Table I.

Health Protection Agency definition of superficial and deep surgical site infection

Incisional infection
Superficial incisional infection*
SSI that occurs within 30 days of surgery, involves only the skin or subcutaneous tissue of the incision, and meets at least one of the following criteria:
1. Purulent drainage from superficial incision
2. Culture of organisms and pus cells present in fluid/tissue from superficial incision wound swab from superficial incision
3. At least two symptoms of inflammation: a) pain, b) tenderness, c) localized swelling, d) redness, e) heat, and either: f) incision deliberately opened to manage infection, or g) clinician’s diagnosis of superficial SSI
Deep incisional infection
SSI involving the deep tissues (i.e. fascial and muscle layers), within 30 days of surgery (or one year if an implant is in place), and the infection appears to be related to the surgical procedure and meets at least one of the following criteria:
1. Purulent drainage from deep incision (not organ space)
2. Organisms from culture and pus cells present in fluid/tissue from deep incision or wound swab from deep incision
3. Deep incision dehisces or deliberately opened and patient has at least one symptom of fever or localized pain/tenderness
4. Abscess or other evidence of infection in deep incision: reoperation, histopathology, or radiology
5. Clinician’s diagnosis of deep incisional SSI

^*Stitch abscesses (minimal inflammation/discharge at suture point) do not classify as deep surgical site infection (SSI)