ConditionInfections
Postoperative Infection
A postoperative infection is any infection that develops after surgery. The most common is a surgical site infection of the incision or the tissues beneath it, but pneumonia, urinary tract infections, bloodstream infections from IV lines and C. difficile diarrhea also occur. Signs include increasing redness, swelling, pain, warmth or pus at the wound, fever, and feeling unwell, usually 3 to 10 days after surgery. Most are treated successfully with wound care and antibiotics, but sepsis is a medical emergency.
Also called: Surgical site infection (SSI), wound infection after surgery, post-surgical infection, infected incision
At a glance
- Most common
- Surgical site infection, in about 1 to 3% of operations (higher for bowel surgery).
- Other types
- Pneumonia, urinary tract infection, line infections, C. difficile, infected implants.
- Typical timing
- Wound infections usually appear 3 to 10 days after surgery; implant infections can occur up to a year later.
- Warning signs
- Spreading redness, warmth, swelling, pus, opening wound, fever, chills.
- Treatment
- Opening and draining the wound, antibiotics, sometimes further surgery.
When to get help
Call 911 or go to the ER
- Fever with confusion, fast breathing, fast heartbeat, very low urine, or cold, clammy or mottled skin (possible sepsis). Call 911 or your local emergency number
- Rapidly spreading redness, severe pain out of proportion to the wound, dark or blistered skin, or crackling under the skin (possible necrotizing infection)
- A wound that splits open with tissue or organs visible
See a doctor within a day or two
- Fever of 38.3 °C (101 °F) or higher after surgery
- Redness spreading more than about 1 to 2 cm (half an inch) from the incision, increasing pain, warmth or swelling
- Pus or cloudy, foul-smelling drainage from the wound
- Cough with fever and breathlessness, burning urination, or watery diarrhea 3 or more times a day after surgery
Book a routine appointment
- Mild redness along the incision edges that is not spreading
- Clear or slightly pink drainage in the first days
- Questions about wound care: contact your surgical team
Types of postoperative infection
| Infection | Where | Typical signs |
|---|---|---|
| Superficial incisional SSI | Skin and fat at the incision | Redness, warmth, tenderness, pus |
| Deep incisional SSI | Muscle and fascia | Pain, fever, wound separation |
| Organ or space SSI | Abdomen, joint, chest or other operated space | Abscess, fever, worsening pain |
| Pneumonia | Lungs | Cough, fever, breathlessness |
| Urinary tract infection | Bladder, often after a catheter | Burning, frequency, fever |
| Line infection | IV or central line site | Redness at the line, fever |
| C. difficile infection | Colon, after antibiotics | Watery diarrhea, cramps, fever |
| Prosthetic or implant infection | Joints, mesh, heart valves | Pain, swelling, fever; may appear months later |
Causes and risk factors
Bacteria from the patient's own skin or gut cause most surgical site infections, mainly Staphylococcus aureus (including MRSA), streptococci and gut bacteria.
Patient factors
- diabetes and high blood sugar around surgery
- smoking
- obesity
- older age
- poor nutrition
- weakened immune system, steroids or chemotherapy
- infection elsewhere in the body
- MRSA carriage
Surgical factors
- surgery on the bowel or in contaminated areas
- emergency surgery
- long operations
- implants
- blood loss and low body temperature during surgery
Symptoms
Wound infection:
- increasing pain after it had been improving
- redness spreading out from the incision
- warmth and swelling
- pus or cloudy, smelly drainage
- the wound opening up
- fever and chills
Normal healing can include mild redness along the edges, mild swelling and small amounts of clear or pink fluid in the first few days. These should steadily improve.
Diagnosis
- examination of the wound
- swab or sample of pus for culture
- blood tests: white cell count, CRP, blood cultures if fever is high
- ultrasound or CT scan for deep abscesses
- chest X-ray, urine tests or stool tests for other infections
Treatment
- Opening and draining the wound: often the most important step for superficial infections. The wound is then cleaned and packed, or managed with a negative pressure (vacuum) dressing.
- Antibiotics: for spreading redness (cellulitis), deep infections or systemic signs; chosen according to cultures and local resistance patterns.
- Drainage of abscesses with a needle under imaging guidance or by surgery.
- Further surgery to remove infected tissue, mesh or implants when needed.
- Supportive care in hospital for sepsis.
Prevention
What hospitals do
- antibiotics within an hour before the incision, for appropriate operations
- hair clipping rather than shaving
- skin antiseptic preparation
- keeping body temperature normal and blood sugar controlled
- sterile technique and timely removal of catheters and lines
What you can do
- stop smoking at least 4 weeks before surgery
- control blood sugar if you have diabetes
- shower with antiseptic soap before surgery if advised
- do not shave the surgical area yourself
- wash hands before touching the wound, and ask visitors and staff to do the same
- follow wound care instructions, and keep the dressing clean and dry
- walk early and do breathing exercises to prevent pneumonia
- report warning signs early
Frequently asked questions
What are the signs of infection after surgery?
Watch for increasing redness, warmth and swelling around the incision, worsening pain, pus or foul-smelling drainage, the wound opening, and fever or chills. Infections usually appear 3 to 10 days after surgery. Contact your surgical team promptly if these develop.
Is a fever after surgery normal?
A low fever in the first day or two after major surgery is common and often due to inflammation. A fever of 38.3 °C (101 °F) or higher, a fever after the first few days, or fever with wound changes, cough, urinary symptoms or diarrhea should be checked.
How are surgical wound infections treated?
Superficial infections are usually treated by opening the wound to drain pus, with regular dressing changes. Antibiotics are added for spreading redness or deeper infections. Abscesses may need drainage, and infected implants sometimes need further surgery.
How can I prevent infection after surgery?
Stop smoking before surgery, control blood sugar, keep the wound clean and dry, wash your hands before touching it, follow your surgeon's instructions, move around early, and report any warning signs quickly.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Surgical site infection (SSI) event and patient FAQs
- American College of Surgeons and Surgical Infection Society: Surgical site infection guidelines
- World Health Organization: Global guidelines for the prevention of surgical site infection
- Agency for Healthcare Research and Quality: Preventing hospital-acquired infections
- MedlinePlus: Surgical wound infection