Summary

Surgical site infection (SSI) is an infection that occurs at or near a surgical incision within 30 days of surgery (or 90 days if an implant was used). Think of a surgical wound as a break in your skin's protective barrier—when bacteria get into the wound, they can cause infection, leading to redness, swelling, pain, and discharge. SSIs are common complications, occurring in 2-5% of surgeries, and can range from superficial (skin only) to deep (fascia, muscle, organ space). The most common causes are bacteria from the patient's own skin, from the surgical environment, or from contaminated instruments. The key to management is recognizing the infection (redness, swelling, pain, discharge, fever), classifying the severity (superficial vs deep), providing appropriate antibiotics (targeted based on culture), and surgical drainage if needed (abscess, deep infection). Most superficial SSIs respond well to antibiotics, but deep infections may need surgical drainage or debridement.

Key Facts

• Definition: Infection at or near surgical incision within 30 days (or 90 days if implant)
• Incidence: Common (2-5% of surgeries)
• Mortality: Low (<1%) unless complications (sepsis, deep infection)
• Peak age: All ages, but more common in older adults
• Critical feature: Redness, swelling, pain, discharge, fever
• Key investigation: Clinical diagnosis (usually), wound swab, blood cultures if systemic
• First-line treatment: Antibiotics, drainage if abscess

Clinical Pearls

"Redness + swelling + discharge = infection" — The classic triad of SSI is redness, swelling, and discharge (pus). If you see these, it's an infection.

"Superficial vs deep matters" — Superficial SSIs (skin only) can often be managed with antibiotics. Deep SSIs (fascia, organ space) usually need surgical drainage.

"Culture before antibiotics" — Always take a wound swab before starting antibiotics (if possible). This helps target treatment.

"Prevention is key" — Most SSIs are preventable with proper technique, antibiotics, and sterile conditions. Prevention is better than treatment.

Why This Matters Clinically

SSIs are common complications that can prolong recovery, increase costs, and rarely cause serious complications (sepsis, deep infection). Early recognition, appropriate antibiotics, and surgical drainage if needed are essential. This is a condition that surgeons manage frequently, and prompt treatment prevents complications.

Structured Approach: ABCDE

A - Airway

• Assessment: Usually patent
• Action: Secure if compromised

B - Breathing

• Look: Usually normal
• Listen: Usually normal
• Measure: SpO2 (usually normal)
• Action: Support if needed

C - Circulation

• Look: Usually normal (may have signs of sepsis)
• Feel: Pulse (usually normal), BP (usually normal)
• Listen: Heart sounds (usually normal)
• Measure: BP (usually normal), HR
• Action: Monitor if sepsis

D - Disability

• Assessment: Usually normal (may be altered if sepsis)
• Action: Assess if severe

E - Exposure

• Look: Wound examination
• Feel: Tenderness, warmth, assess depth
• Action: Complete examination

Specific Examination Findings

Wound Examination:

• Inspection:
  • Redness: Extent of redness
  • Swelling: Extent of swelling
  • Discharge: Type, amount
  • Separation: Wound opens?
• Palpation:
  • Tenderness: Painful
  • Warmth: Warm to touch
  • Fluctuance: Abscess (if present)
  • Depth: Assess depth

Assess for Deep Infection:

• Extent: How far does redness extend?
• Tense: Is swelling tense?
• Systemic: Fever, unwell?

Special Tests

Natural History (Without Treatment)

Untreated SSI:

• Spread: May spread deeper
• Sepsis: Risk of sepsis
• Poor outcomes: If not treated

Outcomes with Treatment

Factors Affecting Outcomes:

Good Prognosis:

• Early treatment: Better outcomes
• Superficial: Usually recovers quickly
• No complications: Better outcomes
• Good nutrition: Better healing

Poor Prognosis:

• Delayed treatment: May spread deeper
• Deep infection: Longer recovery
• Sepsis: Worse outcomes
• Poor nutrition: Poor healing

Prognostic Factors

Key Guidelines

1. NICE Guidelines (2019) — Surgical site infections: prevention and treatment. National Institute for Health and Care Excellence

Key Recommendations:

• Prevention is key
• Early recognition
• Appropriate antibiotics
• Surgical drainage if deep
• Evidence Level: 1A

Landmark Trials

Multiple studies on prevention, antibiotic treatment, outcomes.

Evidence Strength

What is a Surgical Site Infection?

A surgical site infection (SSI) is an infection that occurs at or near your surgical incision. Think of a surgical wound as a break in your skin's protective barrier—when bacteria get into the wound, they can cause infection, leading to redness, swelling, pain, and discharge.

In simple terms: Your surgical wound has become infected. This is common and usually easily treated, but it needs prompt treatment to prevent complications.

Why does it matter?

SSIs are common complications that can prolong recovery and rarely cause serious complications. Early recognition and appropriate treatment are essential. The good news? Most SSIs respond well to treatment.

Think of it like this: It's like your surgical wound getting infected—it needs treatment, but most infections are easily treated.

How is it treated?

1. Assessment:

• Examination: Your doctor will examine the wound to see how serious the infection is
• Swab: Your doctor may take a swab to identify the bacteria
• Why: To see how serious it is and plan treatment

2. Antibiotics:

• What: You'll get antibiotics to fight the infection
• How: Usually by mouth (if superficial) or through a drip (if deeper or more serious)
• Duration: Usually 7-14 days
• Why: To kill the bacteria causing the infection

3. Wound Care:

• Dressings: You'll need regular wound care and dressings
• Why: To keep the wound clean and help it heal

4. Drainage (If Needed):

• If abscess: The pus will be drained (surgically or with a needle)
• If deep infection: You may need surgery to drain the infection
• Why: To remove pus and help the infection clear

The goal: Fight the infection (antibiotics, drainage if needed) and help the wound heal.

What to expect

Recovery:

• Superficial infections: Usually start improving within days with antibiotics
• Deep infections: May take longer, may need drainage
• Full recovery: Most people recover completely

After Treatment:

• Antibiotics: You'll continue antibiotics until the infection is cleared
• Wound care: You'll need regular wound care
• Monitoring: Your doctor will monitor to make sure you're improving
• Follow-up: Regular follow-up to monitor healing

Recovery Time:

• Superficial: Usually days to weeks
• Deep: Usually weeks

When to seek help

See your doctor if:

• Your surgical wound is red, swollen, or painful
• Your surgical wound has discharge (pus or fluid)
• Your surgical wound has a fever
• You have concerns about your surgical wound

Call 999 (or your emergency number) immediately if:

• You have a surgical wound infection and feel very unwell
• You have a surgical wound infection and have a high fever
• You have a surgical wound infection and the redness is spreading rapidly
• You feel very unwell

Remember: If your surgical wound is red, swollen, painful, or has discharge, especially if you have a fever, see your doctor. SSIs are common and usually easily treated, but they need prompt treatment to prevent complications. Don't delay—if you're worried, seek help.