Surgical Wound Infection: Recognition, Types, and Prevention
Updated: 4 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Medical emergency: Redness that spreads quickly, a high fever with shaking chills, a fast heartbeat, confusion, severe pain, or a wound that suddenly opens can signal a serious infection or sepsis after surgery. Call your surgical team or go to the nearest emergency department right away.
Quick Answer: What is a surgical wound infection?
A surgical wound infection, also called a surgical site infection, develops when bacteria enter the body through a surgical incision. Symptoms typically appear about 3 to 7 days after surgery and include redness, warmth, pain, pus-like discharge, odor, an opening incision and fever. Antibiotics are the most common treatment, and sometimes the surgeon must drain the wound.
What the research says
SSIs are uncommon but they add real time in hospital. A 2023 JAMA review reports that about 0.5% to 3% of patients who have surgery develop an infection at or near the incision, and that patients with an SSI stay in hospital about 7 to 11 days longer than those without one (Seidelman et al., JAMA, 2023).
Simple steps lower infection rates. In the same review, infection rates were 4.4% when razors were used for hair removal versus 2.5% with clippers, and 4.0% with chlorhexidine plus alcohol skin preparation versus 6.5% with povidone-iodine plus alcohol (Seidelman et al., JAMA, 2023).
About half of SSIs are preventable. The 2017 CDC guideline, which screened 5,759 titles and abstracts and drew on 170 studies, estimates that approximately half of SSIs can be prevented with evidence-based strategies, including a full-body shower or bath with soap or an antiseptic at least the night before surgery (Berríos-Torres et al., JAMA Surg, 2017).
Key takeaways
An SSI is an infection of the incision or of the tissues and organs near the surgery.
The CDC estimates that 1 to 3 in 100 people who have surgery develop one.
Most signs appear in the first week or so: redness, warmth, pain, pus-like discharge, odor, an opening in the incision, and fever.
Staph, strep, enterococci, and Pseudomonas are the usual bacteria, and they often come from the patient's own skin or gut.
Diabetes, obesity, smoking, malnutrition, and a weakened immune system raise the risk.
Antibiotics treat most infections, and prevention depends on both the hospital team and the patient.
What is a surgical wound infection?
Your skin is your first defense against infection. A surgical incision breaks through that barrier, which gives bacteria a chance to get in. Surgical infections do not happen often, partly because hospitals work hard to prevent them, but they can seriously slow healing when they do occur.
The U.S. Centers for Disease Control and Prevention (CDC) divides SSIs into three types, based on how deep they go.
Infection type | Area affected | Characteristics |
Superficial incisional | Skin and the tissue just under it | The most common type, accounting for more than 50% of surgical infections |
Deep incisional | Muscles and the connective tissue around muscles and organs | An example is an infection after an incision through the breastbone (sternum) |
Organ or space | Organs or the spaces between organs | Can occur when surgery affects nearby organs or the spaces between them |
What are the symptoms of a surgical wound infection?
Symptoms typically develop about 3 to 7 days after surgery, but they vary with the type of operation, and some infections appear later. Check your incision every day while it heals, and contact your surgical team if anything looks or feels different.
Symptom category | Warning signs to watch for |
Wound appearance | Redness or color changes that spread beyond the edge of the incision, and an opening in the incision line that gets longer, wider, or deeper |
Discharge and odor | Thick, cloudy, white or cream-colored pus, and a noticeable or unpleasant odor |
Physical sensation | Pain when you touch the wound or the skin around it, and an area that feels warm or hot |
Whole-body symptoms | Fever above 101°F (38.4°C), chills, and sweating |
Which bacteria cause surgical wound infections, and how do they get in?
Surgical wound infections are caused by bacteria, most often Staphylococcus aureus, along with group A strep, enterococci and Pseudomonas aeruginosa. Of the millions of kinds of bacteria, a few are responsible for most of them:
Staphylococcus aureus is the most common cause. About 30% of people carry it in the nose, where it is usually harmless until it gets inside the body. See our guide to staph infections.
Streptococcus pyogenes (group A strep) is the bacterium behind strep throat. It can live in the nose and throat and spread when people cough, sneeze, or talk.
Enterococci live in the intestines and usually cause no harm unless they reach a part of the body where bacteria do not belong, for example if bowel contents spill into the abdomen during surgery.
Pseudomonas aeruginosa can be present on the skin or on medical devices such as urinary catheters and ventilators.
Bacteria usually reach the wound in one of three ways:
Self-contamination: bacteria from your own skin, mucous membranes, or digestive tract get into the incision.
Direct contact: bacteria on medical equipment or on the hands of the care team reach the surgery site.
Airborne contamination: microorganisms in the air, such as those in respiratory droplets, settle in the wound.
What are the risk factors and wound classes for surgical wound infections?
Your overall health and the kind of surgery you have both affect your risk. Surgeons review these factors in advance so they can plan prevention and follow-up.
Risk category | Factors that raise infection risk |
Health conditions | Diabetes, obesity, and an existing infection |
Lifestyle and nutrition | Smoking (including e-cigarettes) and malnutrition |
Immune status | A weakened immune system or taking immunosuppressant medicines |
Surgeons also classify the surgical wound itself, because it shows how likely bacteria are to be present:
Clean wounds: no sign of inflammation or contamination, and no internal organ is entered.
Clean-contaminated wounds: the operation involves an internal organ, but the organ is not infected.
Contaminated wounds: the operation involves an organ that may spill its contents into the wound.
Dirty wounds: there is already an infection, which raises the risk that the surgical wound will become infected too.
What complications can a surgical wound infection cause?
A surgical wound infection stops the wound from healing properly and can delay your recovery from surgery. It can also lead to other problems:
An abscess, which is a pocket of pus
Cellulitis, an infection of the skin and soft tissue
Osteomyelitis, an infection of the bone
Sepsis, a life-threatening reaction to infection
How are surgical wound infections diagnosed, managed and treated?
Your surgical team will ask when your symptoms started and whether they have been getting worse. To find out which bacteria are involved, they take a sample of any pus or fluid from the wound, and they may remove a few stitches or staples to do this.
Antibiotics are the most common treatment, and they clear most infections. In some cases, the surgeon needs to do a procedure to drain an abscess or remove infected tissue. Even after the infection clears, you need to keep protecting the wound until it has healed so a new infection does not start. Your team will tell you how to care for it.
What can hospitals and patients do to prevent surgical wound infections?
Hospitals and surgeons in the U.S. follow CDC guidelines to lower the risk of SSIs, and the World Health Organization has published similar guidance, including 13 recommendations on measures before surgery. Many of these steps happen in the operating room, so it is reasonable to ask your surgeon what they do to reduce your risk.
What the surgical team may do
Give antibiotics only when they are indicated and time them so they are working when the incision is made (see our guide to prophylactic antibiotics)
Clean the skin with an alcohol-based antiseptic before the incision
Keep your body temperature and blood sugar in a healthy range during surgery
In some high-risk cases, use negative pressure wound therapy on the closed incision
What you can do before surgery
Tell your surgeon about any health problems, such as allergies, diabetes, or obesity, which can affect infection risk.
Quit smoking, including e-cigarettes, because smoking increases your risk.
Do not shave near the surgery site. Even a tiny razor cut can give bacteria a way in. If hair needs to be removed, the team can use clippers.
Ask whether you should use an antiseptic cleanser or soap when you shower, and shower or bathe at least the night before surgery.
What you and your visitors can do after surgery
Ask anyone who examines your wound to clean their hands first. It is fine to ask if you do not see them do it.
Ask family and friends to wash their hands with soap and water or use an alcohol rub, and ask them never to touch the wound or dressing.
Wash your own hands before and after you care for your wound.
Before you go home, make sure you understand how to care for the wound and who to call with questions.
How can you take care of yourself while a surgical wound heals?
Taking care of yourself while a surgical wound heals means following your surgeon's instructions, staying gently active and eating enough protein and vitamins. If you have had an infection, you may get specific directions to help prevent another one. A few general habits also support healing:
Keep moving. Gentle activity improves blood flow, which brings oxygen to healing tissue. Go slowly and follow your care team's advice.
Make calories count. Your body is fighting the infection and healing from surgery at the same time, so eat enough protein, iron, zinc, and vitamins A and C.
When should you see a healthcare provider about a surgical wound infection?
Contact your provider if surgical wound infection symptoms worsen despite medicine or come back, and get emergency care for spreading redness, high fever or confusion. Keep an eye on the wound for:
Swelling or redness
Pain when you gently touch the area
Pus or discharge from the wound
Fever or chills
Get emergency care for spreading redness, high fever with shaking chills, a fast heartbeat, confusion, or a wound that opens.
Conclusion
Surgical wound infections are not common, but they are serious enough to deserve attention. Knowing the warning signs, checking your incision daily, and calling your team early gives treatment the best chance to work. Prevention is shared. The hospital team handles sterile technique, antibiotics, and skin preparation, while you can help by stopping smoking, not shaving the area, managing health conditions like diabetes, keeping your hands clean, and following your wound-care instructions.
Related reading
Frequently Asked Questions
What is a surgical wound infection?
A surgical wound infection is an infection that develops at the site of a surgical incision after an operation, when bacteria get in through the cut.
How common are these infections?
The CDC estimates that 1 to 3 in 100 people who have surgery develop one. A 2023 review puts the range at about 0.5% to 3%.
What causes the infection?
Bacteria, most often Staphylococcus aureus, Streptococcus pyogenes, enterococci, or Pseudomonas aeruginosa, entering through the incision.
When do symptoms usually appear?
Most symptoms appear about 3 to 7 days after surgery, although some infections show up later.
What does infected discharge look like?
Infected discharge is typically thick and cloudy, and white or cream-colored, and it may have an unpleasant odor.
Is fever a sign of infection?
Yes. A fever above 101°F (38.4°C), especially with chills or sweating, can mean a surgical site infection.
What is a superficial incisional infection?
A superficial incisional infection is an infection limited to the skin and the tissue just under it around the incision. It is the most common type.
What is a deep incisional infection?
A deep incisional infection affects deeper layers such as muscle and the connective tissue around muscles and organs.
What is an organ or space infection?
An organ or space infection is an infection in an organ or in the space between organs that was affected during surgery.
Who is at higher risk for infection?
People with diabetes, obesity, malnutrition, an existing infection, or a weakened immune system, and people who smoke.
Does smoking affect infection risk?
Yes. People who smoke get more surgical infections, so quitting before surgery lowers your risk.
How are these infections diagnosed?
Doctors examine the wound, ask about your symptoms, and take a sample of any fluid or pus to identify the bacteria.
What is the main treatment?
Antibiotics. In some cases a surgeon also drains an abscess or removes infected tissue.
Can I prevent an infection?
Many can be prevented. You can help by quitting smoking, managing health conditions, not shaving near the site, keeping your hands clean, and following all instructions before and after surgery.
Why shouldn't I shave before surgery?
Shaving with a razor can irritate the skin and cause tiny cuts that give bacteria a path to enter. If hair needs to be removed, the surgical team can use clippers.
Sources
Cleveland Clinic. Surgical Wound Infection. Cleveland Clinic. Last updated June 17, 2025. https://my.clevelandclinic.org/health/diseases/surgical-wound-infection
Centers for Disease Control and Prevention. Surgical Site Infection Basics. Centers for Disease Control and Prevention. Last reviewed April 11, 2024. https://www.cdc.gov/surgical-site-infections/about/index.html
Seidelman JL, Mantyh CR, Anderson DJ. Surgical site infection prevention: a review. JAMA. 2023;329(3):244-252. PMID 36648463. https://doi.org/10.1001/jama.2022.24075
Berríos-Torres SI, Umscheid CA, Bratzler DW, et al. Centers for Disease Control and Prevention guideline for the prevention of surgical site infection, 2017. JAMA Surg. 2017;152(8):784-791. PMID 28467526. https://doi.org/10.1001/jamasurg.2017.0904
Allegranzi B, Bischoff P, de Jonge S, et al. New WHO recommendations on preoperative measures for surgical site infection prevention: an evidence-based global perspective. Lancet Infect Dis. 2016;16(12):e276-e287. PMID 27816413. https://doi.org/10.1016/S1473-3099(16)30398-X
Medical disclaimer
The information in this article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have about a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read here. If you think you may have a medical emergency, call your doctor or your local emergency number immediately.
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