Surgical Site Infection

A surgical site infection is an infection that occurs in the wound created by an invasive surgical procedure.

Despite the necessary precautions taken (such as aseptic technique, prophylactic antibiotics, laminar air flow), there is always the risk of infection in or around the area that has been instrumented in surgery.

In this article, we shall look at the risk factors, clinical features and management of surgical site infections.

Risk Factors

There are several factors that increase the risk of a surgical site infection, as shown in Table 1 (as based on the SIGN guidelines)

Patient Factors Operation Factors
Extremes of age

Poor nutritional state

Diabetes mellitus or renal failure


Co-existing infection at other site


Long post-operative stay

Preoperative shaving

Length of operation

Foreign material in surgical site

Insertion of surgical drain

Inadequate instrument sterilisation

Poor closure of wound

Post-operative hypothermia

Table 1 – Risk Factors for Surgical Site Infections


Clinical Features

The symptoms of a surgical site infection typically appear 2-7 days’ post-procedure. However, infections with any prosthetic insertion can present later, due to bacterial spread from another location.

The common clinical features of surgical site infections include:

  • Erythema
  • Localised pain – this is often different to the typical post-operative pain.
  • Pus/discharge from the wound
  • Wound dehiscence
  • Unexplained persistent pyrexia
Fig 1 - (A) Purulent discharging forming in open wound; (B) Erythema and pus seen in closed wound; (C) drain placed in situ to remove any potentially accumulating pus.

Fig 1 – (A) Purulent discharging forming in open wound; (B) Erythema and pus seen in closed wound; (C) drain placed in situ to remove any potentially accumulating pus.


Any suspected surgical site infection should have swabs taken for culture at the wound site. Perform blood tests for infection markers (FBC, CRP), and take blood cultures if pyrexial.


The management of a surgical site infection follows four main principles:

  • Removal of sutures/clips – this may seem counterintuitive to open the wound, however this allows for the drainage of pus and the opportunity for the wound to be packed if required.
  • Discharge or drainage of pus
  • Empirical antibiotic prescription – Different wounds are often caused by different organisms (e.g. laparotomy wound infection is more likely to be caused by an E. Coli organism). Seek microbiological assistance as required and follow local hospital antibiotic guidelines.
  • Monitor closely for signs of sepsis and treat accordingly.


The prevention of surgical site infections can be achieved in the pre-operative, intraoperative and post-operative settings.

Pre-Operative Phase

  • Give prophylactic antibiotics if indicated (clean surgery involving a prosthesis, clean-contaminated surgery, or contaminated surgery).
  • Do not remove hair routinely; if necessary do this immediately prior to surgery (i.e. when anaesthetised). The use of razors to remove hair actually increases the risk of SSI.

Intraoperative Phase

  • Prepare the skin at the surgical site immediately before the incision using an antiseptic preparation (povidoneiodine or chlorhexidine are most suitable)
    • A multi-centre study showed that wound edge protectors do not appear to provide any additional benefit
  • Change gloves or gowns if you become contaminated
  • Wear appropriate hair nets and face masks
  • Use an appropriate interactive dressing at the end of the operation to cover all surgical incisions

Post-Operative Phase

  • Monitor wounds closely. The use of see-through dressings will limit the number of dressing changes, thus minimise the chance for bacterial contamination.
  • Ensure that wounds in difficult areas such as skin creases and underneath skin folds (such as groin) are closely observed. Patients may require pads to separate the wound from overlying skin or be bed bound to remove pressure on a wound.
  • Refer to a tissue viability nurse for advice on appropriate dressings for the management of surgical wounds that are healing by secondary intention.

Note: Interestingly, whilst wounds are dressed as routine post-surgical care, recent work has identified that there is no difference in the rates of surgical-site infection between wounds covered with different dressings and those left uncovered – nor differences noted in pain, scar or acceptability between dressings.


Question 1 / 5
Which of the following is not a risk factor for a Surgical site infection?


Question 2 / 5
When do SSIs most commonly present


Question 3 / 5
How should a SSI be managed initially?


Question 4 / 5
What is the most likely causative organism of an SSI?


Question 5 / 5
Which of the following does not hep prevent SSIs?


Further Reading

Systemic review and meta-analysis of randomized clinical trials comparing primary vs delayed primary skin closure in contaminated and dirty abdominal incisions
Bhangu A et al., JAMA Surgery

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