Surgical Site Infections
Infections that develop at the site of an operation
Quick Facts
- Type: Post-operative infection
- Usual onset: Within about 30 days of surgery
- Common signs: Redness, pain, drainage, fever
- Treatment: Wound care, antibiotics, sometimes drainage
Overview
A surgical site infection is an infection that occurs at or near the place on the body where an operation was performed. It usually develops within about 30 days of surgery (or longer if an implant is involved). These infections are one of the more common complications of surgery, though careful surgical practices have reduced their frequency.
Surgical site infections are grouped by how deep they go: superficial infections involve only the skin, deeper infections involve the muscle and tissue beneath, and the most serious involve an organ or the space where surgery took place. Most are treatable, but some can become serious, so recognizing the warning signs and seeking care promptly is important.
Symptoms
Signs of a surgical site infection usually appear in the days to weeks after an operation and include:
- Increasing redness, swelling, or warmth around the incision
- Pain or tenderness that worsens rather than improves
- Pus or cloudy drainage from the wound
- An incision that opens or separates
- A foul odor from the wound
- Fever or chills
- Feeling generally unwell
Some swelling, mild redness, and discomfort are normal early after surgery. Warning signs are symptoms that worsen instead of improving, spreading redness, pus, or fever. Spreading redness with high fever or feeling very ill can signal a serious infection and needs urgent care.
Causes
Surgical site infections occur when bacteria enter the wound and multiply. Common sources and contributors include:
- Skin bacteria: Germs that normally live on the skin, such as staphylococci, are the most common cause.
- Contamination during surgery: Bacteria introduced at the time of the operation.
- Bacteria from inside the body: For example, from the intestines during abdominal surgery.
- Resistant bacteria: Some infections involve harder-to-treat organisms such as MRSA.
The risk depends on the type of surgery, the patient's health, and how the wound is cared for afterward.
Risk Factors
- Diabetes or poor blood sugar control
- Obesity
- Smoking
- A weakened immune system or use of steroids or chemotherapy
- Long or complex operations, or emergency surgery
- Older age and poor nutrition
- Surgery involving areas with more bacteria, such as the intestines
Diagnosis
Doctors diagnose a surgical site infection by examining the wound and reviewing symptoms:
- Wound examination: Checking for redness, swelling, warmth, drainage, and separation of the incision.
- Wound culture: Testing a sample of drainage or tissue to identify the bacteria and guide antibiotic choice.
- Blood tests: To look for signs of infection.
- Imaging: Ultrasound, CT, or other scans when a deeper or organ-space infection or abscess is suspected.
Treatment
Treatment depends on the depth and severity of the infection:
- Wound care: Cleaning the wound and, for some infections, opening the incision to allow drainage and proper healing.
- Antibiotics: Prescribed based on the type of infection and bacteria identified; serious infections may need intravenous antibiotics.
- Drainage of abscesses: Collections of pus may need to be drained.
- Surgery: Deep or organ-space infections sometimes require an operation to clean the area or remove infected material.
- Supportive care: Pain control, nutrition, and management of underlying conditions such as diabetes.
Prevention
- Follow all wound care and hygiene instructions after surgery
- Keep the incision clean and dry as directed
- Wash hands before touching the wound or dressing
- Do not smoke, especially around the time of surgery
- Keep blood sugar well controlled if you have diabetes
- Take preventive antibiotics if prescribed before surgery
- Report early signs of infection promptly
When to See a Doctor
Contact your surgeon or doctor if, after an operation, you notice increasing redness, swelling, warmth, pain, drainage, or an opening of the incision, or if you develop a fever. Catching an infection early makes it easier to treat.
Seek urgent or emergency care for:
- Rapidly spreading redness or red streaks from the wound
- High fever, chills, or feeling very unwell
- A fast heartbeat, confusion, or dizziness
- Severe pain or a wound that has opened widely
These can signal a serious or spreading infection, including sepsis, which is a medical emergency.
Frequently Asked Questions
What are the signs of a surgical site infection?
Watch for increasing redness, swelling, warmth, and pain around the incision, pus or cloudy drainage, a wound that opens, a foul odor, or fever. Symptoms that worsen rather than improve after surgery are a warning sign and should be reported.
When do surgical site infections usually appear?
Most appear within about 30 days of surgery, often in the first one to two weeks. If an implant such as a joint replacement is involved, an infection can develop later. Report any new or worsening wound symptoms to your surgeon.
How are surgical site infections treated?
Treatment may include cleaning and sometimes opening the wound for drainage, antibiotics chosen for the specific bacteria, and draining any collections of pus. Deep or organ-space infections may need additional surgery. Serious infections may require intravenous antibiotics.
When is a surgical wound infection an emergency?
Seek emergency care for rapidly spreading redness or red streaks, high fever or chills, a fast heartbeat, confusion, dizziness, or a wound that opens widely. These can signal a serious spreading infection or sepsis, which is a medical emergency.
Can surgical site infections be prevented?
Many can. Following wound care instructions, keeping the incision clean and dry, washing hands, not smoking, controlling blood sugar, and taking any prescribed preventive antibiotics all lower the risk. Reporting early signs promptly helps prevent complications.
References
- Centers for Disease Control and Prevention (CDC). Surgical Site Infection (SSI).
- MedlinePlus, U.S. National Library of Medicine. After Surgery.
- Mayo Clinic. Wound care after surgery.
- World Health Organization (WHO). Surgical site infection prevention.