17.1 Surgical Wounds, Surgical Site Infection & Dehiscence
Key Takeaways
- The CDC classifies surgical wounds as class I clean, class II clean-contaminated, class III contaminated, and class IV dirty-infected, and NHSN defines surgical site infection as superficial incisional, deep incisional, or organ/space infection within 30 or 90 days depending on the procedure.
- Evidence-based SSI prevention includes treating remote infections, clipping rather than shaving hair, alcohol-based skin antisepsis (chlorhexidine-alcohol reduced SSI compared with povidone-iodine in a 2010 trial), prophylactic antibiotics timed before incision and not continued after closure in clean and clean-contaminated cases, glucose below 200 mg/dL, and normothermia.
- Fascial dehiscence usually occurs around postoperative days 5 to 8 and is often heralded by a sudden gush of serosanguineous ("salmon-colored") fluid; evisceration is a surgical emergency managed with a sterile saline-moistened dressing and return to the operating room.
- Enterocutaneous fistula output is low under 200 mL/day, moderate 200 to 500 mL/day, and high over 500 mL/day; management follows sepsis control, nutrition, defining the anatomy, and planned procedure, and the FRIENDS factors predict failure of spontaneous closure.
- Closed-incision NPWT is suggested by the World Health Organization for high-risk primarily closed surgical incisions, and surgical wounds that must heal by secondary intention need the same wound bed preparation principles as chronic wounds.
17.1 Surgical Wounds, Surgical Site Infection & Dehiscence
Core Clinical Principle: Most surgical wounds heal quickly, but those that become infected, separate, or form fistulas turn into complex wounds that cost patients months. Wound specialists should know how surgical site infections are defined and prevented, how to recognize dehiscence early, and how to manage open surgical wounds and fistulas.
The CWSP outline lists surgical and surgical procedure wounds under Etiological Considerations. Closure techniques, grafts, and flaps are covered with surgical closure.
Surgical Wound Classification (CDC)
| Class | Definition | Examples |
|---|---|---|
| I – Clean | Uninfected, no inflammation; respiratory, alimentary, genital, and urinary tracts not entered | Hernia repair, thyroidectomy |
| II – Clean-contaminated | Controlled entry into those tracts without unusual contamination | Elective cholecystectomy, colectomy with bowel preparation |
| III – Contaminated | Open fresh accidental wounds, major breaks in sterile technique, gross spillage from the gastrointestinal tract | Penetrating trauma under 4 hours, bowel spillage |
| IV – Dirty-infected | Old traumatic wounds with devitalized tissue, existing infection, or perforated viscera | Perforated diverticulitis with abscess |
Surgical Site Infection Definitions (CDC NHSN)
| Type | Tissue Involved | Time Window |
|---|---|---|
| Superficial incisional | Skin and subcutaneous tissue of the incision | Within 30 days |
| Deep incisional | Fascia and muscle | Within 30 or 90 days, depending on the procedure category |
| Organ/space | Any part of the body deeper than the fascia opened or manipulated during surgery (for example, intra-abdominal abscess) | Within 30 or 90 days, depending on the procedure category |
Signs include pain, tenderness, localized swelling, erythema, warmth, purulent drainage, and deliberate opening of the incision by the surgeon with a positive culture or clinical diagnosis. Stitch abscesses alone do not count as SSI.
Risk Factors and Prevention
| Patient Factors | Procedure Factors |
|---|---|
| Diabetes and perioperative hyperglycemia, obesity, smoking, malnutrition, immunosuppression, Staphylococcus aureus colonization, remote infection, advanced age, radiation | Long operations, contamination class, hypothermia, blood transfusion, poor hemostasis, dead space, excessive tissue trauma, emergency surgery |
Evidence-based prevention measures (drawn from CDC 2017 and WHO guidelines):
- Treat remote infections before elective surgery and encourage smoking cessation.
- Remove hair only when needed, with clippers, not razors.
- Alcohol-based skin antisepsis; in a 2010 randomized trial (Darouiche and colleagues), chlorhexidine-alcohol lowered SSI after clean-contaminated surgery to 9.5% compared with 16.1% with povidone-iodine.
- Prophylactic antibiotics given within 60 minutes before incision (120 minutes for vancomycin and fluoroquinolones), redosed for long procedures, and not continued after closure for clean and clean-contaminated operations.
- Perioperative glucose below 200 mg/dL in all patients, with or without diabetes.
- Normothermia and adequate oxygenation.
- S. aureus decolonization (such as nasal mupirocin with chlorhexidine bathing) for carriers undergoing cardiac and orthopedic surgery.
- Closed-incision NPWT: WHO guidelines suggest prophylactic NPWT on primarily closed incisions in high-risk procedures, considering resources.
Managing SSI and Other Early Complications
- Superficial SSI: Open the incision, drain, cleanse, and pack or dress; antibiotics are added for cellulitis or systemic signs.
- Deep and organ/space SSI: Imaging, drainage (often percutaneous or operative), and targeted antibiotics.
- Seroma: Serous fluid collection; small collections resolve, larger ones need aspiration or drains.
- Hematoma: Raises infection and flap loss risk; evacuate expanding or large collections and review anticoagulation.
- Necrotizing infection: Pain out of proportion, rapidly spreading erythema, or crepitus near an incision needs emergency surgical exploration.
Dehiscence and Evisceration
- Superficial dehiscence separates skin and subcutaneous tissue and is managed as an open wound, often with moist dressings or NPWT.
- Fascial dehiscence most often occurs around postoperative days 5 to 8. A sudden gush of serosanguineous ("salmon-colored") fluid from an abdominal incision is a warning sign.
- Evisceration (bowel protruding through the wound) is a surgical emergency: keep the patient supine with knees flexed, cover the viscera with sterile saline-moistened dressings, keep NPO, and return to the operating room.
- Risk factors: Infection, obesity, malnutrition, corticosteroids, chronic cough, ascites, emergency surgery, and poor closure technique.
Special Surgical Wounds
- Sternal wounds: Deep sternal wound infection and mediastinitis are serious; bilateral internal mammary artery harvest in patients with diabetes and obesity increases risk. Treatment combines debridement, NPWT as a bridge, antibiotics, and muscle flap closure.
- Open abdomen: Temporary abdominal closure with NPWT systems protects viscera while swelling resolves.
- Pilonidal and perineal wounds: Heal slowly by secondary intention; off-midline closure techniques and NPWT may help.
- Surgical wounds healing by secondary intention: Apply the same principles as chronic wounds (debridement, moisture balance, infection control, nutrition).
Enterocutaneous Fistulas
| Output | Classification |
|---|---|
| Under 200 mL/day | Low output |
| 200 to 500 mL/day | Moderate output |
| Over 500 mL/day | High output |
Management (SNAP): Sepsis control and skin protection, Nutrition (often parenteral for high output) and fluid and electrolyte replacement, Anatomy defined with imaging, and Planned procedure, usually delayed several months if the fistula does not close. Protect skin with pouching systems, wound managers, and barrier products; NPWT can be used with fistula isolation devices in selected wounds.
FRIENDS factors that prevent spontaneous closure: Foreign body, Radiation, Inflammatory bowel disease or infection, Epithelialization of the tract, Neoplasm, Distal obstruction, and Steroids (some versions use short tract length instead).
Clinical Traps
Trap 1: Treating a Salmon-Colored Gush With a Dressing Change
Serosanguineous drainage from an abdominal incision around day 5 to 8 is fascial dehiscence until proven otherwise. Examine the fascia and involve the surgeon immediately.
Trap 2: Continuing Prophylactic Antibiotics for Days
Extending prophylaxis after closure of a clean or clean-contaminated operation does not lower SSI and promotes resistance and C. difficile infection.
Twelve days after an open colectomy, a patient has purulent drainage from the midline incision. CT shows an abscess in the subcutaneous fat that extends through a defect in the fascia and muscle layers, but no intra-abdominal collection. Under CDC NHSN definitions, how is this surgical site infection classified?
On postoperative day 6 after an emergency laparotomy, a patient with obesity and chronic obstructive pulmonary disease coughs and notices a sudden gush of pink, salmon-colored fluid soaking the dressing. The skin staples are intact. What is the most appropriate response?
A patient has an enterocutaneous fistula producing 750 mL/day after bowel surgery for Crohn disease. Imaging shows a short, epithelialized tract and a distal bowel stricture. Which statement is most accurate?