Postoperative Wound Infection

Surgery can save lives, but infections at the surgical site remain a common complication that affects millions of patients each year, increasing hospital stays and healthcare costs while threatening recovery.

Table of contents

• What is a Postoperative Wound Infection?
• Types of Surgical Site Infections
• How Common Are These Infections?
• What Causes Postoperative Wound Infections?
• Risk Factors for Infection
• Signs and Symptoms
• How Infections Are Diagnosed
• Treatment Options
• Prevention Strategies
• Recovery and Outlook
• When to Contact Your Healthcare Provider

What is a Postoperative Wound Infection?

A postoperative wound infection, also called a surgical site infection (an infection that develops at the place where surgery was performed), is an infection that develops after you have surgery. These infections happen when bacteria (tiny organisms that can cause disease) get into your body through the cuts your surgeon makes during the operation^[1].

Before doctors understood how infections spread and began using antiseptic techniques, surgical infections were extremely common and often led to serious outcomes like limb amputation or death. The adoption of cleanliness practices during surgery dramatically improved patient outcomes^[1].

These infections are a type of hospital-acquired infection (an infection you get while receiving medical care in a hospital or healthcare facility). Surgical site infections represent the primary source of such infections in surgical patients^[1].

Types of Surgical Site Infections

The Centers for Disease Control and Prevention (CDC) classifies surgical site infections into three main categories based on how deep the infection goes^[2][4]:

Superficial incisional infections affect only the skin and the tissue just beneath it where the surgeon made the cut. These are the most common type, accounting for more than half of all surgical site infections. You might notice pus coming from the surgical site, or the surgeon may identify it as infected^[2].

Deep incisional infections go deeper than the skin, affecting muscles or the connective tissue (tissue that separates your muscles or encloses your organs). An infection after cuts in your breastbone during heart surgery is an example of a deep incisional infection^[2].

Organ or space infections affect organs or the spaces between organs. During surgery, your surgeon may need to gently move an organ aside to reach the surgical area. This can sometimes lead to an infection in that organ or in the space around it^[2].

Any surgical wound that a surgeon declares infected or deliberately opens because of suspected infection is classified as a surgical site infection. These infections must occur within 30 days after surgery, or within one year if a medical device has been implanted during the procedure^[1].

How Common Are These Infections?

The U.S. CDC estimates that 1 to 3 out of every 100 people who have surgery develop a surgical site infection^[2]. While this may seem like a small number, surgical site infections contribute to significant health problems. Current data reveals that they are responsible for over 2 million hospital-acquired infections in the United States each year^[1].

Most surgical wound infections appear within the first 30 days after surgery^[3]. However, infections can sometimes develop several months after an operation^[7].

In low- and middle-income countries, the rates can be higher. About 11% of patients who undergo surgery in these regions develop an infection during the process. In Africa, up to 20% of women who have a caesarean section contract a wound infection, which affects both their health and their ability to care for their babies^[19].

What Causes Postoperative Wound Infections?

Bacteria cause surgical wound infections. While there are millions of different bacteria, certain types are most commonly responsible for postoperative infections^[2]:

Staphylococcus aureus is the most common form of bacteria responsible for infections at surgical sites. About 30% of people have these bacteria living in their noses. In most situations, they are harmless until they get inside your body through a surgical wound^[2].

Streptococcus pyogenes (also called Group A Streptococcus) is the bacterium that causes strep throat. These bacteria live in people’s noses and throats and may spread when people sneeze, cough, or talk^[2].

Enterococci are bacteria that normally live in your intestinal tract. They usually don’t cause disease unless they move from your intestines to parts of your body that aren’t supposed to have bacteria. For example, if enterococci from your large intestine spill into your belly during surgery, you may develop an infection^[2].

Pseudomonas aeruginosa infections may occur if you have these bacteria on your skin or if they are on a medical device, like a urinary catheter or ventilator^[2].

Surgical wounds can become infected in several ways. Germs that are already on your skin can spread to the surgical wound. Germs that are inside your body or from the organ being operated on can cause infection. Bacteria in the environment around you during or after surgery can also lead to infection^[3].

Most surgical wound infections come from the body’s own flora (microorganisms typically found on your skin, mucous membranes, or in hollow organs). Generally, the higher the concentration of these microorganisms, the greater the risk of wound infection. When there are more than 10,000 microorganisms per gram of tissue, the likelihood of a wound infection increases^[6].

Risk Factors for Infection

Anyone who has surgery is at risk for developing an infection, but certain factors increase this risk^[3][4]:

• Being an older person
• Having poorly controlled diabetes
• Having problems with your immune system
• Being overweight or obese
• Being a smoker
• Taking corticosteroids (medicines like prednisone)
• Having surgery that lasts longer than 2 hours
• Having certain types of surgery, such as surgery to treat an existing infection like an abscess
• Being malnourished

Some types of surgery carry more risk of infection than others. This depends on the risks from different types of germs. Infections are more likely to happen after surgery on parts of the body that have lots of bacteria, such as the gut^[7].

Signs and Symptoms

Symptoms typically develop three to seven days after surgery, though they can appear at any time from 2 to 3 days after surgery until the wound has healed, which is usually 2 to 3 weeks after the operation^[2][7]. Your symptoms may vary depending on the type of surgery you had.

General signs of a surgical site infection include^[2][4]:

• Thick, cloudy, white or cream-colored discharge (pus) draining from the wound
• A noticeable odor coming from the surgical site
• An opening in the cut line (the line may get deeper, longer, or wider)
• Redness or color changes in your skin around the wound that go beyond the edge of the cut
• Pain when you touch the wound or the area around it
• The surgical area feels warm or hot to your touch
• Swelling around the surgical site
• Fever (greater than 101 degrees Fahrenheit or 38.4 degrees Celsius)
• Chills
• Feeling generally unwell

You may have an infection if you notice any of these symptoms. The skin around your wound might be red, sore, or feel hot and swollen. Your wound might open up or have liquid coming out of it^[7].

How Infections Are Diagnosed

Diagnosis of a postoperative wound infection primarily relies on clinical evaluation by your healthcare provider. Your doctor will examine your wound and look for the signs of infection described above^[1].

In some cases, additional tests may be necessary. If there is drainage from your wound, your doctor may take a sample with a swab and send it to a laboratory for testing. This helps identify the specific bacteria causing the infection and determines which antibiotic would work best^[3][7].

Some wounds are infected with MRSA (methicillin-resistant Staphylococcus aureus), which is a type of bacteria resistant to commonly used antibiotics. Identifying MRSA requires special testing and needs a specific antibiotic to treat it^[3].

Imaging tests, such as CT scans, may be used if your doctor suspects a deep infection or an abscess (a pocket of pus) in deeper tissues or organs^[1].

Treatment Options

Treatment for postoperative wound infections typically involves antibiotics and, in some cases, additional surgical procedures to clean the wound^[3].

Antibiotic Treatment

Antibiotics are used to treat most wound infections. You may be started on antibiotics through a vein (IV) and then switched to pills later. The length of time you will need to take antibiotics varies but will typically be for at least one week. It is important to take all of your antibiotics and complete the entire course of treatment, even if you feel better^[3].

Surgical Treatment

Sometimes your surgeon needs to perform a procedure to clean the wound. This can be done in the operating room, in your hospital room, or in a clinic. The surgeon will^[3]:

• Open the wound by removing some or all of the staples or sutures (stitches)
• Test the pus or tissue in the wound to identify the infection and determine the best antibiotic
• Debride the wound by removing dead or infected tissue
• Rinse the wound with salt water (saline solution)
• Drain any pocket of pus (abscess) if present
• Pack the wound with saline-soaked dressings and cover it with a bandage

Wound Care

Your surgical wound may need to be cleaned and the dressing changed regularly. You may learn to do this yourself, or nurses may do it for you. If you do this yourself, you will remove the old bandage and packing, clean the wound, and put in new, clean packing material with a new bandage. You can shower to wet the wound, which allows the bandage to come off more easily^[3].

To help some surgical wounds heal, you may have a wound VAC (vacuum-assisted closure) dressing. This is a negative pressure (vacuum) dressing that includes a vacuum pump, a foam piece cut to fit the wound, and a vacuum tube with a clear dressing taped on top. It increases blood flow in the wound and helps with healing. The dressing and foam piece are changed every 2 to 3 days^[3].

It may take days, weeks, or even months for the wound to be clean, clear of infection, and finally heal. If the wound does not close by itself, you may need a skin graft or muscle flap surgery to close it. However, the surgeon will not perform this procedure until after the infection has cleared^[3].

Prevention Strategies

Healthcare providers and hospitals work hard to prevent surgical site infections. There are important steps you can take before, during, and after surgery to reduce your risk^[4].

Before Surgery

• Tell your healthcare provider about other medical problems you may have. Health problems such as allergies, diabetes, and obesity could affect your surgery and your treatment
• Quit smoking. Patients who smoke get more infections
• Do not shave near where you will have surgery. Shaving with a razor can irritate your skin and make it easier to develop an infection
• Follow the preparation instructions you’re given, including using any special soaps or cleansers correctly
• You may be asked to have a shower or bath with soap and water before coming to the hospital^[7]

At the Time of Surgery

• Speak up if someone tries to shave you with a razor in the area where you will have surgery
• Ask why you need to be shaved and talk with your surgeon if you have concerns^[4]

During Your Hospital Stay

• Wash your hands often
• If you do not see your healthcare provider clean their hands, ask them to do so
• Family and friends should not touch the surgical wound or dressings
• Family and friends should clean their hands with soap and water or an alcohol-based hand rub before and after visiting you
• Do not allow others to touch your cut
• Remind healthcare providers to wear gloves or masks if you don’t see them doing so^[4]

At Home After Surgery

• Follow the care instructions you’re given carefully
• Keep the dressings clean and dry
• Wash your hands before cleaning the surgical site or changing dressings
• Keep the wound covered
• Take your medicines and follow medication instructions
• Maintain a healthy diet
• Avoid using tobacco
• Do not put anything on the surgical site, like ointment, unless your provider tells you to^[4]

All hospital staff are taught to keep their hands clean to stop the spread of infection. If you think that a member of staff may have forgotten to wash their hands before touching your dressing, drain, or wound, please remind them^[7].

Recovery and Outlook

If the wound infection is not very deep and the opening in the wound is small, you will be able to take care of yourself at home. Most patients with wound infections are managed in the community with dressing changes to optimize healing, which usually occurs by secondary intention (healing from the bottom of the wound up, rather than closing the edges together)^[3][11].

Surgical site infections contribute significantly to increased hospital stays and healthcare costs. The increased hospital stay due to surgical site infection has been estimated at 7 to 10 days, increasing hospitalization costs by 20%^[11].

In the United States, surgical site infections contribute to patients spending more than 400,000 extra days in hospital at a cost of an additional $900 million per year^[19].

With proper treatment and care, most surgical wound infections can be successfully treated. Treatment generally includes antibiotics, but recovery depends on the type and severity of infection. It is important to treat any infection as soon as possible to stop it from getting worse^[4][7].

When to Contact Your Healthcare Provider

If you have any symptoms of an infection, contact the hospital or your healthcare provider straight away. It is important to treat any infection as soon as possible to prevent complications^[4][7].

Contact your care team immediately if you notice^[3][7]:

• Pus or drainage from the surgical site
• A bad smell coming from the wound
• Fever or chills
• The surgical site is hot to touch
• Increased redness around the surgical site
• Pain or soreness when you touch the wound
• The wound opens up
• You feel generally unwell

You should also contact your healthcare provider if you’re having trouble during your recovery or develop other complications, such as nausea or vomiting that doesn’t get better, pain that doesn’t improve with medication, cough or chest pain, difficulty breathing, or pain or swelling in your feet or legs^[15].

Make sure you understand how to care for your wound before you leave the hospital. Know who to contact if you have questions or problems. Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments^[16].