Surgical Site Infection
Infection of the area where surgery was performed
Quick Facts
- Type: Postoperative infection
- Location: Incision or deeper surgical area
- Common signs: Redness, pain, drainage, fever
- Treatment: Antibiotics, wound care, sometimes drainage
Overview
A surgical site infection (SSI) is an infection that occurs at or near a surgical incision within a period after an operation, usually within about 30 days, or longer if an implant is involved. Surgery creates a break in the skin's protective barrier, and despite careful sterile technique, bacteria can sometimes enter and multiply in the healing tissue.
Infections can be superficial, involving only the skin and tissue just beneath the incision, or deeper, involving muscle, organs, or the space around an implant. Most SSIs are caught and treated successfully, but they can prolong recovery and, if untreated, lead to serious complications. Recognizing the early signs and getting prompt care is the key to a smooth recovery.
A degree of redness, swelling, and tenderness is normal in the first few days after any operation as the body begins to heal. The concern is when these signs worsen rather than settle, when drainage becomes thick or foul-smelling, or when fever develops. Knowing what a normally healing incision looks like makes it easier to spot a problem early.
Symptoms
Symptoms usually appear in the days to weeks after surgery and tend to worsen rather than improve over time.
- Increasing redness around the incision
- Swelling and warmth at the wound
- Pain or tenderness that is getting worse, not better
- Cloudy, yellow, or foul-smelling drainage or pus
- The incision opening or not healing as expected
- Fever or chills
A small amount of redness and discomfort early after surgery is normal, but spreading redness, pus, fever, or worsening pain are warning signs that need medical attention.
Causes
SSIs are caused by bacteria entering the wound. Common sources include:
- Skin bacteria: Organisms that normally live on the skin, such as staphylococci, are the most frequent cause.
- Bacteria from inside the body: Operations on the bowel or other areas with natural bacteria can introduce those organisms into the wound.
- Contamination during or after surgery: Bacteria can reach the wound through instruments, the environment, or during dressing changes.
Whether an infection takes hold depends on the number and type of bacteria, the kind of surgery, and the patient's ability to heal and fight infection.
Risk Factors
- Diabetes or high blood sugar
- Smoking
- Obesity
- A weakened immune system
- Long or emergency operations
- Surgery on areas with natural bacteria, such as the intestines
- Poor nutrition and advanced age
Diagnosis
Doctors diagnose an SSI mainly by examining the wound and reviewing symptoms.
- Wound examination: Looking for redness, warmth, swelling, and drainage.
- Wound culture: Testing a sample of drainage to identify the bacteria and guide antibiotic choice.
- Blood tests: To check for signs of infection in the body.
- Imaging: Ultrasound or CT may be used to find a deeper collection of pus (abscess) if the infection is not on the surface.
Treatment
Treatment depends on how deep and severe the infection is.
- Antibiotics: Often the mainstay, chosen based on the likely or confirmed bacteria.
- Opening and cleaning the wound: A superficial infection may need the incision opened to drain pus and remove infected tissue.
- Drainage of an abscess: Deeper collections of pus may need to be drained with a needle or a procedure.
- Wound care: Regular dressing changes and sometimes specialized dressings help the wound heal.
- Treating contributing factors: Controlling blood sugar and improving nutrition support healing.
Most infections clear with appropriate treatment, though deeper or implant-related infections can require more intensive care.
Prevention
- Follow all wound-care and hand-washing instructions after surgery
- Do not smoke, especially before and after an operation
- Keep blood sugar well controlled if you have diabetes
- Keep the incision clean and dry as directed
- Avoid touching the wound and do not remove dressings early unless told to
- Take any prescribed preventive antibiotics exactly as directed
When to See a Doctor
Contact your surgeon or doctor if you notice spreading redness, increasing pain, pus or foul-smelling drainage, a fever, or a wound that opens or will not heal. Seek emergency care right away if you have a high fever with chills, rapidly spreading redness, severe pain, confusion, a fast heartbeat, or feel very unwell, as these can be signs of a serious, body-wide infection (sepsis) that needs immediate treatment.
Frequently Asked Questions
What are the first signs of a surgical site infection?
Early signs include increasing redness, swelling, warmth, and pain around the incision that gets worse rather than better, along with cloudy or foul-smelling drainage. Fever or chills can also appear. If you notice these, contact your doctor promptly.
How soon after surgery do infections appear?
Most surgical site infections develop within about 30 days of surgery, often in the first one to two weeks. When an implant such as a joint or mesh is involved, an infection can sometimes appear months later.
How are surgical site infections treated?
Treatment usually involves antibiotics, and superficial wounds may need to be opened and cleaned to drain pus. Deeper collections may require drainage with a procedure, along with careful wound care and control of factors like blood sugar.
How can I lower my risk of a wound infection?
Follow wound-care and hand-hygiene instructions, keep the incision clean and dry, avoid smoking, control blood sugar if you have diabetes, and take any prescribed antibiotics as directed. Do not remove dressings early unless instructed.
When is a wound infection an emergency?
A surgical infection becomes an emergency if you have a high fever, rapidly spreading redness, severe pain, a fast heartbeat, confusion, or you feel very unwell. These may signal sepsis, a life-threatening reaction that needs immediate care.
References
- Centers for Disease Control and Prevention (CDC). Surgical Site Infection (SSI).
- MedlinePlus, U.S. National Library of Medicine. Surgical wound infection.
- Mayo Clinic. Sepsis — Symptoms and causes.
- World Health Organization (WHO). Global guidelines for the prevention of surgical site infection.