Surgical Wound Classes Explained: Clean, Contaminated, and Dirty

Guide to Class I–IV Surgical Wounds and Their Risks

A surgical wound is a cut or wound that occurs in the body during a surgical procedure. It generally occurs due to incision when a surgeon uses a scalpel or other surgical instrument. These wounds have different types, which can vary in size and location depending on the type of surgery.

4 Types of Surgical Wounds

Doctors classify surgical wounds into four main types, including clean, clean-contaminated, contaminated, and dirty. This classification system helps assess the risk of infection and guide appropriate wound management. In this section, we will do a detailed discussion on these four types of surgical wounds.
 

• Class I: Clean Wounds: These are typically elective, non-traumatic wounds with no presence of inflammation. Clean wounds do not involve your respiratory, alimentary, genital, or urinary tracts. These surgical wounds possess low infection rates and recover on their own over a period. Due to their location, these wounds do not require additional preventive care.
• Class II: Clean-contaminated Wounds: Clean-contaminated wounds occur after surgeries on alimentary, abdominal, genital, or urinary tracts under controlled circumstances. Although there is no risk of infection, it can increase the risk due to its location. Entering the urinary tract, which is not sterile, increases the risk of a surgical site infection. 
• Class III: Contaminated Wounds: Contaminated wounds occur when there is a presence of any infection or contact of a foreign object with the skin during the surgical procedure. This can increase the risk of infection around the operated area during the healing process. The presence of infection in the gastrointestinal tract can increase the high risk of infection after undergoing any operation.  
• Class IV: Dirty Wounds: These wounds involve faecal contamination, pus, or the presence of a perforated viscus. It specifically signifies traumatic injuries during a surgical procedure under dirty conditions or a delay in treatments after the surgery. These wounds possess a high risk of infection due to pre-existing infection or contamination.

What are the risk factors for infections in surgical wounds?

Surgical site infections can arise from various patient-related and procedure-related risk factors. Here, we will discuss them in detail:

1. Patient-related Risk Factors

Here are a few patient-related risk factors that can cause infections in surgical wounds:

1. Age: Elderly patients aged between 60 and 90 and infants are at higher risk due to a less robust and active immune system.
2. Diabetes: Individuals with uncontrolled blood sugar levels can impair wound healing and increase susceptibility to infection.
3. Obesity: Increased body fat can reduce blood supply to the surgical site and hinder healing.
4. Smoking: Smoking can negatively impact blood flow and oxygen delivery, delaying wound healing mechanisms.
5. Immunosuppression: Conditions or medications that suppress the immune system can increase the risk of infection.

2. Procedure-related Risk Factors

These are some common procedure-related risk factors that increase the chance of surgical wound infections:

1. Surgical duration: Longer surgeries, more than 8-9 hours, can increase the risk of infection due to prolonged exposure to the surgical site.
2. Emergency surgery: Doctors usually perform emergency surgeries under less-than-ideal conditions, increasing the risk of contamination.
3. Contaminated or dirty wounds: Wounds that can occur due to bowel spillage or existing infection have a higher risk of infection.
4. Inadequate surgical technique: Poor surgical techniques, improper tissue handling, and inadequate haemostasis can contribute to surgical site infection.
5. Blood transfusion: Patients who require blood transfusions are often those who have undergone more extensive or complicated surgeries, which are themselves associated with a higher risk of infection.
    

If you are experiencing increased pain, swelling or warmth around the wound, seek immediate medical attention. Surgical wounds can cause severe complications, such as dehiscence, infection, and sometimes organ failure. Timely treatment can prevent infections and serious complications.