Skin grafting the contaminated wound bed: reassessing the role of the preoperative swab

Objective: To investigate use of the preoperative wound swab to predict graft failure compared with establishing the indication for skin grafting on clinical grounds alone.

Method: Patients requiring meshed split-thickness skin grafting were prospectively included; the indication for grafting was established on clinical grounds exclusively. A preoperative swab of the wound bed was taken, but its result was concealed to prevent it influencing clinical decision-making. Negative pressure wound therapy (NPWT) was used for both wound bed preparation and graft fixation. After 2 months, graft area take percentage was measured using digital image processing software and the results validated against the result of the preoperative wound swab.

Results: Eighty-seven wounds were included in the study. Mean graft area take percentage was 88%, with five grafts considered complete failures (<25% take). A posteriori analysis of the wound cultures showed that 53% had been contaminated on grafting, but these did not fare any worse than near-sterile wounds. Qualitative analysis of cultures showed that wounds containing either Pseudomonas aeruginosa or Staphylococcus aureus did have inferior outcome (mean take percentage 78.9% vs 91.3%; p=0.038). Diabetes was also a deteriorating factor (mean take percentage 83.0% vs 90.7%; p=0.004).

Conclusion: Establishing the indication for skin grafting on clinical grounds exclusively does not yield grossly inferior results. In light of recent advances in skin grafting, including use of NPWT as adjuvant therapy, the requirement for routine preoperative wound swabs may be questioned.

Declaration of interest: There were no external sources of funding for this study. The authors have no conflicts of interest to declare.