The Short Answer: Multiple randomised controlled trials have found no statistically significant difference in surgical site infection rates between masked and unmasked surgical teams. The evidence challenges a deeply held assumption.

Surgical masks have been standard in operating rooms for over a century. They are so ubiquitous that questioning them feels almost heretical. But the evidence for their role in preventing surgical site infections is far weaker than most clinicians realise.

What the Cochrane Review Found

A Cochrane systematic review, the gold standard of evidence synthesis, analysed three randomised controlled trials covering 2,106 patients (Vincent & Edwards, 2016). The question was straightforward: do surgical face masks worn by the operating team reduce wound infection rates?

The answer: no statistically significant difference between masked and unmasked surgical teams.

An earlier study by Tunevall (1991) tracked 3,088 patients across alternating masked and unmasked operating weeks. Surgical site infections were 4.7% with masks and 3.5% without. The difference was not statistically significant, and if anything the unmasked weeks fared slightly better.

So What Are Masks Actually For?

This is not an argument against wearing masks. Masks clearly protect the wearer from blood splashes and bodily fluid exposure. That function is well established, undisputed, and important.

But the evidence for masks protecting patients from airborne bacterial contamination originating from the surgical team is surprisingly thin. The assumption has been repeated so often it is treated as established fact, even though the randomised evidence does not support it.

Why This Matters Beyond Masks

The mask question illustrates a broader principle in perioperative practice. Many OR clothing rules are rooted in tradition rather than rigorous evidence. When we assume something works simply because it has always been done, we risk two things. First, we may be enforcing practices that do not help. Second, and perhaps more importantly, we may be overlooking interventions that actually would.

The same evidence-based scrutiny should apply to every piece of surgical attire. Choosing a scrub cap based on proven fabric performance, particle filtration, weave density, fit, rather than habit or institutional inertia is exactly this kind of thinking. The question should never be "has it always been done this way?" but "does the evidence support this?"

The Cochrane review does not say masks are useless. It says we have not proven they prevent surgical site infections. That distinction matters enormously. It should prompt us to be more rigorous about questioning every assumption we carry into theatre, and more willing to invest in the interventions where the evidence actually is strong.