Surgical Site Infection in Microvascular Free Flap Reconstruction of the Head and Neck: An Analysis of Risk Factors

BACKGROUNDS: Free flap reconstruction has become the standard of care in the repair of complex defects of the head and neck; however, surgical site infection remains a key area for improvement. This study aims to better understand the risk factors for surgical site infection in head and neck free flap reconstruction and gain insight into antibiotic prophylaxis choices. METHODS: This retrospective cohort study reviews data from 100 cases across a 5-year period. Univariate and multivariate analyses have been employed to elucidate statistically significant associations, examining surgical site infection, potential risk factors and other post-operative markers. RESULTS: A surgical site infection developed in 32.0% of cases, with an average onset of 11.3 days post-operation. Preoperative anaemia (OR: 3.259) and a prophylactic antibiotic duration of ≤ 24 h (OR: 3.010) were found to be independently significant risk factors for infection. Furthermore, surgical site infection was found to significantly increase unplanned returns to theatre (p ≤ 0.001), complete flap failure (p = 0.005) and length of stay (p = 0.026). The results also suggest that a 48-h prophylaxis duration may be optimal, with no significant difference in infection rate at this cut-off point. CONCLUSION: To the author's knowledge, this is the first paper to establish preoperative anaemia as an independently significant risk factor for surgical site infection in head and neck free flap operations. This study also finds the Australian guidelines' recommendation of ≤ 24 h of antibiotic prophylaxis to be potentially inadequate in effectively controlling surgical site infection following head and neck free flap reconstruction.