Your skin is a natural barrier against infection. Even with many precautions and protocols to prevent infection in place, any surgery that causes a break in the skin can lead to an infection. Doctors call these infections surgical site infections (SSIs) because they occur on the part of the body where the surgery took place. If you have surgery, the chances of developing an SSI are about 1% to 3%. 

Types of surgical site infections

An SSI typically occurs within 30 days after surgery. The CDC describes 3 types of surgical site infections:

• Superficial incisional SSI. This infection occurs just in the area of the skin where the incision was made.

• Deep incisional SSI. This infection occurs beneath the incision area in muscle and the tissues surrounding the muscles.

• Organ or space SSI. This type of infection can be in any area of the body other than skin, muscle, and surrounding tissue that was involved in the surgery. This includes a body organ or a space between organs.

Signs and symptoms of surgical site infections

Any SSI may cause redness, delayed healing, fever, pain, tenderness, warmth, or swelling. These are the other signs and symptoms for specific types of SSI:

• A superficial incisional SSI may produce pus from the wound site. Samples of the pus may be grown in a culture to find out the types of germs that are causing the infection.

• A deep incisional SSI may also produce pus. The wound site may reopen on its own, or a surgeon may reopen the wound and find pus inside the wound.

• An organ or space SSI may show a discharge of pus coming from a drain placed through the skin into a body space or organ. A collection of pus, called an abscess, is an enclosed area of pus and disintegrating tissue surrounded by inflammation. An abscess may be seen when the surgeon reopens the wound or by special X-ray studies.

Causes and risk factors of surgical site infections

Infections after surgery are caused by germs. The most common of these include the bacteria Staphylococcus, Streptococcus, and Pseudomonas. Germs can infect a surgical wound through various forms of contact, such as from the touch of a contaminated caregiver or surgical instrument, through germs in the air, or through germs that are already on or in your body and then spread into the wound.

The degree of risk for an SSI is linked to the type of surgical wound you have. Surgical wounds can be classified in this way:

• Clean wounds. These are not inflamed or contaminated and do not involve operating on an internal organ.

• Clean-contaminated wounds. These have no evidence of infection at the time of surgery, but do involve operating on an internal organ.

• Contaminated wounds. These involve operating on an internal organ with a spilling of contents from the organ into the wound. 

• Dirty wounds. These are wounds in which a known infection is present at the time of the surgery.

These are other risk factors for SSIs:

• Having surgery that lasts more than 2 hours

• Having other medical problems or diseases

• Being an elderly adult

• Being overweight

• Smoking

• Having cancer

• Having a weak immune system

• Having diabetes

• Having emergency surgery

• Having abdominal surgery

Helping prevent surgical site infections

If you are having surgery, ask your doctor what you can do to reduce your risk for a surgical site infection. It's important to stop smoking before surgery and to tell your surgical team about your medical history, especially if you have diabetes or another chronic illness. Also, avoid shaving in the skin area that the surgeon is planning to operate through.

No matter how curious they are, loved ones should not touch your wound or surgical site. Carefully follow your doctor's instructions about wound care after surgery. Call your doctor if you develop a fever or pus, redness, heat, pain or tenderness near the wound or any other signs or symptoms of a surgical site infection. 

Treating surgical site infections

Most SSIs can be treated with antibiotics. Sometimes additional surgery or procedures may be required to treat the SSI. During recovery, make sure that friends and family members wash their hands before and after they enter your room. Make sure doctors, nurses, and other caregivers wash their hands, too.