected. You choose the class from what happened during the operation, and Magent's wound class calculator returns the matching label and the guideline's description.

Not a medical device. Not a diagnosis or dosing recommendation.

Use this calculator via API

What is surgical wound classification?

The classes sort operations by how much bacterial contamination the wound is likely to meet. A clean operation doesn't enter the airway, gut, genital or urinary tract. Entering one of those under controlled conditions makes it clean-contaminated. Accidental wounds, major breaks in sterile technique or gross spillage from the gut make it contaminated. An existing infection, old dirty wounds or perforated viscera make it dirty-infected.

Surgical records and surgical site infection surveillance often record the class. Magent's calculator doesn't decide the class. It takes the number you assign and returns the standard label and wording.

The surgical wound classification table

Class  Label                 In brief
1      I/Clean               No inflammation; airway, gut, genital and
                             uninfected urinary tracts not entered;
                             closed primarily
2      II/Clean-Contaminated One of those tracts entered under controlled
                             conditions, no unusual contamination
3      III/Contaminated      Open, fresh accidental wounds; major break in
                             sterile technique; gross spillage from the
                             gut; acute nonpurulent inflammation
4      IV/Dirty-Infected     Old traumatic wounds with dead tissue;
                             existing clinical infection; perforated viscera

Exact expression the calculator uses:

wound_class in {1, 2, 3, 4} as assigned by the caller (Mangram 1999 CDC/HICPAC Table 7 Class I-IV). magent does not inspect the wound. Not SSI rates. Not AMP selection.

Inputs

InputMeaning
wound_classWhole number from 1 to 4 that you assign

Any other value, such as 0, 5, 1.5 or a Roman numeral, returns the error invalid_wound_class. The response gives wound_class, class_label and description, the guideline's wording for that class.

How the calculation works

  1. Assign the class. From the operative findings, decide which of the four classes fits.
  2. Look up. The calculator returns the label (for example I/Clean) and the guideline description.

There's no arithmetic. The value of the tool is a consistent label and wording.

Worked examples

These use Magent's own expected values for the calculator.

Example 1: class 1

  1. Input 1.
  2. Label I/Clean: an uninfected operative wound with no inflammation, where the airway, gut, genital and uninfected urinary tracts aren't entered. Clean wounds are closed primarily, with closed drainage if a drain is needed.

Example 2: class 2

  1. Input 2.
  2. Label II/Clean-Contaminated: one of those tracts is entered under controlled conditions without unusual contamination. The guideline lists operations on the biliary tract, appendix, vagina and oropharynx here, provided there is no sign of infection or major break in technique.

Example 3: class 3

  1. Input 3.
  2. Label III/Contaminated: open, fresh, accidental wounds, operations with a major break in sterile technique or gross spillage from the gut, and incisions meeting acute nonpurulent inflammation.

Example 4: class 4

  1. Input 4.
  2. Label IV/Dirty-Infected: old traumatic wounds with retained dead tissue, and wounds involving existing clinical infection or perforated viscera.

An input of 0 returns invalid_wound_class.

History of surgical wound classification

Mangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR and the Hospital Infection Control Practices Advisory Committee published the guideline in Infection Control and Hospital Epidemiology in 1999, in "Guideline for prevention of surgical site infection, 1999". The four classes and their wording are set out in its Table 7.

When it's used

The class is recorded at the end of an operation, based on what was found and done.

Where it's used

Operating theatres, surgical records and infection-surveillance programmes.

Who uses it

Surgeons, anaesthetists, theatre nurses and infection-prevention teams. The calculator returns the label for the class assigned.

Limits of the calculation

  • The class depends on the judgement of whoever assigns it, and staff can disagree.
  • It describes contamination, not the patient's own risk factors.
  • The calculator doesn't give infection rates or choose antibiotics.
  • This page doesn't say what a result means for a particular person.

Clinical decisions belong to a qualified clinician who knows the patient.

  • Surgical Apgar scores blood loss, heart rate and blood pressure during an operation.
  • MESS scores the severity of a mangled limb.

Glossary

  • Surgical site infection: infection of the incision or the operated organ or space after surgery.
  • Primary closure: closing the wound at the end of the operation.
  • Viscera: internal organs, such as the bowel.
  • Nonpurulent inflammation: inflammation without pus.

Common mistakes

  • Entering a Roman numeral. The input is 1, 2, 3 or 4.
  • Classing a gut operation as clean. Entering the gut under control makes it clean-contaminated at least.
  • Treating the class as an infection rate. The calculator gives a label, not a percentage.
  • Classing by the indication instead of the findings. The class reflects what happened during the operation.

Source

Mangram AJ, et al. Guideline for prevention of surgical site infection, 1999. Infect Control Hosp Epidemiol. 1999;20(4):250-278. DOI: 10.1086/501620. PMID: 10219875

Frequently asked questions

What are the four surgical wound classes?

I Clean, II Clean-Contaminated, III Contaminated and IV Dirty-Infected.

Does the calculator decide the wound class?

No. You assign the class from the operative findings, and the calculator returns the label and description.

Is an appendix operation clean-contaminated?

The guideline lists appendix operations under clean-contaminated, provided there's no sign of infection or major break in technique. Perforated viscera fall under class IV, Dirty-Infected.

Does the calculator give infection rates?

No.

What happens if I enter 0?

The calculator returns the error invalid_wound_class.